Copolymer microgels from mono- and disubstituted acrylamides: Phase behavior and hydrogen bonds
Copolymer microgels from mono- and disubstituted acrylamides: Phase behavior and hydrogen bonds
复制标题
DOI：
10.1021/ma800785w
复制
发表时间：
2008-09-23
期刊：
影响因子：
5.5
通讯作者：
Richtering, Walter
中科院分区：
文献类型：
--
作者：
Keerl, Martina;Smirnovas, Vytautas;Richtering, Walter
通过温度相关的光散射、傅里叶变换红外光谱和小角中子散射，证明了不同共聚物的微凝胶形态以及单体取代模式对其相变的影响。数据清楚地表明，相邻侧链形成分子内氢键的能力以及主链的柔韧性对相变温度有显著影响。由N - 异丙基丙烯酰胺（NIPAM）和N,N - 二乙基丙烯酰胺（DEAAM）或N - 异丙基甲基丙烯酰胺和DEAAM组成的共聚物微凝胶，由于DEAAM和单取代丙烯酰胺之间有利的氢键作用，其相变温度对组成呈非线性依赖关系。对于DEAAM - NIPAM共聚物，这导致相变温度降低到均聚物的相变温度以下。不同的微凝胶结构，即核 - 壳体系和无规共聚物微凝胶，证明了颗粒内单体单元的局部分布对相变位置的相关性。
The influence of microgel morphology and monomer Substitution pattern of different copolymers on their phase transition is demonstrated by temperature-dependent light scattering, Fourier transform infrared spectroscopy, and small-angle neutron scattering. The data clearly illustrate that the ability of the neighbored side chains to form intramolecular hydrogen bonds and the flexibility of the backbone influence the phase transition temperature significantly. Copolymer microgels consisting of N-isopropylacrylamide (NIPAM) and N,N-diethylacrylamide (DEAAM) or N-isopropylmethacrylamide and DEAAM show a nonlinear dependence of the phase transition temperature on composition due to favored hydrogen bonds between DEAAM and the monosubstituted acrylamide. In the case of DEAAM-NIPAM copolymers this leads to a depression of the transition temperature below that of the homopolymers. Different microgel architectures, namely core-shell systems and random copolymer microgels, demonstrate the relevance of the local distribution of the monomer units inside the particle on the location of the phase transition.