TY - JOUR
T1 - Chain extension as a strategy for the development of improved reverse thermo-responsive polymers
AU - Cohn, Daniel
AU - Sosnik, Alejandro
AU - Malal, Ram
AU - Zarka, Revital
AU - Garty, Shai
AU - Levy, Avi
PY - 2007/9
Y1 - 2007/9
N2 - The hypothesis that chain extension can be harnessed to the generation of improved reverse thermo-responsive polymers was tested by following two basic synthetic pathways: (1) the polymerization of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblocks using hexamethylene diisocyanate (HDI) as chain extender and (2) the covalent binding of poly(ethylene glycol) and poly(propylene glycol) chains, using phosgene as the connecting molecule. While in the former, the basic amphiphilic repeating unit is known for its own RTG behavior, the latter polymers consist of segments incapable of exhibiting a reverse thermal gelation (RTG) of their own. Dynamic light scattering (DLS) measurements revealed that the nanostructures formed by the chain extended polymers were markedly larger than those generated by PEO-PPO-PEO triblocks. While the size of Pluronic F127 micelles ranged from 15 to 20 nm, the higher molecular weight amphiphiles generated much larger nanostructures (20-400 nm). The chain extended polymers achieved much higher viscosities and their gels displayed enhanced long-term stability at 37°C.
AB - The hypothesis that chain extension can be harnessed to the generation of improved reverse thermo-responsive polymers was tested by following two basic synthetic pathways: (1) the polymerization of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblocks using hexamethylene diisocyanate (HDI) as chain extender and (2) the covalent binding of poly(ethylene glycol) and poly(propylene glycol) chains, using phosgene as the connecting molecule. While in the former, the basic amphiphilic repeating unit is known for its own RTG behavior, the latter polymers consist of segments incapable of exhibiting a reverse thermal gelation (RTG) of their own. Dynamic light scattering (DLS) measurements revealed that the nanostructures formed by the chain extended polymers were markedly larger than those generated by PEO-PPO-PEO triblocks. While the size of Pluronic F127 micelles ranged from 15 to 20 nm, the higher molecular weight amphiphiles generated much larger nanostructures (20-400 nm). The chain extended polymers achieved much higher viscosities and their gels displayed enhanced long-term stability at 37°C.
KW - Polymers
KW - Reverse thermo-responsiveness
KW - Rhelogical properties
UR - http://www.scopus.com/inward/record.url?scp=34648816812&partnerID=8YFLogxK
U2 - 10.1002/pat.961
DO - 10.1002/pat.961
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AN - SCOPUS:34648816812
SN - 1042-7147
VL - 18
SP - 731
EP - 736
JO - Polymers for Advanced Technologies
JF - Polymers for Advanced Technologies
IS - 9
ER -