Self-Assembled Micelles from Thermoresponsive Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) Diblock Copolymers in Aqueous Solution
Self-Assembled Micelles from Thermoresponsive Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) Diblock Copolymers in Aqueous Solution
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DOI：
10.1021/acs.macromol.0c02189
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发表时间：
2021-01-12
期刊：
影响因子：
5.5
通讯作者：
Papadakis, Christine M.
中科院分区：
文献类型：
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作者：
Ko, Chia-Hsin;Henschel, Cristiane;Papadakis, Christine M.
研究了由短的永久疏水性聚甲基丙烯酸甲酯和长的热响应性聚N-异丙基丙烯酰胺制成的热响应性两亲性二嵌段共聚物PMMA(21)-b-PNIPAM(283)在水溶液中的温度依赖性相行为和自组装行为。比浊法、动态光散射 (DLS) 和同步加速器小角度 X 射线散射 (SAXS) 提供与温度相关的结构信息。在稀溶液中观察到较低的临界溶解温度 (LCST) 行为，浊点 T-CP = 31.1 摄氏度。在 T-CP 下面，存在球形核壳胶束，具有小的 PMMA 核和具有径向水含量梯度的水合 PNIPAM 壳。在 T-CP 以下，胶束相互渗透并表现出弱相关性。当温度接近 T-CP 时，胶束核收缩，因此聚集数减少，表明 PMMA 块仍然是可移动的。此外，胶束壳在To以上脱水，并且胶束显着收缩。它们形成团簇，当温度远高于 T-CP 时，团簇会生长并转变为大型致密聚集体。
The temperature-dependent phase behavior and self-assembly behavior in aqueous solution of the thermoresponsive amphiphilic diblock copolymer PMMA(21)-b-PNIPAM(283 )made of a short permanently hydrophobic poly(methyl methacrylate) block and a long thermoresponsive poly(N-isopropylacrylamide) are studied. Turbidimetry, dynamic light scattering (DLS), and synchrotron small-angle X-ray scattering (SAXS) provide temperature-dependent structure information. A lower critical solution temperature (LCST) behavior with a cloud point T-CP = 31.1 degrees C in dilute solution is observed. Below T-CP, spherical core-shell micelles are present, having a small PMMA core and a hydrated PNIPAM shell with a radial gradient of water content. Below T-CP, the micelles are interpenetrated and show a weak correlation with each other. As the temperature approaches T-CP, the micellar core shrinks and thus, the aggregation number decreases, revealing that the PMMA blocks are still mobile. Moreover, the micellar shell dehydrates above To, and the micelles notably contract. They form clusters, which grow and transform into large compact aggregates as temperature is raised far above T-CP.