Mediating the slow dynamics of polyacrylates by small molecule-bridged hydrogen bonds

Yuanbiao Liu; Gaopeng Shi; Guozhang Wu

doi:10.1039/d2sm00453d

Mediating the slow dynamics of polyacrylates by small molecule-bridged hydrogen bonds

Soft Matter. 2022 Jun 15;18(23):4445-4454. doi: 10.1039/d2sm00453d.

Authors

Yuanbiao Liu^{1

2}, Gaopeng Shi¹, Guozhang Wu¹

Affiliations

¹ Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science & Engineering, East China University of Science & Technology, Shanghai 200237, China. wgz@ecust.edu.cn.
² School of Materials Science & Engineering, Shandong University of Technology, Zibo 255000, China.

PMID: 35648624
DOI: 10.1039/d2sm00453d

Abstract

This report studied the changes in the slow dynamics of polyacrylate by adding a hindered phenol (CA) capable of forming three intermolecular hydrogen bonds (inter-HBs) per molecule with the polymer chain. The CA molecule apparently diminishes the slow modes (with lower peak temperatures and peak heights) of the polyacrylate, although it has a higher glass transition temperature (T_g) than the acrylic matrix, and the rigid CA-bridged HB network significantly amplifies the α-relaxation near T_g (with higher peak temperatures and peak heights). Consequently, the mixtures exhibit a diminishing slow mode that gradually merges with the prominent α-peak with increasing CA loadings. The anomalous dynamics concerning the opposite behaviors of the slow mode and α-relaxation was further rationalized in terms of dissociation of inter-HBs when the temperature is higher than T_g, together with the small molecule-alleviated macromolecular connectivity. This work provides essential insights into the slow dynamics of such HB-driven hybrids, and paves the way for tailoring the viscous flow properties of the hybrid material from a molecular level perspective.