Temperature-responsive polymers have garnered significant attention due to their ability to respond to external stimuli.In this work,dual temperature-responsive block copolymers are synthesized via reversible addition...Temperature-responsive polymers have garnered significant attention due to their ability to respond to external stimuli.In this work,dual temperature-responsive block copolymers are synthesized via reversible addition-fragmentation chain transfer polymerization(RAFT)polymerization utilizing zwitterionic monomer methacryloyl ethyl sulfobetaine(SBMA) and N-isopropyl acrylamide(NIPAAm) as monomers.The thermal responsive behaviors can be easily modulated by incorporating additional hydrophobic monomer benzyl acrylate(BN) or hydrophilic monomer acrylic acid(AA),adjusting concentration or pH,or varying the degree of polymerization of the block chain segments.The cloud points of the copolymers are determined by UV-Vis spectrophotometry,and these copolymers exhibit both controlled upper and lower critical solu bility temperatures(LCST and UCST) in aqueous solution.This study analyzes and summarizes the influencing factors of dual temperature responsive block copolymers by exploring the effects of various conditions on the phase transition temperature of temperature-sensitive polymers to explore the relationship between their properties and environment and structure to make them more selective in terms of temperature application range and regulation laws.It is very interesting that the introduction of poly-acrylic acid(PAA) segments in the middle of di-block copolymer PSBMA_(55)-b-PNIPAAm_(80) to form PSBMA_(55)-b-PAA_(x)-b-PNIPAAm_(80) results in a reversal of temperature-responsive behaviors from 'U'(LCST UCST) type,while the copolymer PSBMA_(55)-b-P(NIPAAm_(80)-co-AA_(x)) not.This work provides a clue for tuning the phase transition behavior of polymers for manufacture of extreme smart materials.展开更多
Temperature sensitive poly(N vinylcaprolactam) was prepared by γ radiation polymerization.The effects of radiation dosage,radiation dose rate and monomer concentration on polymerization and the LCST characterisitcs o...Temperature sensitive poly(N vinylcaprolactam) was prepared by γ radiation polymerization.The effects of radiation dosage,radiation dose rate and monomer concentration on polymerization and the LCST characterisitcs of the polymer were studied.The results show that the polymer thus obtained has good temperature sensitivity and uniformity within certain radiation dosage range(1.4～4kGy) and dose rate range (2～14Gy/min).展开更多
In this study,hydrogels of P(NIPA-co-NVP)/clay were synthesized byγ-ray radiation.Different thermo-sensitive hydrogels were made under different experimental conditions such as dose,monomer ratio,and con- tent of cla...In this study,hydrogels of P(NIPA-co-NVP)/clay were synthesized byγ-ray radiation.Different thermo-sensitive hydrogels were made under different experimental conditions such as dose,monomer ratio,and con- tent of clay.X-ray diffraction shows that the layer distance between Na-clays is changed from 1.6 to 2.7 nm because Na-clay pieces can be intercalated or exfoliated by HTMAB,and that between P(NIPA-co-NVP)/clay pieces is 3.4 nm. The swelling property tests show that the LCST of P(NIPA-co-NVP) is higher than PNIPA.With the increase of NVP content,LCST is higher.As the ratio of NIPA/NVP is 95/5,hydrogel shows the best swelling property and LCST is 37℃.LCST of P(NIPA-co-NVP)/clay hydrogel is not changed,but the strength and swelling properties are better.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 22271207)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。
文摘Temperature-responsive polymers have garnered significant attention due to their ability to respond to external stimuli.In this work,dual temperature-responsive block copolymers are synthesized via reversible addition-fragmentation chain transfer polymerization(RAFT)polymerization utilizing zwitterionic monomer methacryloyl ethyl sulfobetaine(SBMA) and N-isopropyl acrylamide(NIPAAm) as monomers.The thermal responsive behaviors can be easily modulated by incorporating additional hydrophobic monomer benzyl acrylate(BN) or hydrophilic monomer acrylic acid(AA),adjusting concentration or pH,or varying the degree of polymerization of the block chain segments.The cloud points of the copolymers are determined by UV-Vis spectrophotometry,and these copolymers exhibit both controlled upper and lower critical solu bility temperatures(LCST and UCST) in aqueous solution.This study analyzes and summarizes the influencing factors of dual temperature responsive block copolymers by exploring the effects of various conditions on the phase transition temperature of temperature-sensitive polymers to explore the relationship between their properties and environment and structure to make them more selective in terms of temperature application range and regulation laws.It is very interesting that the introduction of poly-acrylic acid(PAA) segments in the middle of di-block copolymer PSBMA_(55)-b-PNIPAAm_(80) to form PSBMA_(55)-b-PAA_(x)-b-PNIPAAm_(80) results in a reversal of temperature-responsive behaviors from 'U'(LCST UCST) type,while the copolymer PSBMA_(55)-b-P(NIPAAm_(80)-co-AA_(x)) not.This work provides a clue for tuning the phase transition behavior of polymers for manufacture of extreme smart materials.
文摘Temperature sensitive poly(N vinylcaprolactam) was prepared by γ radiation polymerization.The effects of radiation dosage,radiation dose rate and monomer concentration on polymerization and the LCST characterisitcs of the polymer were studied.The results show that the polymer thus obtained has good temperature sensitivity and uniformity within certain radiation dosage range(1.4～4kGy) and dose rate range (2～14Gy/min).
基金Supported by Natural Science Foundation of Henan Province,China(0611023900)
文摘In this study,hydrogels of P(NIPA-co-NVP)/clay were synthesized byγ-ray radiation.Different thermo-sensitive hydrogels were made under different experimental conditions such as dose,monomer ratio,and con- tent of clay.X-ray diffraction shows that the layer distance between Na-clays is changed from 1.6 to 2.7 nm because Na-clay pieces can be intercalated or exfoliated by HTMAB,and that between P(NIPA-co-NVP)/clay pieces is 3.4 nm. The swelling property tests show that the LCST of P(NIPA-co-NVP) is higher than PNIPA.With the increase of NVP content,LCST is higher.As the ratio of NIPA/NVP is 95/5,hydrogel shows the best swelling property and LCST is 37℃.LCST of P(NIPA-co-NVP)/clay hydrogel is not changed,but the strength and swelling properties are better.
