Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interfac...Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interface anchoring,and inorganic particles have gained extensive attention recently owing to their large interfacial desorption energy,while their low affinity to bulk components is a drawback.In this study,an interfacial atom transfer radical polymerization(ATRP)technique was employed to grow polystyrene(PS)and poly(2-hydroxyethyl methacrylate)(PHEMA)simultaneously on different hemispheres of Br-functionalized SiO_(2) nanoparticles to stabilize a Pickering emulsion,whereby a brush-type Janus nanoparticle(SiO_(2)@JNP)was developed.The polymer brushes were well-characterized,and the Janus feature was validated by transmission electron microscope(TEM)observation of the sole hemisphere grafting of SiO_(2)-PS as a control sample.SiO_(2)@JNP was demonstrated to be an efficient compatibilizer for a PS/poly(methyl methacrylate)(PMMA)immiscible blend,and the droplet-matrix morphology was significantly refined.The mechanical strength and toughness of the blend were synchronously enhanced at a low content SiO_(2)@JNP optimized~0.9 wt%,with the tensile strength,elongation at break and impact strength increased by 17.7%,26.6%and 19.6%,respectively.This enhancement may be attributed to the entanglements between the grafted polymer brushes and individual components that improve the particle-bulk phase affinity and enforce interfacial adhesion.展开更多
Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM...Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.展开更多
This paper focuses on the effects of the PSt content of polystyrene (PSt)-poly (dimethylsiloxane) (PDMS) interpenetrateing network (IPN) polymer membranes, on the pervaporation (PV) characteristics during the removal ...This paper focuses on the effects of the PSt content of polystyrene (PSt)-poly (dimethylsiloxane) (PDMS) interpenetrateing network (IPN) polymer membranes, on the pervaporation (PV) characteristics during the removal of benzene from an aqueous solution of dilute benzene. When an aqueous solution of 0.05wt% benzene was permeated through the PSt-PDMS IPN membranes, they showed high benzene/water selectivity. Both the permeability and the benzene/water selectivity of the membranes were enhanced with increasing PSt content in the PSt-PDMS IPN membrane. The physicochemical mechanism of permeation and separation through the PSt-PDMS IPN membranes during PV is also discussed. The best normalized permeation rate, separation factor for benzene selectivity, and PV separation index of the PSt-PDMS IPN membrane were 1.27 × 10-6 kgm (m2hr)-1, 3293, and 41821, respectively. These PV characteristics are discussed from the viewpoint of the chemical and physical structure of the PSt-PDMS IPN membranes.展开更多
The adsorption of linear poly(N-isopropylacrylamide) (PNIPAM) chains on surfactant-free polystyrene (PS) nanoparticles was used as a model system to study the hydrophobic adsorption of polymer on the surface, because ...The adsorption of linear poly(N-isopropylacrylamide) (PNIPAM) chains on surfactant-free polystyrene (PS) nanoparticles was used as a model system to study the hydrophobic adsorption of polymer on the surface, because the hydrophobility of PNIPAM can be continuously varied by a small temperature change. The adsorption was investigated by a combination of static and dynamic laser light scattering (LLS) measurements. In static LLS, the absolute excess scattered light intensity led to the amount of PNIPAM adsorbed on the surface. In dynamic LLS, the hydrodynamic thickness of the adsorbed PNIPAM layer was accurately measured. For a given particle concentration, the adsorption increases as the PNIPAM concentration and the incubation temperature increase. The average density of the adsorbed PNIPAM layer is reciprocally proportional to the number of the PNIPAM chains on the surface, revealing a simple scaling of the chain density distribution. The adsorption follows the Langmuir's isotherm. The enthalpy change estimated from the adsorption at 25 degrees C and 30 degrees C is slightly positive, indicating that the adsorption involves the coil-to-globule transition of the chains on the surface.展开更多
A hydrophilic/hydrophobic interpenetrating polymer network （IPN） of poly （vinyl alcohol） / polystyrene was prepared by conversion of the IPN of poly （vinyl acetate）/polystyrene. The hydrophilic/hydrophobic IPN w...A hydrophilic/hydrophobic interpenetrating polymer network （IPN） of poly （vinyl alcohol） / polystyrene was prepared by conversion of the IPN of poly （vinyl acetate）/polystyrene. The hydrophilic/hydrophobic IPN was characterized by FT-IR and DSC, and the swelling ratios of the IPN in different solvents were measured.展开更多
Dielectric elastomers(DEs)have drawn much attention owing to their application prospects in artificial muscles and soft robotics,it is still a big challenge to prepare DEs with high electromechanical performances.This...Dielectric elastomers(DEs)have drawn much attention owing to their application prospects in artificial muscles and soft robotics,it is still a big challenge to prepare DEs with high electromechanical performances.This work reports a highly stretchable poly(thioether)-b-polysiloxane-b-poly(thioether)triblock copolymer based homogenous DEs with high electromechanical properties.The triblock copolymer(PSiPGE)was synthesized through the ring-opening polymerization(ROP)of phenyl glycidyl ether(PGE)and carbonyl sulfide(COS)catalyzed by silicon alkoxides.The dipoles(benzene rings)on the side groups of PSiPGE improved the dipole polarizations and the phase separation structure of this triblock copolymer enhanced the interfacial polarizations between poly(thioether)and polysiloxane,and thus improving the dielectric constant(ε',up to 5.8).In addition,the PSiPGE exhibited low elastic modulus(Y,0.04 MPa),and thus possessed high electromechanical sensitivity(β,~145 MPa^(-1)) which is much higher than that of most homogenous DEs.This work provides a new strategy to construct homogenous DEs with excellent electromechanical performances,leading to a greater application aspect in the actuated devices.展开更多
New siloxane and sulfone containing poly（benzimidazole/sulfone/siloxane/amide） （PBSSA） has been prepared for the formation of hybrid membranes （PBSSA/PS-S/SiNPs） with sulfonated polystyrene （PS-S） and 0.1 wt%-...New siloxane and sulfone containing poly（benzimidazole/sulfone/siloxane/amide） （PBSSA） has been prepared for the formation of hybrid membranes （PBSSA/PS-S/SiNPs） with sulfonated polystyrene （PS-S） and 0.1 wt%-2 wt% silica nanoparticles （SiNPs）. Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSAJPS-S/SiNPs nanocomposites increased from 207℃ to 215 ℃. The membranes also had higher ion exchange capacity （IEC） around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10-2.34 S/cm in a wide range of humidity values at 80 ~C which was higher than that of perfluorinated Nafion 117 membrane （1.1 × 10^-1 S/cm） at 80 ~C （94% RH）. A H2/O2 fuel cell using the PBSSA/PS-S/SiNP 2 （IEC 3.01 retool/g） showed better performance than that of Nation 117 at 40 ℃ and 30% RH.展开更多
The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional 'living' PEO chains with vinyl benzyl ...The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional 'living' PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as 'selective dissolvation', was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the copolymerization were also studied. The results indicate that the feed ratio of macromer to styrene (M/S) was the most important factor in determining the composition of the copolymers. Thus a series of PS-g-PEO with a wide range of bulk compositions were obtained simply by adjusting the value of M/S. As clearly indicated by transmission electron microscopy, this amphiphilic graft copolymers may readily form microphase separated structures.展开更多
The polyelectrolyte complex formed from the polyanion and polycation was studied by turbidimetry, static and electrophoretic light scattering, and elementary analysis. Sodium salts of polyacrylate （PA） and heparin ...The polyelectrolyte complex formed from the polyanion and polycation was studied by turbidimetry, static and electrophoretic light scattering, and elementary analysis. Sodium salts of polyacrylate （PA） and heparin （Hep） were chosen as the polyanion, and hydrochloric salts of poly（vinyl amine） （PVA） and chitosan （Chts） as the polycation. Although these vinyl polymers and polysaccharides have remarkably different backbone chemical structures and linear charge densities, all the four combinations PA-PVA, PA-Chts, Hep-PVA, and Hep-Chts provide almost stoichiometric polyelectrolyte complexes which are slightly charged owing to the adsorption of the excess polyelectrolyte component onto the neutral complex. The charges stabilize the complex colloids in aqueous solution of a non-stoichiometric mixture, and the aggregation number of the complex colloids increases with approaching to the stoichiometric mixing ratio. The mixing ratio dependence of the aggregation number for the four complexes is explained by the model proposed in the previous study.展开更多
Polysubstituted cyclopropanes were efficiently prepared with poly（ethylene glycol）（PEG） as soluble support. The reaction of PEG-supported pyridinium ylide with arylidenemalononitrile（R=CN） or ethyl arylidenecyan...Polysubstituted cyclopropanes were efficiently prepared with poly（ethylene glycol）（PEG） as soluble support. The reaction of PEG-supported pyridinium ylide with arylidenemalononitrile（R=CN） or ethyl arylidenecyanoa-cetate（R=COOEt） in the presence of triethylamine（TEA） afforded PEG-supported cyclopropanecarboxylates, which were cleaved by 1% KCN/EtOH to obtain polysubstituted cyclopropanes with exclusive trans-selectivity and good yields.展开更多
Highly ordered honeycomb-patterned polystyrene (PS)/poly(ethylene glycol) (PEG) films were prepared by a water-assisted method using an improved setup, which facilitated the formation of films with higher regularity, ...Highly ordered honeycomb-patterned polystyrene (PS)/poly(ethylene glycol) (PEG) films were prepared by a water-assisted method using an improved setup, which facilitated the formation of films with higher regularity, better reproducibility, and larger area of honeycomb structures. Surface aggregation of hydrophilic PEG and adsorption of bovine serum albumin (BSA) on the honeycomb-patterned films were investigated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to observe the surface morphologies of the films before and after being rinsed with water. As confirmed by the FESEM images and the AFM phase images, PEG was enriched in the pores and could be gradually removed by water. The adsorption of fluorescence-labeled BSA on the films was studied in visual form using laser scanning confocal microscopy. Results clearly demonstrated that the protein-resistant PEG was selectively enriched in the pores. This water-assisted method may be a latent tool to prepare honeycomb-patterned biofunctional surfaces.展开更多
Narrowly distributed polystyrene-g-p(N-isopropylacrylamide) (PSt-g-PNIPAM) was prepared by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using the brominated polystyrene as macroinitiator and Cu...Narrowly distributed polystyrene-g-p(N-isopropylacrylamide) (PSt-g-PNIPAM) was prepared by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using the brominated polystyrene as macroinitiator and CuCl combined with hexamethyltriethylenetetramine as catalyst. Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of PSt-g-PNIPAM. The gel permeation chromatography (GPC) showed that the graft copoly- mer had a single distribution peak with molecular weight, Mn (g/mol) of 19815 g/mol (using polystyrene as the standard). Differential scanning calorimetry (DSC) revealed that due to both effects of hydro- phobic isopropyl groups and hydrogen bonds in the amide group, the glass transition temperature (Tg) of PSt-g-PNIPAM enhanced 16.0 ℃ compared to the Tg of the polystyrene.展开更多
Mucopolysaccharidoses(MPS)are a group of rare inborn errors of metabolism caused by defective lysosomal enzymes which prevent cells from degrading and recycling certain carbohydrates and fats,resulting in the storage ...Mucopolysaccharidoses(MPS)are a group of rare inborn errors of metabolism caused by defective lysosomal enzymes which prevent cells from degrading and recycling certain carbohydrates and fats,resulting in the storage of glycosaminoglycans in cells throughout the body.This leads to multisystem abnormalities involving bone,connective tissues,brain,blood,spinal cord,skin,and other tissues.展开更多
Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH b...Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.展开更多
In this research, a surface imprinting strategy has been adopted in protein imprinting. Bovine hemo-globin surface-imprinted polystyrene (PS) nanoparticles with magnetic susceptibility have been syn-thesized through m...In this research, a surface imprinting strategy has been adopted in protein imprinting. Bovine hemo-globin surface-imprinted polystyrene (PS) nanoparticles with magnetic susceptibility have been syn-thesized through multistage core-shell polymerization system using 3-aminophenylboronic acid (APBA) as functional and cross-linking monomers. Superparamagnetic molecularly imprinted polystyrene nanospheres with poly(APBA) thin films have been synthesized and used for the first time for protein molecular imprinting in an aqueous solution. The magnetic susceptibility is imparted through the successful encapsulation of Fe3O4 nanoparticles. The morphology, adsorption, and recognition prop-erties of superparamagnetic molecularly imprinted polymers (MIPs) have been investigated using transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Rebinding experimental results show that poly(APBA) MIPs-coated superparamagnetic PS nanoparticles have high adsorption capacity for template protein bovine hemoglobin and compara-tively low nonspecific adsorption. The imprinted superparamagnetic nanoparticles could easily reach the adsorption equilibrium and achieve magnetic separation in an external magnetic field, thus avoid-ing some problems of the bulk polymer.展开更多
To advance commercial application of forward osmosis （FO）, we investigated the effects of two additives on the performance of polysulfone （PSf） based FO membranes： one is poly（ethylene glycol） （PEG）, and anot...To advance commercial application of forward osmosis （FO）, we investigated the effects of two additives on the performance of polysulfone （PSf） based FO membranes： one is poly（ethylene glycol） （PEG）, and another is PSf grafted with PEG methyl ether methacrylate （PSf-g-PEGMA）. PSf blended with PEG or PSf-g- PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaC1 （1 mol·L^-1） and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSfwith 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L·m^-2·h^-1 than the commercial HTI membranes （6-8 L·m^-2·h^-1） under the FO mode. Our study suggests that hydrophobic interface is very important for the formation ofpolyamide, and a small amount of PSf- g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.展开更多
Ionic conductive hydrogels(ICHs)prepared from natural bioresources are promising candidates for constructing flexible electronics for both commercialization and environmental sustainability due to their intrinsic char...Ionic conductive hydrogels(ICHs)prepared from natural bioresources are promising candidates for constructing flexible electronics for both commercialization and environmental sustainability due to their intrinsic characteristics.However,simultaneous realization of high stiffness,toughness,conductivity,and multifunctionality while ensuring processing simplicity is extremely challenging.Here,a poly(ionic liquid)(PIL)-macromolecule functionalization strategy within a NaOH/urea system is proposed to construct high-performance and versatile polysaccharide-based ICHs(e.g.,cellulosic ICHs).In this strategy,the elaborately designed“soft”(PIL chains)and“hard”(cellulose backbone)structures as well as the dynamic covalent and noncovalent bonds of the cross-linked networks endow the hydrogel with high mechanical strength(9.46±0.23 MPa compressive modulus),exceptional stretchability(214.3%),and toughness(3.64±0.12 MJ m^(−3)).Ingeniously,due to the inherent conductivity,design flexibility,and functional compatibility of the PILs,the hydrogels exhibit high conductivity(6.54±0.17 mS cm^(−1)),self-healing ability(94.5%±2.0%efficiency),antibacterial properties,freezing resistance,water retention,and recyclability.Interestingly,this strategy is extended to fabricate diverse hydrogels from various polysaccharides,including agar,alginate,hyaluronic acid,and guar gum.In addition,multimodal sensing(strain,temperature,and humidity)is realized based on the stimulus-responsive characteristics of the hydrogels.This strategy opens new perspectives for the design of biomass-based hydrogels and beyond.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22172028,21903015,and 22403017)Natural Science Foundation of Fujian Province of China(No.2022J05041)。
文摘Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interface anchoring,and inorganic particles have gained extensive attention recently owing to their large interfacial desorption energy,while their low affinity to bulk components is a drawback.In this study,an interfacial atom transfer radical polymerization(ATRP)technique was employed to grow polystyrene(PS)and poly(2-hydroxyethyl methacrylate)(PHEMA)simultaneously on different hemispheres of Br-functionalized SiO_(2) nanoparticles to stabilize a Pickering emulsion,whereby a brush-type Janus nanoparticle(SiO_(2)@JNP)was developed.The polymer brushes were well-characterized,and the Janus feature was validated by transmission electron microscope(TEM)observation of the sole hemisphere grafting of SiO_(2)-PS as a control sample.SiO_(2)@JNP was demonstrated to be an efficient compatibilizer for a PS/poly(methyl methacrylate)(PMMA)immiscible blend,and the droplet-matrix morphology was significantly refined.The mechanical strength and toughness of the blend were synchronously enhanced at a low content SiO_(2)@JNP optimized~0.9 wt%,with the tensile strength,elongation at break and impact strength increased by 17.7%,26.6%and 19.6%,respectively.This enhancement may be attributed to the entanglements between the grafted polymer brushes and individual components that improve the particle-bulk phase affinity and enforce interfacial adhesion.
基金This work was supported by the National Natural Science Foundation of China (No. 50390090).
文摘Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.
文摘This paper focuses on the effects of the PSt content of polystyrene (PSt)-poly (dimethylsiloxane) (PDMS) interpenetrateing network (IPN) polymer membranes, on the pervaporation (PV) characteristics during the removal of benzene from an aqueous solution of dilute benzene. When an aqueous solution of 0.05wt% benzene was permeated through the PSt-PDMS IPN membranes, they showed high benzene/water selectivity. Both the permeability and the benzene/water selectivity of the membranes were enhanced with increasing PSt content in the PSt-PDMS IPN membrane. The physicochemical mechanism of permeation and separation through the PSt-PDMS IPN membranes during PV is also discussed. The best normalized permeation rate, separation factor for benzene selectivity, and PV separation index of the PSt-PDMS IPN membrane were 1.27 × 10-6 kgm (m2hr)-1, 3293, and 41821, respectively. These PV characteristics are discussed from the viewpoint of the chemical and physical structure of the PSt-PDMS IPN membranes.
文摘The adsorption of linear poly(N-isopropylacrylamide) (PNIPAM) chains on surfactant-free polystyrene (PS) nanoparticles was used as a model system to study the hydrophobic adsorption of polymer on the surface, because the hydrophobility of PNIPAM can be continuously varied by a small temperature change. The adsorption was investigated by a combination of static and dynamic laser light scattering (LLS) measurements. In static LLS, the absolute excess scattered light intensity led to the amount of PNIPAM adsorbed on the surface. In dynamic LLS, the hydrodynamic thickness of the adsorbed PNIPAM layer was accurately measured. For a given particle concentration, the adsorption increases as the PNIPAM concentration and the incubation temperature increase. The average density of the adsorbed PNIPAM layer is reciprocally proportional to the number of the PNIPAM chains on the surface, revealing a simple scaling of the chain density distribution. The adsorption follows the Langmuir's isotherm. The enthalpy change estimated from the adsorption at 25 degrees C and 30 degrees C is slightly positive, indicating that the adsorption involves the coil-to-globule transition of the chains on the surface.
基金supported by the National Natural Science Foundation of China(No.20474015)the Scientific Research Fund of Hunan Provincial Education Department(No.04A029).
文摘A hydrophilic/hydrophobic interpenetrating polymer network （IPN） of poly （vinyl alcohol） / polystyrene was prepared by conversion of the IPN of poly （vinyl acetate）/polystyrene. The hydrophilic/hydrophobic IPN was characterized by FT-IR and DSC, and the swelling ratios of the IPN in different solvents were measured.
基金National Natural Science Foundation of China(Nos.51973190 and 21774108)Zhejiang Provincial Department of Science and Technology(No.2020R52006)for financial supports。
文摘Dielectric elastomers(DEs)have drawn much attention owing to their application prospects in artificial muscles and soft robotics,it is still a big challenge to prepare DEs with high electromechanical performances.This work reports a highly stretchable poly(thioether)-b-polysiloxane-b-poly(thioether)triblock copolymer based homogenous DEs with high electromechanical properties.The triblock copolymer(PSiPGE)was synthesized through the ring-opening polymerization(ROP)of phenyl glycidyl ether(PGE)and carbonyl sulfide(COS)catalyzed by silicon alkoxides.The dipoles(benzene rings)on the side groups of PSiPGE improved the dipole polarizations and the phase separation structure of this triblock copolymer enhanced the interfacial polarizations between poly(thioether)and polysiloxane,and thus improving the dielectric constant(ε',up to 5.8).In addition,the PSiPGE exhibited low elastic modulus(Y,0.04 MPa),and thus possessed high electromechanical sensitivity(β,~145 MPa^(-1)) which is much higher than that of most homogenous DEs.This work provides a new strategy to construct homogenous DEs with excellent electromechanical performances,leading to a greater application aspect in the actuated devices.
文摘New siloxane and sulfone containing poly（benzimidazole/sulfone/siloxane/amide） （PBSSA） has been prepared for the formation of hybrid membranes （PBSSA/PS-S/SiNPs） with sulfonated polystyrene （PS-S） and 0.1 wt%-2 wt% silica nanoparticles （SiNPs）. Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSAJPS-S/SiNPs nanocomposites increased from 207℃ to 215 ℃. The membranes also had higher ion exchange capacity （IEC） around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10-2.34 S/cm in a wide range of humidity values at 80 ~C which was higher than that of perfluorinated Nafion 117 membrane （1.1 × 10^-1 S/cm） at 80 ~C （94% RH）. A H2/O2 fuel cell using the PBSSA/PS-S/SiNP 2 （IEC 3.01 retool/g） showed better performance than that of Nation 117 at 40 ℃ and 30% RH.
基金Supported by the National Natural Science Foundation of China The State Education Commission of China
文摘The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional 'living' PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as 'selective dissolvation', was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the copolymerization were also studied. The results indicate that the feed ratio of macromer to styrene (M/S) was the most important factor in determining the composition of the copolymers. Thus a series of PS-g-PEO with a wide range of bulk compositions were obtained simply by adjusting the value of M/S. As clearly indicated by transmission electron microscopy, this amphiphilic graft copolymers may readily form microphase separated structures.
基金supported by the a Grant-in-Aid for Scientific Research (No. 23350055) from the Japan Society for the Promotion of Science
文摘The polyelectrolyte complex formed from the polyanion and polycation was studied by turbidimetry, static and electrophoretic light scattering, and elementary analysis. Sodium salts of polyacrylate （PA） and heparin （Hep） were chosen as the polyanion, and hydrochloric salts of poly（vinyl amine） （PVA） and chitosan （Chts） as the polycation. Although these vinyl polymers and polysaccharides have remarkably different backbone chemical structures and linear charge densities, all the four combinations PA-PVA, PA-Chts, Hep-PVA, and Hep-Chts provide almost stoichiometric polyelectrolyte complexes which are slightly charged owing to the adsorption of the excess polyelectrolyte component onto the neutral complex. The charges stabilize the complex colloids in aqueous solution of a non-stoichiometric mixture, and the aggregation number of the complex colloids increases with approaching to the stoichiometric mixing ratio. The mixing ratio dependence of the aggregation number for the four complexes is explained by the model proposed in the previous study.
基金Supported by the National High Technology Research and Development Program of China(No.2009AA03Z420)the Natural Science Foundation of Hubei Province of China(Nos.2007ABA031,2008CDA078)
文摘Polysubstituted cyclopropanes were efficiently prepared with poly（ethylene glycol）（PEG） as soluble support. The reaction of PEG-supported pyridinium ylide with arylidenemalononitrile（R=CN） or ethyl arylidenecyanoa-cetate（R=COOEt） in the presence of triethylamine（TEA） afforded PEG-supported cyclopropanecarboxylates, which were cleaved by 1% KCN/EtOH to obtain polysubstituted cyclopropanes with exclusive trans-selectivity and good yields.
基金Supported by the National Natural Science Foundation of China (Grant No. 50803053)the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 50625309)+1 种基金the National Postdoctoral Science Foundation of China (Grant Nos. 20070421172 & 20081466)the National Undergradu-ate Innovative Test Program
文摘Highly ordered honeycomb-patterned polystyrene (PS)/poly(ethylene glycol) (PEG) films were prepared by a water-assisted method using an improved setup, which facilitated the formation of films with higher regularity, better reproducibility, and larger area of honeycomb structures. Surface aggregation of hydrophilic PEG and adsorption of bovine serum albumin (BSA) on the honeycomb-patterned films were investigated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to observe the surface morphologies of the films before and after being rinsed with water. As confirmed by the FESEM images and the AFM phase images, PEG was enriched in the pores and could be gradually removed by water. The adsorption of fluorescence-labeled BSA on the films was studied in visual form using laser scanning confocal microscopy. Results clearly demonstrated that the protein-resistant PEG was selectively enriched in the pores. This water-assisted method may be a latent tool to prepare honeycomb-patterned biofunctional surfaces.
文摘Narrowly distributed polystyrene-g-p(N-isopropylacrylamide) (PSt-g-PNIPAM) was prepared by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using the brominated polystyrene as macroinitiator and CuCl combined with hexamethyltriethylenetetramine as catalyst. Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of PSt-g-PNIPAM. The gel permeation chromatography (GPC) showed that the graft copoly- mer had a single distribution peak with molecular weight, Mn (g/mol) of 19815 g/mol (using polystyrene as the standard). Differential scanning calorimetry (DSC) revealed that due to both effects of hydro- phobic isopropyl groups and hydrogen bonds in the amide group, the glass transition temperature (Tg) of PSt-g-PNIPAM enhanced 16.0 ℃ compared to the Tg of the polystyrene.
文摘Mucopolysaccharidoses(MPS)are a group of rare inborn errors of metabolism caused by defective lysosomal enzymes which prevent cells from degrading and recycling certain carbohydrates and fats,resulting in the storage of glycosaminoglycans in cells throughout the body.This leads to multisystem abnormalities involving bone,connective tissues,brain,blood,spinal cord,skin,and other tissues.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.22278318 and 21878230).
文摘Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.
基金Supported by the National High-Tech Research & Development Program of China (Grant No. 2007AA10Z432)the National Basic Research Program (Grant No. 2007CB914100)+1 种基金the National Natural Science Foundation of China (Grant Nos. 20675040 & 20875050)the Natural Science Foundation of Tianjin (Grant No. 07JCYBJC00500)
文摘In this research, a surface imprinting strategy has been adopted in protein imprinting. Bovine hemo-globin surface-imprinted polystyrene (PS) nanoparticles with magnetic susceptibility have been syn-thesized through multistage core-shell polymerization system using 3-aminophenylboronic acid (APBA) as functional and cross-linking monomers. Superparamagnetic molecularly imprinted polystyrene nanospheres with poly(APBA) thin films have been synthesized and used for the first time for protein molecular imprinting in an aqueous solution. The magnetic susceptibility is imparted through the successful encapsulation of Fe3O4 nanoparticles. The morphology, adsorption, and recognition prop-erties of superparamagnetic molecularly imprinted polymers (MIPs) have been investigated using transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Rebinding experimental results show that poly(APBA) MIPs-coated superparamagnetic PS nanoparticles have high adsorption capacity for template protein bovine hemoglobin and compara-tively low nonspecific adsorption. The imprinted superparamagnetic nanoparticles could easily reach the adsorption equilibrium and achieve magnetic separation in an external magnetic field, thus avoid-ing some problems of the bulk polymer.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 51278317）. We would like to express our special thanks to Prof. Elimelech and his group members at Yale University （New Haven, CN, USA） for guidance on FO experimental setups and interfacial polymerization.
文摘To advance commercial application of forward osmosis （FO）, we investigated the effects of two additives on the performance of polysulfone （PSf） based FO membranes： one is poly（ethylene glycol） （PEG）, and another is PSf grafted with PEG methyl ether methacrylate （PSf-g-PEGMA）. PSf blended with PEG or PSf-g- PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaC1 （1 mol·L^-1） and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSfwith 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L·m^-2·h^-1 than the commercial HTI membranes （6-8 L·m^-2·h^-1） under the FO mode. Our study suggests that hydrophobic interface is very important for the formation ofpolyamide, and a small amount of PSf- g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.
基金National Natural Science Foundation of China,Grant/Award Numbers:22378247,22308283International Joint Research Center for Biomass Chemistry and Materials,Shaanxi International Science and Technology Cooperation Base,Grant/Award Number:2018GHJD-19+1 种基金Shaanxi Qin Chuangyuan Project of“Scientist+Engineer”team construction,Grant/Award Number:2022KXJ-135Shaanxi Qin Chuangyuan Project of Quoting high-level innovative and entrepreneurial talent projects,Grant/Award Number:QCYRCXM-2022-135。
文摘Ionic conductive hydrogels(ICHs)prepared from natural bioresources are promising candidates for constructing flexible electronics for both commercialization and environmental sustainability due to their intrinsic characteristics.However,simultaneous realization of high stiffness,toughness,conductivity,and multifunctionality while ensuring processing simplicity is extremely challenging.Here,a poly(ionic liquid)(PIL)-macromolecule functionalization strategy within a NaOH/urea system is proposed to construct high-performance and versatile polysaccharide-based ICHs(e.g.,cellulosic ICHs).In this strategy,the elaborately designed“soft”(PIL chains)and“hard”(cellulose backbone)structures as well as the dynamic covalent and noncovalent bonds of the cross-linked networks endow the hydrogel with high mechanical strength(9.46±0.23 MPa compressive modulus),exceptional stretchability(214.3%),and toughness(3.64±0.12 MJ m^(−3)).Ingeniously,due to the inherent conductivity,design flexibility,and functional compatibility of the PILs,the hydrogels exhibit high conductivity(6.54±0.17 mS cm^(−1)),self-healing ability(94.5%±2.0%efficiency),antibacterial properties,freezing resistance,water retention,and recyclability.Interestingly,this strategy is extended to fabricate diverse hydrogels from various polysaccharides,including agar,alginate,hyaluronic acid,and guar gum.In addition,multimodal sensing(strain,temperature,and humidity)is realized based on the stimulus-responsive characteristics of the hydrogels.This strategy opens new perspectives for the design of biomass-based hydrogels and beyond.
