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 Hydrogen Bonding Strength

作者：Liu, Chongyang[1];Liu, Zhiyuan[1];Yin, Xiaotong[1];Wu, Guozhang[1]

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

年份：2015

卷号：48

期号：12

起止页码：4196

外文期刊名：MACROMOLECULES

收录：;EI(收录号：20152600974216);WOS:【SCI-EXPANDED(收录号:WOS:000356988700045)】；

基金：This research was supported by grants from the "973" project (2013CB035505), the National Natural Science Foundation of China (51373053), and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：Fourier transform infrared spectroscopy - Glass transition - Hydrogen bonds - Spectrometers - Hydrogen - Molecules - Glass - Differential scanning calorimetry - Isomers

摘要：High-T-g polymers exhibit high fragilities in general. Here, we report for the first time that small molecules with double phenolic end groups are effective to independently mediate the dynamic fragility (m) and glass transition temperature (T-g) of acrylic polymers. Broad band dielectric spectrometer (BDS), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimeter (DSC) measurements showed that the addition of small molecules with a concentration lower than 30 wt % leads to a narrower relaxation time distribution of the intermolecular cooperative rearrangement motion because of the formation of hydrogen bonding networks. These acrylic polymers exhibited a significant decrease in m while showing a linear increase in T-g by changing the loading of the small molecules. Further experimental results demonstrated, that m decreases, monotonically with intermolecular hydrogen bonding strength for a given host polymer matrix. The m/T-g value diminishes with increasing small molecule content, whereas the value remains slightly changed by the copolymerization of different amounts of styrene on the acrylate chains. These results demonstrate that the compelling opposite change in m and T-g in the small molecule-loaded system is dominated by enthalpic intermolecular interactions. A distinct reduction of in in relation with small molecules was observed in poly(butyl methacrylate), where a methyl group attached to the same C atom of the hydrogen bonding ester group. The impact difference of size, number, and steric hindrance of phenolic groups in small molecules, as well as the chemical structure of polymers, on the mixture's fragility and T-g was discussed based on the generalized entropy theory of glass formation.