Thermally Degradable Poly(n-butyl acrylate) Model Networks Prepared by PhotoATRP and Radical Trap-Assisted Atom Transfer Radical Coupling.

Michael R Martinez,Megan Treichel,Julia Cuthbert,Mingkang Sun,Joanna Pietrasik,Krzysztof Matyjaszewski,Ziye Zhuang

doi:10.3390/polym14040713

Abstract

Model poly(n-butyl acrylate) (PBA) networks were prepared by photoinduced atom transfer radical polymerization (photoATRP), followed by curing of polymer stars via atom transfer radical coupling (ATRC) with a nitrosobenzene radical trap. The resulting nitroxyl radical installed thermally labile alkoxyamine functional groups at the junctions of the network. The alkoxyamine crosslinks of the network were degraded back to star-like products upon exposure to temperatures above 135 °C. Characterization of the degraded products via gel permeation chromatography (GPC) confirmed the inversion of polymer topology after thermal treatment.

Highlights

Crosslinked polymer networks are versatile materials with mechanical properties tunable by both chemical composition and topology [1]
Four-arm polymer stars were prepared by photoATRP of BA from a tetrafunctional α-bromoisobutyrate core (4f-BiB) using the grafting-from approach (Scheme 2) [43,47,48,49]
PhotoATRP enables the synthesis of polyacrylates and methacrylates using ppm loadings of copper catalyst by continuous regeneration of the CuBr/L activator by reduction of the CuBr2/Me6TREN deactivator with excess tertiary amines as the reducing agent [43,47,48,49]

Summary

Introduction

Crosslinked polymer networks (commonly referred to as gels, elastomers, or thermosets) are versatile materials with mechanical properties tunable by both chemical composition and topology [1]. Polymer networks have been successfully used as soft elastomers [2,3,4,5], membranes [6,7], porous materials [8,9], pH responsive gels [10], and medical devices [11]. The topology of a polymer network is influenced by the curing conditions. Networks prepared by (free) radical polymerization, reversible addition fragmentation chain transfer (RAFT), and atom transfer radical polymerization (ATRP) demonstrated subtle differences in swelling ratios and rheology due to nuances in crosslinking chemistry, despite an identical chemical composition [12]

Methods

Results

Conclusion