The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiati...The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiation polymerization using Co^60 γ-ray. Their swelling equilibrium data in the media of deionized water, NaCl aqueous solutions and different pH buffer solutions are determined. It appears that lower critical solution temperature （LCST） of the hydrogels will drop with the increase of ionic strength and increase with the rising of acrylamide content, A semi-empirical formula is set up with the experimental results. Moreover, it also indicates that this copolymer is pH-sensitive, which is similar to the homopolymer of PNIPAAm.展开更多
Acrylonitrile/N-[4-（aminosulfonyl）phenyl]acrylamide （AN/ASPAA） copolymers were synthesized and used as a host of lithium ion conducting electrolytes. The composition, molecular weight and molecular weight distribu...Acrylonitrile/N-[4-（aminosulfonyl）phenyl]acrylamide （AN/ASPAA） copolymers were synthesized and used as a host of lithium ion conducting electrolytes. The composition, molecular weight and molecular weight distribution of AN/ASPAA copolymers were determined, and the influence of copolymer composition on the glass temperature of AN/ASPAA copolymers and the ion conductivity of electrolytes were investigated. The molecular weights of AN/ASPAA copolymers were lower than those of AN and ASPAA homopolymers due to the cross-termination reaction. The glass temperatures of AN/ASPAA copolymers increased as the molar fraction of ASPAA units in copolymers increased. The lithium ion conductivities of the polymer electrolytes increased initially as the molar fraction of ASPAA units in copolymers increased, and a maximum conductivity was achieved when the molar fraction of ASPAA in the copolymer was 16.8%.展开更多
Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution tempera...Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution temperature （LCST） has been investigated.展开更多
In this paper, the helix-sense-selective polymerization of N,N-diphenyl acrylamide (DPAA) and N,N-diphenyl methacrylamide(DPMAA) were studied with living helix prepolymer as anionic initiator, and the chiral optical p...In this paper, the helix-sense-selective polymerization of N,N-diphenyl acrylamide (DPAA) and N,N-diphenyl methacrylamide(DPMAA) were studied with living helix prepolymer as anionic initiator, and the chiral optical properties of the obtained polymers were investigated too. It was shown that optically active polymers of DPAA and DPMAA could be obtained under the experimental condition, and exhibited the same screw sense as that of the prepolymer.展开更多
The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of tem...The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of temperature and pH in aqueous solutions. It was shown that controlled alteration of the hydrogel phase transition temperature can be achieved by changing their composition and pH of the environment. Increase in content of hydrophilic allylamine from 10 to 60 wt% in monomer mixture causes a shift of the phase transition temperature from 35oC to 47oC. Hydrogels with N-isopropylacrylamide/allylamine hydrochloride mass ratio of 3:2 show the highest pH-response. Values of average molecular weight between polymer cross-links, , and Flory parameter, χ, were calculated using temperature dependences of the equilibrium swelling of the synthesized hydrogel.展开更多
Homopolymerization of N-pyrimidinyl acrylamide (NPA) was reported for the first time. The polymer (polyNPA) was soluble only in acidic media and fluoroalcohols, and only in fluoroalcohol was homogeneous polymerization...Homopolymerization of N-pyrimidinyl acrylamide (NPA) was reported for the first time. The polymer (polyNPA) was soluble only in acidic media and fluoroalcohols, and only in fluoroalcohol was homogeneous polymerization of NPA feasible. 1H NMR analysis proved that a 1:1 H-bonding complex could be formed between NPA and α,α-bis(trifluoromethyl)phenyl propan-2-ol (BTMP). Cumyl dithiobenzoate mediated reversible addition-fragmentation chain transfer (RAFT) polymerization of NPA in BTMP was carried out. 1H NMR analyses proved that the molecular weight increased linearly with the monomer conversion. The polymer prepared in conventional solvents was atactic while in protic media the syndiotacticity was slightly enhanced.展开更多
Geometry optimization and subsequent harmonic vibration calculations of prior synthesized （E）-3-（4-fluorophenyl）-N-[4-（phenyl-amino） quinazoline-7-yl] acrylamide were carried out by DFT/B3LYP method with both 6-...Geometry optimization and subsequent harmonic vibration calculations of prior synthesized （E）-3-（4-fluorophenyl）-N-[4-（phenyl-amino） quinazoline-7-yl] acrylamide were carried out by DFT/B3LYP method with both 6-31G and 6-311G basis sets.The Infrared （IR） spectrum of the title compound was recorded in the field of 400-4000 cm 1 and then assigned.The correlation analyses between the scaled theoretical vibration frequencies and the experimental ones indicate that there exist good linearity relationships since the correlation coefficients R 2 are larger than 0.999.The intramolecular interactions existed in the title molecule were confirmed by the Atoms in molecules （AIM） method,and their influences on the absorption frequency were also investigated.展开更多
Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment we...Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment were prepared as follows. The precursor copolymer poly(Boc-LysAA-OtBu-b-PDMS) was obtained from radical polymerization of N-α-acrylamide-N-ε-tert-butoxycarbonyl-L-lysine-tert-butylester (Boc-LysAA-OtBu) initiated with 4,4’-azobis(polydimethylsiloxane 4-cyanopentanoate) (azo-PDMS) with the molecular weight of PDMS Mw = 4.3 × 103 in the presence of 2-mercaptoethanol (2-ME) as a chain-transfer agent. Removal of the protecting groups of the precursor copolymer was carried out in 80% trifluoroacetic acid aqueous solution to give poly(LysAA-b-DMS)-1-3. The weight average molecular weight of poly(LysAA-b-DMS)-1-3 was Mw = 1.02 × 104 – 2.52 × 104. From the 1H-NMR and fluorescence spectra measurements, poly(LysAA-b-DMS)-1-3 was determined to self-organize and form core-shell micelles in water. The critical micelle concentration (CMC) increased to 1000 - 4000 mg·L–1 with increasing molar ratio of the poly(LysAA) segment from 0.42 to 0.65. From morphological analysis with a scanning probe microscope (SPM), poly(LysAA-b-DMS) has microphase-separated structures made up of hydrophilic and hydrophobic regions with the domain size ranging from several tens to several hundreds of nanometers. Inhibition of thrombin activity of poly(LysAA-b-DMS) was evaluated from the Michaelis constant (KM) and catalytic activity (kcat) for the enzymatic reaction of thrombin and synthetic substrate S-2238 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.10 - 0.11 mM and 4.04 × 105 – 4.26 × 105 min–1, respectively. Fibrinolytic activity was also verified from the transformation of plasminogen to plasmin by tissue plasminogen activator (t-PA) using synthetic substrate S-2251 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.07 mM and 5.73 × 106 –5.95 × 106 min–1, respectively.展开更多
The purpose of this study is to examine the structure and the temperature-responsive anion exchange property of amino-functionalized mesoporous silica coated with temperature-responsive copolymer, poly(N-isopropylacry...The purpose of this study is to examine the structure and the temperature-responsive anion exchange property of amino-functionalized mesoporous silica coated with temperature-responsive copolymer, poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-co-Am)). For this purpose, the composites which contained 0, 10, or 20 wt% of Am were synthesized. From the TG results, it was found that the amounts of copolymer immobilized on the mesoporous silica were 1.6 - 2.6 wt%. XRD patterns revealed that the structures of composites were hexagonal and almost the same as that of original mesoporous silica without polymer. At low temperature the methyl orange (MO) anions adsorbed and desorbed reversibly with changing pH of the solution, while at high temperature the MO anions did not. This temperature, at which the amount of adsorbed MO anions changed considerably, shifted to the higher temperature side with increasing the amount of added Am.展开更多
Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（...Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（NIPAm） in dimethylsulfoxide（DMSO） in the presence of NaCMC. The structures of hydrogels were characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and differential scanning calorimetry（DSC）. SEM images show that the hydrogels present porous network structures. Most water in the hydrogels were free water and freezing water. The equilibrium swelling ratio（ESR） and swelling rate（SR） were quite different at various swelling temperature. ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃, that is to say, the hydrogels exhibited the good temperature sensitivity at about 33 ℃ similar to low critical solution temperature（LCST） of pure PNIPAm, swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism. Moreover, the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature, the equillibrium swelling ratio（ESR） and swelling rate of the hydrogels increased with increasing of NaCMC content, i e. It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels展开更多
Global energy issues and the reliance on hydrocarbon resources have resulted in the reduction of petroleum sources, and the focus of the chemical industries has shifted to substitute raw material sources. The major ra...Global energy issues and the reliance on hydrocarbon resources have resulted in the reduction of petroleum sources, and the focus of the chemical industries has shifted to substitute raw material sources. The major raw materials used in wood adhesives, such as hydrocarbons like polyvinyl acetate, would be gradually replaced by renewable natural polymers. Currently, polyvinyl alcohol has the limitation of petroleum origin, which is non-economical and it will be replaced by biopolymers. Conventionally available wood adhesive emulsions are colloid-like polyvinyl alcohol stabilized. Starch, being a naturally available polymer, has gained interest from researchers for replacing polyvinyl alcohol as a stabilizer. New research on sustainable, economical, biodegradable, renewable, and environmentally friendly starch grafted polyvinyl acetate emulsion that was synthesized by the graft polymerization of vinyl acetate monomer onto starch. However, starch grafted polyvinyl acetate emulsion-based adhesive’s properties, such as poor water resistance, weak adhesion, delayed drying rate and delayed setting speed, have resulted in limitations in its application as a wood adhesive. A detailed review of starch grafting on vinyl acetate and comonomers like acrylamides, and acrylic acid, and the addition of nano-fillers to enhance the water resistance and performance properties of sustainable adhesives has been explained.展开更多
基金Project Supported by Science Foundation of Shanghai MunicipalCommission of Science and Technology (Grant No .02DJ14030)
文摘The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiation polymerization using Co^60 γ-ray. Their swelling equilibrium data in the media of deionized water, NaCl aqueous solutions and different pH buffer solutions are determined. It appears that lower critical solution temperature （LCST） of the hydrogels will drop with the increase of ionic strength and increase with the rising of acrylamide content, A semi-empirical formula is set up with the experimental results. Moreover, it also indicates that this copolymer is pH-sensitive, which is similar to the homopolymer of PNIPAAm.
文摘Acrylonitrile/N-[4-（aminosulfonyl）phenyl]acrylamide （AN/ASPAA） copolymers were synthesized and used as a host of lithium ion conducting electrolytes. The composition, molecular weight and molecular weight distribution of AN/ASPAA copolymers were determined, and the influence of copolymer composition on the glass temperature of AN/ASPAA copolymers and the ion conductivity of electrolytes were investigated. The molecular weights of AN/ASPAA copolymers were lower than those of AN and ASPAA homopolymers due to the cross-termination reaction. The glass temperatures of AN/ASPAA copolymers increased as the molar fraction of ASPAA units in copolymers increased. The lithium ion conductivities of the polymer electrolytes increased initially as the molar fraction of ASPAA units in copolymers increased, and a maximum conductivity was achieved when the molar fraction of ASPAA in the copolymer was 16.8%.
文摘Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution temperature （LCST） has been investigated.
基金The authors are grateful to the National Natural Science Foundation of China for financial support.
文摘In this paper, the helix-sense-selective polymerization of N,N-diphenyl acrylamide (DPAA) and N,N-diphenyl methacrylamide(DPMAA) were studied with living helix prepolymer as anionic initiator, and the chiral optical properties of the obtained polymers were investigated too. It was shown that optically active polymers of DPAA and DPMAA could be obtained under the experimental condition, and exhibited the same screw sense as that of the prepolymer.
文摘The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of temperature and pH in aqueous solutions. It was shown that controlled alteration of the hydrogel phase transition temperature can be achieved by changing their composition and pH of the environment. Increase in content of hydrophilic allylamine from 10 to 60 wt% in monomer mixture causes a shift of the phase transition temperature from 35oC to 47oC. Hydrogels with N-isopropylacrylamide/allylamine hydrochloride mass ratio of 3:2 show the highest pH-response. Values of average molecular weight between polymer cross-links, , and Flory parameter, χ, were calculated using temperature dependences of the equilibrium swelling of the synthesized hydrogel.
文摘Homopolymerization of N-pyrimidinyl acrylamide (NPA) was reported for the first time. The polymer (polyNPA) was soluble only in acidic media and fluoroalcohols, and only in fluoroalcohol was homogeneous polymerization of NPA feasible. 1H NMR analysis proved that a 1:1 H-bonding complex could be formed between NPA and α,α-bis(trifluoromethyl)phenyl propan-2-ol (BTMP). Cumyl dithiobenzoate mediated reversible addition-fragmentation chain transfer (RAFT) polymerization of NPA in BTMP was carried out. 1H NMR analyses proved that the molecular weight increased linearly with the monomer conversion. The polymer prepared in conventional solvents was atactic while in protic media the syndiotacticity was slightly enhanced.
文摘Geometry optimization and subsequent harmonic vibration calculations of prior synthesized （E）-3-（4-fluorophenyl）-N-[4-（phenyl-amino） quinazoline-7-yl] acrylamide were carried out by DFT/B3LYP method with both 6-31G and 6-311G basis sets.The Infrared （IR） spectrum of the title compound was recorded in the field of 400-4000 cm 1 and then assigned.The correlation analyses between the scaled theoretical vibration frequencies and the experimental ones indicate that there exist good linearity relationships since the correlation coefficients R 2 are larger than 0.999.The intramolecular interactions existed in the title molecule were confirmed by the Atoms in molecules （AIM） method,and their influences on the absorption frequency were also investigated.
文摘Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment were prepared as follows. The precursor copolymer poly(Boc-LysAA-OtBu-b-PDMS) was obtained from radical polymerization of N-α-acrylamide-N-ε-tert-butoxycarbonyl-L-lysine-tert-butylester (Boc-LysAA-OtBu) initiated with 4,4’-azobis(polydimethylsiloxane 4-cyanopentanoate) (azo-PDMS) with the molecular weight of PDMS Mw = 4.3 × 103 in the presence of 2-mercaptoethanol (2-ME) as a chain-transfer agent. Removal of the protecting groups of the precursor copolymer was carried out in 80% trifluoroacetic acid aqueous solution to give poly(LysAA-b-DMS)-1-3. The weight average molecular weight of poly(LysAA-b-DMS)-1-3 was Mw = 1.02 × 104 – 2.52 × 104. From the 1H-NMR and fluorescence spectra measurements, poly(LysAA-b-DMS)-1-3 was determined to self-organize and form core-shell micelles in water. The critical micelle concentration (CMC) increased to 1000 - 4000 mg·L–1 with increasing molar ratio of the poly(LysAA) segment from 0.42 to 0.65. From morphological analysis with a scanning probe microscope (SPM), poly(LysAA-b-DMS) has microphase-separated structures made up of hydrophilic and hydrophobic regions with the domain size ranging from several tens to several hundreds of nanometers. Inhibition of thrombin activity of poly(LysAA-b-DMS) was evaluated from the Michaelis constant (KM) and catalytic activity (kcat) for the enzymatic reaction of thrombin and synthetic substrate S-2238 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.10 - 0.11 mM and 4.04 × 105 – 4.26 × 105 min–1, respectively. Fibrinolytic activity was also verified from the transformation of plasminogen to plasmin by tissue plasminogen activator (t-PA) using synthetic substrate S-2251 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.07 mM and 5.73 × 106 –5.95 × 106 min–1, respectively.
文摘The purpose of this study is to examine the structure and the temperature-responsive anion exchange property of amino-functionalized mesoporous silica coated with temperature-responsive copolymer, poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-co-Am)). For this purpose, the composites which contained 0, 10, or 20 wt% of Am were synthesized. From the TG results, it was found that the amounts of copolymer immobilized on the mesoporous silica were 1.6 - 2.6 wt%. XRD patterns revealed that the structures of composites were hexagonal and almost the same as that of original mesoporous silica without polymer. At low temperature the methyl orange (MO) anions adsorbed and desorbed reversibly with changing pH of the solution, while at high temperature the MO anions did not. This temperature, at which the amount of adsorbed MO anions changed considerably, shifted to the higher temperature side with increasing the amount of added Am.
基金Funded by the National Natural Science Foundation of China(50973129)the Natural Science Found of Guangdong Province(07001781)+1 种基金the Open Project of Key Laboratory of Cellulose and Lignocellulosics ChemistryChinese Academy of Science(LCLC-2005-168)
文摘Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（NIPAm） in dimethylsulfoxide（DMSO） in the presence of NaCMC. The structures of hydrogels were characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and differential scanning calorimetry（DSC）. SEM images show that the hydrogels present porous network structures. Most water in the hydrogels were free water and freezing water. The equilibrium swelling ratio（ESR） and swelling rate（SR） were quite different at various swelling temperature. ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃, that is to say, the hydrogels exhibited the good temperature sensitivity at about 33 ℃ similar to low critical solution temperature（LCST） of pure PNIPAm, swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism. Moreover, the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature, the equillibrium swelling ratio（ESR） and swelling rate of the hydrogels increased with increasing of NaCMC content, i e. It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels
文摘Global energy issues and the reliance on hydrocarbon resources have resulted in the reduction of petroleum sources, and the focus of the chemical industries has shifted to substitute raw material sources. The major raw materials used in wood adhesives, such as hydrocarbons like polyvinyl acetate, would be gradually replaced by renewable natural polymers. Currently, polyvinyl alcohol has the limitation of petroleum origin, which is non-economical and it will be replaced by biopolymers. Conventionally available wood adhesive emulsions are colloid-like polyvinyl alcohol stabilized. Starch, being a naturally available polymer, has gained interest from researchers for replacing polyvinyl alcohol as a stabilizer. New research on sustainable, economical, biodegradable, renewable, and environmentally friendly starch grafted polyvinyl acetate emulsion that was synthesized by the graft polymerization of vinyl acetate monomer onto starch. However, starch grafted polyvinyl acetate emulsion-based adhesive’s properties, such as poor water resistance, weak adhesion, delayed drying rate and delayed setting speed, have resulted in limitations in its application as a wood adhesive. A detailed review of starch grafting on vinyl acetate and comonomers like acrylamides, and acrylic acid, and the addition of nano-fillers to enhance the water resistance and performance properties of sustainable adhesives has been explained.
