Poly(1-butyl-3-vinylimidazolium bromide)is a polymerized ionic liquid(PILs),a relatively new class of materials that combines the attractive properties of ionic liquids(ILs)and polyelectrolytes and finds wide applicat...Poly(1-butyl-3-vinylimidazolium bromide)is a polymerized ionic liquid(PILs),a relatively new class of materials that combines the attractive properties of ionic liquids(ILs)and polyelectrolytes and finds wide applications.The backbone of this PIL is composed of quaternary imidazolium salts,which are among the most promising and popular ILs.However,little is known about the physicochemical characteristics of the aqueous solutions of this PIL.In this study,we synthesized and characterized samples of this PIL and obtained experimental data on the viscosity,static and dynamic light scattering,and nuclear magnetic resonance diffusometry for aqueous and aqueous KBr solutions with varying polymer contents at T=298.15 K.We discuss the effects of the polymer concentration and salinity on the behavior of the solution.展开更多
The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of po...The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.展开更多
A novel Ni（Ⅱ） ion-imprinted silica gel polymer was prepared via the surface imprinting technique combined with aqueous solution polymerization by using 2-acrylamido-2-methyl-1-propanesulfonic acid（AMPS） as a func...A novel Ni（Ⅱ） ion-imprinted silica gel polymer was prepared via the surface imprinting technique combined with aqueous solution polymerization by using 2-acrylamido-2-methyl-1-propanesulfonic acid（AMPS） as a functional monomer for the selective separation of Ni（Ⅱ） from aqueous solution. The sorbent showed good chemical and thermal stability. Kinetics studies indicated that the equilibrium adsorption was achieved within 10 min and the adsorption kinetics fitted well with the pseudo-second-order kinetic model. The maximum adsorption capacity of the ion-imprinted polymer towards Ni（Ⅱ） at the optimal p H of 7.0 was 66.22 mg·g^（-1）. The relative selectivity coefficients of the sorbent were 9.23, 15.71, 14.72 and 20.15 for Ni（Ⅱ）/Co（Ⅱ）, Ni（Ⅱ）/Cu（Ⅱ）, Ni（Ⅱ）/Zn（Ⅱ） and Ni（Ⅱ）/Pb（Ⅱ）, respectively. The adsorption isotherm fitted well with Langmuir isotherm model. The thermodynamic results indicated that the adsorption of Ni（Ⅱ） was a spontaneous and endothermic process. The sorbent showed good reusability evidenced by six cycles of adsorption/desorption experiments. The precision of this method is satisfactory. Thus, the prepared sorbent can be considered as a promising sorbent for selective separation of Ni（Ⅱ） in real water samples.展开更多
A series of low-temperature phase transitions of sodium aluminate solutions were studied by differential scanning calorimetry (DSC) and Raman spectroscopy. The results indicate that NaOH concentration is a primary imp...A series of low-temperature phase transitions of sodium aluminate solutions were studied by differential scanning calorimetry (DSC) and Raman spectroscopy. The results indicate that NaOH concentration is a primary impact factor for the binary eutectic point and ice melting temperature of sodium aluminate solutions with low NaOH concentration. In addition, the phase transition process of sodium aluminate solutions with low NaOH concentration from 123.15 to 283.15 K is divided into four steps: non-crystal to crystal, ternary eutectic reaction, binary eutectic reaction and ice melt. The projection phase diagram of NaOH-Al(OH)3-H2O system at low temperature was plotted, in which the ternary eutectic temperature for sodium aluminate solutions is 183.15 K.展开更多
Behenyl acrylate is a kind of highly efficient pour point depressants. In order to promote theapplication of the pour pint depressant in transportation of crude oils, polybehenyl acrylate was synthesizedby solution po...Behenyl acrylate is a kind of highly efficient pour point depressants. In order to promote theapplication of the pour pint depressant in transportation of crude oils, polybehenyl acrylate was synthesizedby solution polymerization. These conclusions can be drawn from the experimental results that the sequenceof chain transfer constants of four solvents is arranged in the following decreasing order: carbon tetrachloride(6.010-5)>chloroform (2.810-5)>methylbenzene (2.510-5)>tetrachloroethane (1.610-5). The average molecu-lar weight of polybehenyl acrylate mainly depends on the chain transfer constant of the solvents. However, ifthe monomer conversion was higher than 35%, an abnormal phenomenon occurred, resulting in higher aver-age molecular weight of polybehenyl acrylate obtained in methylbenzene solution compared to that obtainedin tetrachloroethane solution. It was attributed to the influence of gelation on the average molecular weight ofpolybehenyl acrylate, which was stronger than the impact of chain transfer in methylbenzene.展开更多
The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions am...The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions among polymer monomers are focused. Extensive simulations show that the dependence of diffusion coefficient D on the polymer concentration c agrees with Phillies equation D-exp （-αc^δ） with a scaling exponent δ≈0.97 which coincides with the experimental one in literature. For increasing nanoparticle size, the scaling prefactor α increases monotonically while the scaling exponent always keeps fixed. Moreover, we also study the diffusion of nanoparticle without hydrodynamic interactions and find that mobility of the nanoparticle slows down, and the scaling exponent is obviously different from the one in experiments, implying that hydrodynamic interactions play a crucial role in the diffusion of a nanoparticle in semidilute polymer solutions.展开更多
The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances （EPS） in anaerobic digested sludge were determined. The tot...The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances （EPS） in anaerobic digested sludge were determined. The total EPS in anaerobic digested sludge were extracted by the cation exchange resin method. Another EPS extraction method, the ceutrifugation and sonication technique was employed to stratify the EPS into three fractions： slime, loosely bound （LB）-EPS, and tightly bound （TB）-EPS from the outside to the inside of the anaerobic digested sludge. Proteins and polysaccharides were dispersed uniformly across the different EPS fractions, and humic-like substances were mainly partitioned in the slime, with TB-EPS second. Protein was the major constituent of the LB-EPS and TB-EPS, and the corresponding ratios ranged from 54.0% to 65.6%. The hydrophobic part in the EPS chemical components was primarily comprised of protein and DNA, while the hydrophilic part was mainly composed of polysaccharide. In the slime, the hydrophobic values of several EPS chemical components （protein, polysaccharide, humic-like substances and DNA） were all below 50%. The protein/polysaccharide ratio had a significant influence on the Zeta potentials and isoelectric point values of the EPS： the greater the protein/polysaccharide ratio of the EPS was, the greater the Zeta potential and the higher the isoelectric point value were. All Zeta potentials of the EPS showed a decreasing trend with increasing pH. The corresponding isoelectric point values （pH） were 2.8 for total EPS, 2.2 for slime, 2.7 for LB-EPS, and 2.6 for TB-EPS. As the ionic strength increased, the Zeta potentials sharply increased and then gradually became constant without charge reversal. In addition, as the temperature increased （〈 40℃）, the apparent viscosity of the EPS decreased monotonically and then gradually became stable between 40 and 60℃.展开更多
In this paper, a series of experiments, including atomic force microscope （AFM）, environmental scanning electron microscope （ESEM）, and core displacement tests were conducted to investigate the effect of polymer s...In this paper, a series of experiments, including atomic force microscope （AFM）, environmental scanning electron microscope （ESEM）, and core displacement tests were conducted to investigate the effect of polymer solution structure on solution properties and oil displacement efficiency. The results show that in the HPAM solution polymer coils were formed and then aggregated into a loose structure, while the HAP2010 solution formed a strong network structure, which would significantly improve the solution viscosity and flow resistance so as to upgrade the capacity of piston-like oil displacement in highly permeable porous media. Meanwhile, the retention of the HAP2010 solution at pore throats were also enhanced, which could reduce water production during subsequent water flooding and enlarge the swept volume during polymer flooding. Therefore, enhancing the interaction among polymer molecules is an effective way to improve the displacement efficiency of polymer solutions in heavy oil reservoirs with high permeability.展开更多
Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic l...Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.展开更多
The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association...The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions.展开更多
The influence of dissolved oxygen content on the oxidative stability of a linked polymer solution (LPS) was studied by micro-filtration, dynamic light scattering and viscosity measurements. The results showed that at ...The influence of dissolved oxygen content on the oxidative stability of a linked polymer solution (LPS) was studied by micro-filtration, dynamic light scattering and viscosity measurements. The results showed that at the same temperature, the degree of the oxidative degradation of the LPS increased and the rapidity of the oxidative degradation was accelerated with the increase of the dissolved oxygen content. Consequently, the size of linked polymer coils (LPCs) of the LPS became small, and the plugging capability of the LPS decreased. At a fixed content of dissolved oxygen, with increasing degradation temperature, almost the same results were observed, namely, an increased degree of oxidative degradation, accelerated rapidity of the oxidative degradation and decreased plugging capacity, with decreased oxidative stability of LPS. At 90 °C, in the presence of oxygen, LPS lost its plugging capability after having been degraded for a period of time. But at 40 °C, LPS with low dissolved oxygen content could be stable for a long time. The decreased plugging ability of LPS after oxidative degradation is mainly caused by the decreased size and number of the LPCs due to the breaking of hydrolyzed polyacrylamide (HPAM) molecule segments and the structural changing of HPAM molecules.展开更多
Solvents have an essential association with polymer solution behavior.However,few researches have been deeply done on this respect.In recent years,our research group focus on the study on effect of solvent properties ...Solvents have an essential association with polymer solution behavior.However,few researches have been deeply done on this respect.In recent years,our research group focus on the study on effect of solvent properties on solution behavior and film condensed state structure for semi-rigid conjugated polymer up till to apply for optoelectronic device.Herein,influence of solvent properties including solubility of solvent,aromaticity,polarity and hydrogen bonds on semi-rigid polymer chain solution behavior,i.e.,single chain conformation,chain shape,size and chains aggregated density were studied by means of static/dynamic laser light scattering(DLS/SLS)and exponential law etc.Effect of solvent properties on condensed state structure of the semi-rigid conjugated polymer film was studied by UV absorption spectroscopy,PL spectroscopy and electron microscopy etc.The essential reasons for the influence were discovered and the mechanism was revealed.It was found that solution behavior with different solvent properties had an essential physical relationship with chains condensed state structure of the semi-rigid conjugated polymers.More importantly,there was a quantitative structure-activity relationship between solution and film.The key to this relationship depended on the interaction between solvent molecules and the semi-rigid conjugated polymer chains.This interaction could also affect optoelectronic devices performance.This study is of great significance to effectively control the condensed state structure of the semirigid conjugated polymers in the process of dynamic evolution from solutions to films.It not only enriches the knowledge and understanding of both semi-rigid conjugated polymer solution behaviors and film condensed state physics based on polymer physics,but also is meaningful to practical application for conjugated polymer and other traditional polymer systems.展开更多
Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinyl alcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves at extremely dilute ...Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinyl alcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves at extremely dilute concentration levels similar to the phenomena observed for many polymer solutions in the early 1950's. Upon observation of the changes of the flow times of pure water in and the wall surface wettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosity abnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymer chains onto the wall surface of viscometer. A theory of adsorption effect based on the Langmuir isotherms was proposed and a mathematical; analysis for data treatment was performed. The theory could adequately describe the existing viscosity data. It seems necessary to correct the viscosity result of dilute polymer solutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.展开更多
Entanglement network is an important structural feature in concentrated polymer solutions and polymer melts,which has a great influe nee on the transie nt rheological behavior and molecular con figurati on evolution.H...Entanglement network is an important structural feature in concentrated polymer solutions and polymer melts,which has a great influe nee on the transie nt rheological behavior and molecular con figurati on evolution.However,the existi ng constitutive models have limitations in describi ng the influe nee of dyn amic entan glement behavior on molecular chain motion,resulti ng in inaccurate descriptions of the transient rheological behavior.Thus,a molecular con figuration evoluti on model for polymer solutions considering the dyn amic entanglement effect is proposed by introducing an intermolecular force that changes with the orientation of the molecular chain in this work.The intermolecular force is introduced by consider!ng the friction coefficient as anisotropic,and the orientation effect is considered by introducing an excluded volume depende nt an isotropic diffusi on.The proposed model can better describe the stress relaxation,stress growth,and dielectric an isotropy of polymer soluti ons compared with the an isotropy FENE model and FENE model.In addition,the in fluence of different model parameters on the transient and steady shear response of polymer soluti on is investigated,and the results show that the in fluence of volume loss on the fricti on anisotropy factor k0 in creases as the solution concen tration in creases.展开更多
Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) ...Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.展开更多
A simple and effective photochemical method was developed for cross-linking of polymer gate dielectrics. Laborious synthetic processes for functionalizing polymer dielectrics with photo-cross-linkable groups were avoi...A simple and effective photochemical method was developed for cross-linking of polymer gate dielectrics. Laborious synthetic processes for functionalizing polymer dielectrics with photo-cross-linkable groups were avoided. The photo-cross-linker, BBP-4, was added into host polymers by simple solution blending process, which was capable of abstracting hydrogen atoms from polymers containing active C--H groups upon exposure to ultraviolet （UV） radiation. The cross-linking can be completed with a relatively long wavelength UV light （365 nm）. The approach has been applied to methacrylate and styrenic polymers such as commercial poly（methylmethacrylate） （PMMA）, poly（iso-butylmethacrylate） （PiBMA） and poly（4-methylstyrene） （PMS）. The cross-linked networks enhanced dielectric properties and solvent resistance of the thin films. The bottom-gate organic field-effect transistors （OFETs） through all solution processes on plastic substrate were fabricated. The OFET devices showed low voltage operation and steep subthreshold swing at relatively small gate dielectric capacitance.展开更多
Near-infrared light(NIR)triggered transdermal drug delivery systems are of great interest due to their on-demand drug release,which enable to enhance drug treatment efficiency as well as reduce side effect.Herein,a NI...Near-infrared light(NIR)triggered transdermal drug delivery systems are of great interest due to their on-demand drug release,which enable to enhance drug treatment efficiency as well as reduce side effect.Herein,a NIR-triggered microneedle(MN)patch array has been fabricated through depositing the photothermal conversion agent and anti-diabetic drug-loaded polymer vesicles with upper critical solution temperature(UCST)into dissolvable polymer matrix.The UCST-type polymer has a clearing point temperature of 41℃ and the drug-loaded polymer vesicles present excellent NIR-triggered and temperature responsive drug release behavior in vitro due to the disassociation of polymer vesicles upon NIR irradiation.After applying MNs to diabetic rats,significant hypoglycemic effect is achieved upon interval NIR irradiation and the blood glucose concentration can decrease to normal state for several hours,which enables to achieve the goal of on-demand drug release.This work suggests that the NIR-triggered MN drug release device has a potential application in the treatment of diabetes,especially for those requiring an active drug release manner.展开更多
To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule...To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.展开更多
An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model stru...An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results展开更多
基金financially supported by the Russian Science Foundation(No.20-13-00038).
文摘Poly(1-butyl-3-vinylimidazolium bromide)is a polymerized ionic liquid(PILs),a relatively new class of materials that combines the attractive properties of ionic liquids(ILs)and polyelectrolytes and finds wide applications.The backbone of this PIL is composed of quaternary imidazolium salts,which are among the most promising and popular ILs.However,little is known about the physicochemical characteristics of the aqueous solutions of this PIL.In this study,we synthesized and characterized samples of this PIL and obtained experimental data on the viscosity,static and dynamic light scattering,and nuclear magnetic resonance diffusometry for aqueous and aqueous KBr solutions with varying polymer contents at T=298.15 K.We discuss the effects of the polymer concentration and salinity on the behavior of the solution.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2023B0101200006)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011926)+1 种基金Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates,Guangzhou 510640,China(South China University of Technology)(No.2023B1212060003)State Key Laboratory of Applied Microbiology Southern China(No.SKLAM008-2022)。
文摘The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.
文摘A novel Ni（Ⅱ） ion-imprinted silica gel polymer was prepared via the surface imprinting technique combined with aqueous solution polymerization by using 2-acrylamido-2-methyl-1-propanesulfonic acid（AMPS） as a functional monomer for the selective separation of Ni（Ⅱ） from aqueous solution. The sorbent showed good chemical and thermal stability. Kinetics studies indicated that the equilibrium adsorption was achieved within 10 min and the adsorption kinetics fitted well with the pseudo-second-order kinetic model. The maximum adsorption capacity of the ion-imprinted polymer towards Ni（Ⅱ） at the optimal p H of 7.0 was 66.22 mg·g^（-1）. The relative selectivity coefficients of the sorbent were 9.23, 15.71, 14.72 and 20.15 for Ni（Ⅱ）/Co（Ⅱ）, Ni（Ⅱ）/Cu（Ⅱ）, Ni（Ⅱ）/Zn（Ⅱ） and Ni（Ⅱ）/Pb（Ⅱ）, respectively. The adsorption isotherm fitted well with Langmuir isotherm model. The thermodynamic results indicated that the adsorption of Ni（Ⅱ） was a spontaneous and endothermic process. The sorbent showed good reusability evidenced by six cycles of adsorption/desorption experiments. The precision of this method is satisfactory. Thus, the prepared sorbent can be considered as a promising sorbent for selective separation of Ni（Ⅱ） in real water samples.
基金Project(51374251)supported by the National Natural Science Foundation of China
文摘A series of low-temperature phase transitions of sodium aluminate solutions were studied by differential scanning calorimetry (DSC) and Raman spectroscopy. The results indicate that NaOH concentration is a primary impact factor for the binary eutectic point and ice melting temperature of sodium aluminate solutions with low NaOH concentration. In addition, the phase transition process of sodium aluminate solutions with low NaOH concentration from 123.15 to 283.15 K is divided into four steps: non-crystal to crystal, ternary eutectic reaction, binary eutectic reaction and ice melt. The projection phase diagram of NaOH-Al(OH)3-H2O system at low temperature was plotted, in which the ternary eutectic temperature for sodium aluminate solutions is 183.15 K.
文摘Behenyl acrylate is a kind of highly efficient pour point depressants. In order to promote theapplication of the pour pint depressant in transportation of crude oils, polybehenyl acrylate was synthesizedby solution polymerization. These conclusions can be drawn from the experimental results that the sequenceof chain transfer constants of four solvents is arranged in the following decreasing order: carbon tetrachloride(6.010-5)>chloroform (2.810-5)>methylbenzene (2.510-5)>tetrachloroethane (1.610-5). The average molecu-lar weight of polybehenyl acrylate mainly depends on the chain transfer constant of the solvents. However, ifthe monomer conversion was higher than 35%, an abnormal phenomenon occurred, resulting in higher aver-age molecular weight of polybehenyl acrylate obtained in methylbenzene solution compared to that obtainedin tetrachloroethane solution. It was attributed to the influence of gelation on the average molecular weight ofpolybehenyl acrylate, which was stronger than the impact of chain transfer in methylbenzene.
文摘The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions among polymer monomers are focused. Extensive simulations show that the dependence of diffusion coefficient D on the polymer concentration c agrees with Phillies equation D-exp （-αc^δ） with a scaling exponent δ≈0.97 which coincides with the experimental one in literature. For increasing nanoparticle size, the scaling prefactor α increases monotonically while the scaling exponent always keeps fixed. Moreover, we also study the diffusion of nanoparticle without hydrodynamic interactions and find that mobility of the nanoparticle slows down, and the scaling exponent is obviously different from the one in experiments, implying that hydrodynamic interactions play a crucial role in the diffusion of a nanoparticle in semidilute polymer solutions.
基金supported by the Fundamental Research Funds for the Central University (No.JC2011-1,TD2010-5)the National Natural Science Foundation of China(No. 51078035, 21177010)the Ph.D Programs Foundation of the Ministry of Education of China (No.20100014110004)
文摘The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances （EPS） in anaerobic digested sludge were determined. The total EPS in anaerobic digested sludge were extracted by the cation exchange resin method. Another EPS extraction method, the ceutrifugation and sonication technique was employed to stratify the EPS into three fractions： slime, loosely bound （LB）-EPS, and tightly bound （TB）-EPS from the outside to the inside of the anaerobic digested sludge. Proteins and polysaccharides were dispersed uniformly across the different EPS fractions, and humic-like substances were mainly partitioned in the slime, with TB-EPS second. Protein was the major constituent of the LB-EPS and TB-EPS, and the corresponding ratios ranged from 54.0% to 65.6%. The hydrophobic part in the EPS chemical components was primarily comprised of protein and DNA, while the hydrophilic part was mainly composed of polysaccharide. In the slime, the hydrophobic values of several EPS chemical components （protein, polysaccharide, humic-like substances and DNA） were all below 50%. The protein/polysaccharide ratio had a significant influence on the Zeta potentials and isoelectric point values of the EPS： the greater the protein/polysaccharide ratio of the EPS was, the greater the Zeta potential and the higher the isoelectric point value were. All Zeta potentials of the EPS showed a decreasing trend with increasing pH. The corresponding isoelectric point values （pH） were 2.8 for total EPS, 2.2 for slime, 2.7 for LB-EPS, and 2.6 for TB-EPS. As the ionic strength increased, the Zeta potentials sharply increased and then gradually became constant without charge reversal. In addition, as the temperature increased （〈 40℃）, the apparent viscosity of the EPS decreased monotonically and then gradually became stable between 40 and 60℃.
基金supported by the National Science and Technology Major Project (2011ZX05024-004)National High Technology Research and Development Program of China (863 Program: 2007AA090701-3)
文摘In this paper, a series of experiments, including atomic force microscope （AFM）, environmental scanning electron microscope （ESEM）, and core displacement tests were conducted to investigate the effect of polymer solution structure on solution properties and oil displacement efficiency. The results show that in the HPAM solution polymer coils were formed and then aggregated into a loose structure, while the HAP2010 solution formed a strong network structure, which would significantly improve the solution viscosity and flow resistance so as to upgrade the capacity of piston-like oil displacement in highly permeable porous media. Meanwhile, the retention of the HAP2010 solution at pore throats were also enhanced, which could reduce water production during subsequent water flooding and enlarge the swept volume during polymer flooding. Therefore, enhancing the interaction among polymer molecules is an effective way to improve the displacement efficiency of polymer solutions in heavy oil reservoirs with high permeability.
基金financial support from the National Key Technology R&D Program in the 12th Five Year Plan of PetroChina (No: 2011ZX05010-003-02)the National Key Technology R&D Program in the 12th Five Year Plan of CNOOC (No: 2011ZX05024-04-05-03)
文摘Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.
基金This work was supported by the Chinese National Basic Research Project "Macromolecular Condensed State" and National Natural Science Foundation of China
文摘The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions.
文摘The influence of dissolved oxygen content on the oxidative stability of a linked polymer solution (LPS) was studied by micro-filtration, dynamic light scattering and viscosity measurements. The results showed that at the same temperature, the degree of the oxidative degradation of the LPS increased and the rapidity of the oxidative degradation was accelerated with the increase of the dissolved oxygen content. Consequently, the size of linked polymer coils (LPCs) of the LPS became small, and the plugging capability of the LPS decreased. At a fixed content of dissolved oxygen, with increasing degradation temperature, almost the same results were observed, namely, an increased degree of oxidative degradation, accelerated rapidity of the oxidative degradation and decreased plugging capacity, with decreased oxidative stability of LPS. At 90 °C, in the presence of oxygen, LPS lost its plugging capability after having been degraded for a period of time. But at 40 °C, LPS with low dissolved oxygen content could be stable for a long time. The decreased plugging ability of LPS after oxidative degradation is mainly caused by the decreased size and number of the LPCs due to the breaking of hydrolyzed polyacrylamide (HPAM) molecule segments and the structural changing of HPAM molecules.
基金the National Natural Science Foundation of China(Nos.91333103 and 21574053).
文摘Solvents have an essential association with polymer solution behavior.However,few researches have been deeply done on this respect.In recent years,our research group focus on the study on effect of solvent properties on solution behavior and film condensed state structure for semi-rigid conjugated polymer up till to apply for optoelectronic device.Herein,influence of solvent properties including solubility of solvent,aromaticity,polarity and hydrogen bonds on semi-rigid polymer chain solution behavior,i.e.,single chain conformation,chain shape,size and chains aggregated density were studied by means of static/dynamic laser light scattering(DLS/SLS)and exponential law etc.Effect of solvent properties on condensed state structure of the semi-rigid conjugated polymer film was studied by UV absorption spectroscopy,PL spectroscopy and electron microscopy etc.The essential reasons for the influence were discovered and the mechanism was revealed.It was found that solution behavior with different solvent properties had an essential physical relationship with chains condensed state structure of the semi-rigid conjugated polymers.More importantly,there was a quantitative structure-activity relationship between solution and film.The key to this relationship depended on the interaction between solvent molecules and the semi-rigid conjugated polymer chains.This interaction could also affect optoelectronic devices performance.This study is of great significance to effectively control the condensed state structure of the semirigid conjugated polymers in the process of dynamic evolution from solutions to films.It not only enriches the knowledge and understanding of both semi-rigid conjugated polymer solution behaviors and film condensed state physics based on polymer physics,but also is meaningful to practical application for conjugated polymer and other traditional polymer systems.
基金This work was supported by the National Basic Research Project-Macromolecular Condensed State,and the National Natural Science Foundationof China
文摘Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinyl alcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves at extremely dilute concentration levels similar to the phenomena observed for many polymer solutions in the early 1950's. Upon observation of the changes of the flow times of pure water in and the wall surface wettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosity abnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymer chains onto the wall surface of viscometer. A theory of adsorption effect based on the Langmuir isotherms was proposed and a mathematical; analysis for data treatment was performed. The theory could adequately describe the existing viscosity data. It seems necessary to correct the viscosity result of dilute polymer solutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.
基金from the National Natural Science Foundation of China(Nos.52005194,51635006,and 51675199)China Postdoctoral Science Foundatio n(No.2019M662615)+1 种基金the National Program on Key Basic Research Project(No.2019YFB1704900)the Fundamental Research Funds for the Central Universities’ HUST(No.2020JYCXJJ055).
文摘Entanglement network is an important structural feature in concentrated polymer solutions and polymer melts,which has a great influe nee on the transie nt rheological behavior and molecular con figurati on evolution.However,the existi ng constitutive models have limitations in describi ng the influe nee of dyn amic entan glement behavior on molecular chain motion,resulti ng in inaccurate descriptions of the transient rheological behavior.Thus,a molecular con figuration evoluti on model for polymer solutions considering the dyn amic entanglement effect is proposed by introducing an intermolecular force that changes with the orientation of the molecular chain in this work.The intermolecular force is introduced by consider!ng the friction coefficient as anisotropic,and the orientation effect is considered by introducing an excluded volume depende nt an isotropic diffusi on.The proposed model can better describe the stress relaxation,stress growth,and dielectric an isotropy of polymer soluti ons compared with the an isotropy FENE model and FENE model.In addition,the in fluence of different model parameters on the transient and steady shear response of polymer soluti on is investigated,and the results show that the in fluence of volume loss on the fricti on anisotropy factor k0 in creases as the solution concen tration in creases.
基金The authors gratefully a.cknowledge financial supportfrom th6 Natiol-al Natural Science Foundatiol- of CI-h-a. The number of
文摘Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.
基金financially supported by the National Natural Science Foundation of China (Nos.21674060,21274087,61674102,and 61334008)National Key R&D Program (No.2016YFB0401100)
文摘A simple and effective photochemical method was developed for cross-linking of polymer gate dielectrics. Laborious synthetic processes for functionalizing polymer dielectrics with photo-cross-linkable groups were avoided. The photo-cross-linker, BBP-4, was added into host polymers by simple solution blending process, which was capable of abstracting hydrogen atoms from polymers containing active C--H groups upon exposure to ultraviolet （UV） radiation. The cross-linking can be completed with a relatively long wavelength UV light （365 nm）. The approach has been applied to methacrylate and styrenic polymers such as commercial poly（methylmethacrylate） （PMMA）, poly（iso-butylmethacrylate） （PiBMA） and poly（4-methylstyrene） （PMS）. The cross-linked networks enhanced dielectric properties and solvent resistance of the thin films. The bottom-gate organic field-effect transistors （OFETs） through all solution processes on plastic substrate were fabricated. The OFET devices showed low voltage operation and steep subthreshold swing at relatively small gate dielectric capacitance.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LY20E030005)the Opening Project of Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices(No.PMND201905)。
文摘Near-infrared light(NIR)triggered transdermal drug delivery systems are of great interest due to their on-demand drug release,which enable to enhance drug treatment efficiency as well as reduce side effect.Herein,a NIR-triggered microneedle(MN)patch array has been fabricated through depositing the photothermal conversion agent and anti-diabetic drug-loaded polymer vesicles with upper critical solution temperature(UCST)into dissolvable polymer matrix.The UCST-type polymer has a clearing point temperature of 41℃ and the drug-loaded polymer vesicles present excellent NIR-triggered and temperature responsive drug release behavior in vitro due to the disassociation of polymer vesicles upon NIR irradiation.After applying MNs to diabetic rats,significant hypoglycemic effect is achieved upon interval NIR irradiation and the blood glucose concentration can decrease to normal state for several hours,which enables to achieve the goal of on-demand drug release.This work suggests that the NIR-triggered MN drug release device has a potential application in the treatment of diabetes,especially for those requiring an active drug release manner.
文摘To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.
文摘An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results
