The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution...The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.展开更多
Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular pro...Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular prostheses and stents,and the body’s reaction to artificial materials,could lead to chronic inflammation,a local increase in the concentration of proinflammatory factors,and stimulation of unwanted tissue growth.The introduction of nonsteroidal anti-inflammatory drugs into implantable devices could be used to obtain vascular implants that do not induce inflammation and do not induce neointimal tissue outgrowth.Methods:The scaffolds were made by electrospinning from mixtures of polyurethane(PU)with diclofenac(DF).The kinetics of DF release from the scaffolds composed of 3%PU/10%HSA/3%DMSO/DF and 3%PU/DF were studied.The biocompatibility and anti-inflammatory effects of the obtained scaffolds on human gingival fibroblasts and umbilical vein endothelial cells were studied.Results:Both types of scaffolds are characterized by fast DF release.The viability of cells cultured on scaffolds is 2 times worse than that of cells cultured on plastic.The level of the proinflammatory cytokine IL-6 in the culture medium of cells cultured on DF-containing scaffolds was lower than that of cells cultured on scaffolds without DF.Conclusion:The introduction of DF into scaffolds minimizes the inflammation caused by cell reactions to an artificial material.展开更多
Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea gran...Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.展开更多
Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Acco...Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.展开更多
To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crossli...To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC）, tensile mechanical tests and water contact angle （WCA） measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions （PBS） under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn＇t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.展开更多
Natural water absorbent konjac flour participates in synthesizing biodegraded and polyurethane foamed drape, which is used to release urea slowly.The experimental results indicate that the slowly-releasing velocity of...Natural water absorbent konjac flour participates in synthesizing biodegraded and polyurethane foamed drape, which is used to release urea slowly.The experimental results indicate that the slowly-releasing velocity of urea nitrogen and the degrading velocity of the drape can be controlled by regulating the thicknesses of drapes, the amount of konjac flour and the water content. In addition, the biodegradability of the drape was investigated by burying the specimens in earth afterwards,and results show this drape can be degraded naturally.展开更多
Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU p...Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.展开更多
Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, ...Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, dynamic mechanical properties and chemicals resistance of the resulting composites are investigated by FTIR, TEM, TGA, UV-Vis, DMA and chemicals soakage measurements. Results show that polyurethane molecules and silica nanoparticles are linked with covalent bonds. As a result, physical properties of polyurethane composites, such as thermal stability, surface hardness, weather and chemicals resistance are all improved when an appropriate concentration of silica nanoparticles are incorporated.展开更多
Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and br...Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and branched trimethylolpropane mono allyl ether（TMPAE）, are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes（TPUs）. In TPUs, the biodegradable polycaprolactone（PCL, M_n of 2000） is used as soft segment while 1,6-diisocyanatohexane（HDI） and chain extenders are used as hard segment. Fourier transform infrared spectroscopy（FTIR）, proton nuclear magnetic resonance spectroscppy（~1 H-NMR）, gel permeation chromatography（GPC）, differential scanning calorimetry（DSC）, dynamic mechanical analysis（DMA） and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio（R）, which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes.展开更多
A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segmen...A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segments, a new phoshporycholine, 2-（2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-（2-hydroxyethoxy）decyloxy） ethyl phosphorycholine （HDFOPC） as end-capper, and four polydiols, poly（tetramethylene glycol）s （PTMG）, polydimethylsiloxane （PDMS）, poly（1,6-hexyl-1,5-pentylcarbonate） （PHPC） and poly（propylene glycol） （PPG） as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.展开更多
A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained b...A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained by chain-extending of PCLA and polytetramethylene ether （PTMEG） with hexamethylene diisocyanate （HDI）. All the PCLAUs exhibit good shape memory properties with high shape fixity ratios above 98% and shape recovery ratios above 82% in the first cycle and 91% in the second cycle. PCLAUs with less CL content show faster recovery speed and PCLAUs with more CL content show higher shape recovery ratio. The trigger temperature can be tuned or controlled around body temperature by adjusting the molar ratio of LA to CL. The PCLAUs have potential applications in implant biomedical devices, especially for minimally invasive deployable devices.展开更多
Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by ...Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.展开更多
A series of fluorescent siloxane-polyurethanes（HPMS-PUs） containing an amino-functionalized,1 8-naphthalimide,fluorescent monomer（AABD） as a chain extender were synthesized.The properties of the HPMS-PUs were inve...A series of fluorescent siloxane-polyurethanes（HPMS-PUs） containing an amino-functionalized,1 8-naphthalimide,fluorescent monomer（AABD） as a chain extender were synthesized.The properties of the HPMS-PUs were investigated by UV–vis and fluorescence spectroscopies,thermogravimetric analysis and thermal migration behavior.The maximum absorption and emission wavelengths of HPMS-PUs showed a red shift of about 4 nm and a blue shift of about 9 nm,respectively,compared to those of AABD.The Stokes shifts of AABD and HPMS-PU2 were 3514 and 2931 cm 1,respectively.The quantum yield of HPMS-PU2 was 0.79,which was six times higher than that of AABD.Concentration self-quenching was observed in both AABD and HPMS-PUs.The fluorescence of HPMS-PUs was quite stable with respect to both temperature and fluorescence quencher effects.The thermal stability of HPMS-PUs increased with AABD content.The fluorophore units in the HPMS-PUs did not readily migrate.展开更多
The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted ...The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.展开更多
The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies ...The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies made with hydrolyzable and condensed tannins,but takes advantage of the higher number of hydroxyl groups present in lignin and their different aliphatic and aromatic character.The obtained materials were analyzed by Fourier transform infrared(FTIR)spectroscopy,matrix-assisted laser desorption ionization time-of-flight(MALDI-TOF)mass spectrometry and solid-state cross-polarization/magic angle spinning(CP MAS)13C nuclear magnetic resonance(NMR),which have revealed the presence of urethane functions.The interpretation of the results has shown a larger number of species than when tannins were used and has indicated the presence of two types of bonds in the new molecules formed:ionic and covalent bonds.展开更多
Polyoxetanes bearing short fluorinated and/or bromomethyl pendant groups were prepared from 3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane and/or 3,3-bisbromomethyloxetane by ring-opening polymerization.A series of novel...Polyoxetanes bearing short fluorinated and/or bromomethyl pendant groups were prepared from 3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane and/or 3,3-bisbromomethyloxetane by ring-opening polymerization.A series of novel polyurethanes(PUs)containing polyoxetanes as soft blocks was synthesized by the reaction of polyoxetanes,isophorone diisocyanate(IPDI),and 1,4-butanediol(BD).The thermal properties and wetting behavior of these novel polymers were evaluated using TGA,DSC and contact angle analysis.The cotton fabrics treated with PU3 showed good hydrophobic property,and its contact angle for water was 133°.展开更多
A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate wi...A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.展开更多
1,2-Dioxetane is a well-known chemiluminescent mechanophore allowing real-time monitoring of polymer chain scission,but usually suffers from fluorescence quenching in polar environments.Herein,a series of mechanochemi...1,2-Dioxetane is a well-known chemiluminescent mechanophore allowing real-time monitoring of polymer chain scission,but usually suffers from fluorescence quenching in polar environments.Herein,a series of mechanochemiluminescent waterborne polyurethanes/carbon dots composites(WPU-CDs)have been synthesized by incorporating fluorescent CDs to promote the energy transfer process in different environments.The resulting bulk WPUs,and in particular,their swollen films filled with a large amount of polar solvents(water and ionic liquid)emit intense mechanochemiluminescence.Thus force-induced covalent bond scission and stress distribution within these different WPU-CDs films can be sensitively visualized.Furthermore,the ionic liquid containing films exhibited both electrical and luminescent signal changes under stretching,which offer a new kind of force sensor responsive at a broad detecting strain range and for multi-mode strain analysis.This study is expected to stimulate new research endeavors in mechanistic insight on waterborne polyurethanes and the corresponding stretchable sensing devices.展开更多
Soy-protein isolate(SPI)was used to prepare non-isocyanate polyurethane(NIPU)thermosetting adhesives for wood panels by reacting it with dimethyl carbonate(DMC)and hexamethylene diamine.Both linear as well as branched...Soy-protein isolate(SPI)was used to prepare non-isocyanate polyurethane(NIPU)thermosetting adhesives for wood panels by reacting it with dimethyl carbonate(DMC)and hexamethylene diamine.Both linear as well as branched oligomers were obtained and identified,indicating how such oligomer structures could further cross-link to form a hardened network.Unusual structures were observed,namely carbamic acid-derived urethane linkages coupled with lactam structures.The curing of the adhesive was followed by thermomechanical analysis(TMA).It appeared to follow a two stages process:First,at a lower temperature(maximum 130℃),the growth of linear oligomers occurred,finally forming a physically entangled network.This appeared to collapse and disentangle,causing a decrease of MOE,as the temperature increases.This appears to be due to the ever more marked Brownian movements of the linear oligomer chains with the increase of the temperature.Second,chemical cross-linking of the chains appeared to ensue,forming a hardened network.This was shown by the thermomechanical analysis(TMA)showing two distinct MOE maxima peaks,one around 130℃ and the other around 220℃,with a very marked MOE decrease between the two.Plywood panels were prepared and bonded with the SPI-NIPU wood adhesive and the results obtained are presented.The adhesive appeared to pass comfortably the requirements for dry strength of relevant standards,showing to be suitable for interior grade plywood panels.It did not pass the requirements for wet tests.However,addition of 15%of glycerol diglycidyl ether improved the wet tests results but still not enough to satisfy the standards requirements.展开更多
Biodegradable porous polyurethanes scaffold have themselves opportunities in service, in-cluding controlled degradation rate, no-toxic degradation products. However, polyurethanes are lack of bioactive groups, which l...Biodegradable porous polyurethanes scaffold have themselves opportunities in service, in-cluding controlled degradation rate, no-toxic degradation products. However, polyurethanes are lack of bioactive groups, which limits their application. This review gives the common modification methods, surface functionalization and blending modification. In finally, the review puts forward to the bulk modification as a new method to enhance the bioactivity of polyure-thanes.展开更多
基金financially supported by the Maoming Science and Technology Bureau(No.2022DZXHT007)。
文摘The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.
基金supported by the Russian state-funded project for ICBFM SB RAS(grant number 125012300656-5)。
文摘Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular prostheses and stents,and the body’s reaction to artificial materials,could lead to chronic inflammation,a local increase in the concentration of proinflammatory factors,and stimulation of unwanted tissue growth.The introduction of nonsteroidal anti-inflammatory drugs into implantable devices could be used to obtain vascular implants that do not induce inflammation and do not induce neointimal tissue outgrowth.Methods:The scaffolds were made by electrospinning from mixtures of polyurethane(PU)with diclofenac(DF).The kinetics of DF release from the scaffolds composed of 3%PU/10%HSA/3%DMSO/DF and 3%PU/DF were studied.The biocompatibility and anti-inflammatory effects of the obtained scaffolds on human gingival fibroblasts and umbilical vein endothelial cells were studied.Results:Both types of scaffolds are characterized by fast DF release.The viability of cells cultured on scaffolds is 2 times worse than that of cells cultured on plastic.The level of the proinflammatory cytokine IL-6 in the culture medium of cells cultured on DF-containing scaffolds was lower than that of cells cultured on scaffolds without DF.Conclusion:The introduction of DF into scaffolds minimizes the inflammation caused by cell reactions to an artificial material.
基金the National Key Technology R&D Program of the 11th Five-Year Period (No.2006BAD10B08)
文摘Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.
基金financially supported by the National Natural Science Foundation of China(Nos.51333008,51273214 and 51073176)the project of key technological breakthrough for emerging industries of strategic importance(Nos.2011A091102001,and 2011A091102003)+2 种基金the Science and Technology Program of Guangdong Province(Nos.2010B010800021 and 2010A011300004)the Basic Scientific Research Foundation in Colleges and Universities of Ministry of Education of China(No.12lgjc08)the ST project of Hongyun Honghe Tobacco Group(No.HYHH2013YL06)
文摘Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.
基金supported by the National Natural Science Foundation of China(Nos.51073104 and 51173118)the Changjiang Scholars and Innovative Research Teams in Universities(No.IRT1163)the Sichuan Provincial Science Fund for Distinguished Young Scholars(No.09ZQ026-024)
文摘To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC）, tensile mechanical tests and water contact angle （WCA） measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions （PBS） under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn＇t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.
文摘Natural water absorbent konjac flour participates in synthesizing biodegraded and polyurethane foamed drape, which is used to release urea slowly.The experimental results indicate that the slowly-releasing velocity of urea nitrogen and the degrading velocity of the drape can be controlled by regulating the thicknesses of drapes, the amount of konjac flour and the water content. In addition, the biodegradability of the drape was investigated by burying the specimens in earth afterwards,and results show this drape can be degraded naturally.
基金supported by the National Natural Science Foundation of China(No.20874040)Research Funds from University of Jinan(XKY0721)
文摘Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.
基金supported by the Open Fund of Key Laboratory of Road & Bridge and Underground Engineering of Gansu Province(No.Kfjj-10-05)"Qing Lan" Talent Engineering Funds by Lanzhou Jiaotong University(No.QL-08- 03A)
文摘Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, dynamic mechanical properties and chemicals resistance of the resulting composites are investigated by FTIR, TEM, TGA, UV-Vis, DMA and chemicals soakage measurements. Results show that polyurethane molecules and silica nanoparticles are linked with covalent bonds. As a result, physical properties of polyurethane composites, such as thermal stability, surface hardness, weather and chemicals resistance are all improved when an appropriate concentration of silica nanoparticles are incorporated.
基金financially supported by the National Natural Science Foundation of China (No. 51573114)the National Science Fund for Distinguished Young Scholars of China (No. 51425305)the Project of State Key Laboratory of Polymer Materials Engineering (Sichuan University) (No. SKLPME 2016-2-04)
文摘Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and branched trimethylolpropane mono allyl ether（TMPAE）, are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes（TPUs）. In TPUs, the biodegradable polycaprolactone（PCL, M_n of 2000） is used as soft segment while 1,6-diisocyanatohexane（HDI） and chain extenders are used as hard segment. Fourier transform infrared spectroscopy（FTIR）, proton nuclear magnetic resonance spectroscppy（~1 H-NMR）, gel permeation chromatography（GPC）, differential scanning calorimetry（DSC）, dynamic mechanical analysis（DMA） and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio（R）, which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes.
基金financially supported by the National Natural Science Foundation of China(No.50673063)Program for the New-Century Excellent Talents of Ministry of Education of China(NCET-08-0381)Sichuan Provincial Science Fund for Distinguished Young Scholars(09ZQ026-024)
文摘A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segments, a new phoshporycholine, 2-（2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-（2-hydroxyethoxy）decyloxy） ethyl phosphorycholine （HDFOPC） as end-capper, and four polydiols, poly（tetramethylene glycol）s （PTMG）, polydimethylsiloxane （PDMS）, poly（1,6-hexyl-1,5-pentylcarbonate） （PHPC） and poly（propylene glycol） （PPG） as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.
基金financially supported by the National Key Technology R&D Program(No.2012BAI17B05)
文摘A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained by chain-extending of PCLA and polytetramethylene ether （PTMEG） with hexamethylene diisocyanate （HDI）. All the PCLAUs exhibit good shape memory properties with high shape fixity ratios above 98% and shape recovery ratios above 82% in the first cycle and 91% in the second cycle. PCLAUs with less CL content show faster recovery speed and PCLAUs with more CL content show higher shape recovery ratio. The trigger temperature can be tuned or controlled around body temperature by adjusting the molar ratio of LA to CL. The PCLAUs have potential applications in implant biomedical devices, especially for minimally invasive deployable devices.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFB0309300)the National Natural Science Foundation of China (No. 51773218)+1 种基金Youth Innovation Promotion Association of CAS (No. 2018338)Ningbo Natural Science Foundation (No.2018A610109)
文摘Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.
基金Financial support from the 863 program (No. 2011AA02A204)
文摘A series of fluorescent siloxane-polyurethanes（HPMS-PUs） containing an amino-functionalized,1 8-naphthalimide,fluorescent monomer（AABD） as a chain extender were synthesized.The properties of the HPMS-PUs were investigated by UV–vis and fluorescence spectroscopies,thermogravimetric analysis and thermal migration behavior.The maximum absorption and emission wavelengths of HPMS-PUs showed a red shift of about 4 nm and a blue shift of about 9 nm,respectively,compared to those of AABD.The Stokes shifts of AABD and HPMS-PU2 were 3514 and 2931 cm 1,respectively.The quantum yield of HPMS-PU2 was 0.79,which was six times higher than that of AABD.Concentration self-quenching was observed in both AABD and HPMS-PUs.The fluorescence of HPMS-PUs was quite stable with respect to both temperature and fluorescence quencher effects.The thermal stability of HPMS-PUs increased with AABD content.The fluorophore units in the HPMS-PUs did not readily migrate.
基金the Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET,Argentina)(PIP 20170100677)the Fondo para la Investigación Científica y Tecnológica(FONCYT)(PICT-2017-1318)the Universidad Nacional de Mar del Plata(UNMdP,15/G557,ING561/19)and to the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires(CIC)and the Universidad Tecnológica Nacional(UTN)for their financial support.
文摘The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.
文摘The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies made with hydrolyzable and condensed tannins,but takes advantage of the higher number of hydroxyl groups present in lignin and their different aliphatic and aromatic character.The obtained materials were analyzed by Fourier transform infrared(FTIR)spectroscopy,matrix-assisted laser desorption ionization time-of-flight(MALDI-TOF)mass spectrometry and solid-state cross-polarization/magic angle spinning(CP MAS)13C nuclear magnetic resonance(NMR),which have revealed the presence of urethane functions.The interpretation of the results has shown a larger number of species than when tannins were used and has indicated the presence of two types of bonds in the new molecules formed:ionic and covalent bonds.
基金Program for Changjiang Scholars and Innovative Research Teamin University,China(No.IRT0526)Shanghai Municipal Scientific Committee,China(No.08JC1400400)
文摘Polyoxetanes bearing short fluorinated and/or bromomethyl pendant groups were prepared from 3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane and/or 3,3-bisbromomethyloxetane by ring-opening polymerization.A series of novel polyurethanes(PUs)containing polyoxetanes as soft blocks was synthesized by the reaction of polyoxetanes,isophorone diisocyanate(IPDI),and 1,4-butanediol(BD).The thermal properties and wetting behavior of these novel polymers were evaluated using TGA,DSC and contact angle analysis.The cotton fabrics treated with PU3 showed good hydrophobic property,and its contact angle for water was 133°.
基金Funded by the National Natural Science Foundation of China(Nos.21244006 and 50873013)the Beijing Natural Science Foundation(No.2182056)
文摘A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.
基金financially supported by the National Natural Science Foundation of China(Nos.21905200,21975178 and 21734006)China Postdoctoral Science Foundation(No.2019M661006)。
文摘1,2-Dioxetane is a well-known chemiluminescent mechanophore allowing real-time monitoring of polymer chain scission,but usually suffers from fluorescence quenching in polar environments.Herein,a series of mechanochemiluminescent waterborne polyurethanes/carbon dots composites(WPU-CDs)have been synthesized by incorporating fluorescent CDs to promote the energy transfer process in different environments.The resulting bulk WPUs,and in particular,their swollen films filled with a large amount of polar solvents(water and ionic liquid)emit intense mechanochemiluminescence.Thus force-induced covalent bond scission and stress distribution within these different WPU-CDs films can be sensitively visualized.Furthermore,the ionic liquid containing films exhibited both electrical and luminescent signal changes under stretching,which offer a new kind of force sensor responsive at a broad detecting strain range and for multi-mode strain analysis.This study is expected to stimulate new research endeavors in mechanistic insight on waterborne polyurethanes and the corresponding stretchable sensing devices.
文摘Soy-protein isolate(SPI)was used to prepare non-isocyanate polyurethane(NIPU)thermosetting adhesives for wood panels by reacting it with dimethyl carbonate(DMC)and hexamethylene diamine.Both linear as well as branched oligomers were obtained and identified,indicating how such oligomer structures could further cross-link to form a hardened network.Unusual structures were observed,namely carbamic acid-derived urethane linkages coupled with lactam structures.The curing of the adhesive was followed by thermomechanical analysis(TMA).It appeared to follow a two stages process:First,at a lower temperature(maximum 130℃),the growth of linear oligomers occurred,finally forming a physically entangled network.This appeared to collapse and disentangle,causing a decrease of MOE,as the temperature increases.This appears to be due to the ever more marked Brownian movements of the linear oligomer chains with the increase of the temperature.Second,chemical cross-linking of the chains appeared to ensue,forming a hardened network.This was shown by the thermomechanical analysis(TMA)showing two distinct MOE maxima peaks,one around 130℃ and the other around 220℃,with a very marked MOE decrease between the two.Plywood panels were prepared and bonded with the SPI-NIPU wood adhesive and the results obtained are presented.The adhesive appeared to pass comfortably the requirements for dry strength of relevant standards,showing to be suitable for interior grade plywood panels.It did not pass the requirements for wet tests.However,addition of 15%of glycerol diglycidyl ether improved the wet tests results but still not enough to satisfy the standards requirements.
文摘Biodegradable porous polyurethanes scaffold have themselves opportunities in service, in-cluding controlled degradation rate, no-toxic degradation products. However, polyurethanes are lack of bioactive groups, which limits their application. This review gives the common modification methods, surface functionalization and blending modification. In finally, the review puts forward to the bulk modification as a new method to enhance the bioactivity of polyure-thanes.
