A Guiding Principle for Toughening Cross-Linked Polymers: Synthesis and Application of Mobility-Controlling Rotaxane Cross-Linkers.

A Guiding Principle for Toughening Cross-Linked Polymers: Synthesis and Application of Mobility-Controlling Rotaxane Cross-Linkers.
Angew Chem Int Ed Engl. 2019 Jan 02;:
Authors: Sawada J, Aoki D, Otsuka H, Takata T
Abstract
Three-component mobility-controlling vinylic rotaxane cross-linkers with two radically polymerizable vinyl groups (RC_Rs) were synthesized to prove that the mobility of the components of the RC_Rs plays a crucial role in determining the properties of rotaxane-cross-linked polymers (RCPs). RC_Rs (R = H, Me, or Et) were obtained from the living ring-opening polymerization of six-membered cyclic carbonates with two substituents R at the 5 position using pseudorotaxane initiators with a terminal OH group on the axle. A mixture of n-butyl acrylate and 0.5 mol% RC_R was exposed to UV irradiation in the presence of a photoinitiator to afford the corresponding RCPs (RCP_R; R = H, Me, or Et). RCP_Et was prepared using RC_Et, which exhibits the lowest component mobility. The low component mobility is reflected in inferior mechanical strength and stretchability in tensile stress tests compared to components with good (R = Me) and high (R = H) mobility. However, RCP_Et exhibited significantly higher stress and strain values than the corresponding covalently cross-linked polymers (CCP_Rs). These results indicate that a suitable component mobility substantially enhances the mechanical strength of RCPs. This behavior could serv...

Source: Angewandte Chemie - January 2, 2019 Category: Chemistry Authors: Sawada J, Aoki D, Otsuka H, Takata T Tags: Angew Chem Int Ed Engl Source Type: research