Small-angle neutron scattering study on microstructure of poly(N-isopropylacrylamide)-block-poly(ethylene glycol) in water

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• 作者：Motokawa ; Ryuhei ; Annaka ; Masahiko ; Nakahira ; Takayuki ; Koizumi ; Satoshi
• 关键词：Block copolymer ; Gel ; Poly(N-isopropylacrylamide) ; Microphase separation ; Small-angle neutron scattering
• 刊名：Colloids and Surfaces B ; Biointerfaces
• 出版年：2004
• 期刊代码：14_09277765
• 类别：ms
• 出版时间：November 15, 2004
• 卷：38
• 期：3-4
• 页码：213-219
• 文件大小：276 K

摘要

By employing small-angle neutron scattering (SANS), we investigated the microstructures of, poly(N-isopropylacrylamide) (PNIPA)-block-poly(ethylene glycol) (PEG) (NE) in deuterated water D₂O, as related to macroscopic behaviors of fluidity, turbidity and synerisis. SANS revealed following results: (i) microphase separation occurs at around above 17°C in a temperature range of transparent sol below 30°C. In the microdomain appeared in the transparent sol state, both block chains of PNIPA and PEG are swollen by water; (ii) for the NE solution of polymer concentration W_p > 3.5%(w/v), corresponding to opaque gel above 30°C, a percolated structure, i.e., network-like domain is formed by NE as a result of macrophase separation due to dehydration of the PNIPA chains. As the temperature increases toward 40°C, the network domain is squeezed along a direction parallel to the NE interface, which leads to increase of the interfacial thickness given by swollen PEG chains and to the macroscopic synerisis behavior.