TY - JOUR
T1 - Reverse thermo-responsive poly(ethylene oxide) and poly(propylene oxide) multiblock copolymers
AU - Sosnik, Alejandro
AU - Cohn, Daniel
PY - 2005/2
Y1 - 2005/2
N2 - Aiming at developing new reverse thermo-responsive polymers, poly(ethylene oxide)-poly(propylene oxide) multiblock copolymers were synthesized by covalently binding the two components using carbonyl chloride and diacyl chlorides as the coupling molecules. The appropriate selection of the various components allowed the generation of systems displaying much enhanced rheological properties. For example, 15wt% aqueous solutions of an alternating poly(ether-carbonate) comprising PEO6000 and PPO3000 segments, achieved a viscosity of 140,000Pas, while the commercially available Pluronic F127 displayed 5,000Pas only. Furthermore, the structure of the chain extender played a key role in determining the sol-gel transition. While poly(ether-ester)s containing therephtaloyl (para) and isophtaloyl (metha) coupling units failed to gel at any concentration, a 15wt% aqueous solution of the polymer chain-extended with phtaloyl chloride (ortho) gelled at 43°C. The water solutions were also studied by dynamic light scattering and a clear influence of the PEO/PPO ratio on the aggregate size was observed. By incorporating short aliphatic oligoesters into the backbone, prior to the chain extension stage, reverse thermal gelation-displaying biodegradable poly(ether-ester-carbonate)s, were generated.
AB - Aiming at developing new reverse thermo-responsive polymers, poly(ethylene oxide)-poly(propylene oxide) multiblock copolymers were synthesized by covalently binding the two components using carbonyl chloride and diacyl chlorides as the coupling molecules. The appropriate selection of the various components allowed the generation of systems displaying much enhanced rheological properties. For example, 15wt% aqueous solutions of an alternating poly(ether-carbonate) comprising PEO6000 and PPO3000 segments, achieved a viscosity of 140,000Pas, while the commercially available Pluronic F127 displayed 5,000Pas only. Furthermore, the structure of the chain extender played a key role in determining the sol-gel transition. While poly(ether-ester)s containing therephtaloyl (para) and isophtaloyl (metha) coupling units failed to gel at any concentration, a 15wt% aqueous solution of the polymer chain-extended with phtaloyl chloride (ortho) gelled at 43°C. The water solutions were also studied by dynamic light scattering and a clear influence of the PEO/PPO ratio on the aggregate size was observed. By incorporating short aliphatic oligoesters into the backbone, prior to the chain extension stage, reverse thermal gelation-displaying biodegradable poly(ether-ester-carbonate)s, were generated.
KW - (PEO-PPO) multiblock copolymers
KW - Poly(ether carbonate)s
KW - Poly(ether ester)s
KW - Reverse thermo-responsive systems
KW - Viscosity vs. temperature profile
UR - http://www.scopus.com/inward/record.url?scp=3242668912&partnerID=8YFLogxK
U2 - 10.1016/j.biomaterials.2004.02.041
DO - 10.1016/j.biomaterials.2004.02.041
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C2 - 15275809
AN - SCOPUS:3242668912
SN - 0142-9612
VL - 26
SP - 349
EP - 357
JO - Biomaterials
JF - Biomaterials
IS - 4
ER -