文献类型：期刊文献

英文题名：Tuning the dynamic fragility of acrylic polymers by small molecules: the interplay of molecular structures

作者：Liu, Yuanbiao[1];Shi, Gaopeng[1];Wu, Guozhang[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai Key Lab Adv Polymer Mat, Shanghai 200237, Peoples R China

年份：2021

卷号：17

期号：32

起止页码：7541

外文期刊名：SOFT MATTER

收录：;EI(收录号：20213410807842);WOS:【SCI-EXPANDED(收录号:WOS:000679456300001)】；

基金：This research was supported by the National Natural Science Foundation of China (grant number 51873063 and 51373053).

语种：英文

外文关键词：Molecules - Glass transition - Phenols - Hydrogen bonds - Isomers

摘要：This report studied changes in the dynamic fragility (m) of poly(butyl methacrylate) (PBMA) by introducing guest hindered phenols capable of forming two or three intermolecular hydrogen bonds (inter-HBs) per molecule with the host polymer. The small molecules effectively decrease the m value, even if they apparently increase the glass transition temperature (T-g) of mixtures. The reduction in m was confirmed by enthalpy relaxation in two aspects: adding the guest molecule leads to a stronger cooling rate dependence of the limiting fictive temperature together with an apparent increase in aging rate of PBMA hybrids at low concentrations. By varying the molecule size and steric hindrance of the hydroxyl group on the hindered phenols, we clarified that m is primarily governed by the strength of inter-HB interactions, while the T-g value of mixtures depends on a combined effect of additive bulkiness and HB interaction. The anomalous dynamics was further rationalized not only by the HB-induced flexibility balance between side groups and backbone, but also by the reduction of cooperative rearranging sizes and alleviation of long-chain connectivity in such HB-driven hybrids.