Dynamic crosslinked poly(acrylic acid-co-acrylonitrile)/polyethylene glycol networks as reworkable adhesives

Abstract

The classical covalent network structure is of significant importance to the durability and performance of thermosetting acrylic adhesives; however, its intrinsic unrecyclable property also brings heavy environmental burdens of end-of-life waste disposal. Herein, we demonstrate a robust strategy for developing recyclable and reworkable thermosetting acrylic adhesives. To realize this purpose, a rigid acrylic copolymer (PA2N) containing highly adhesive nitrile groups and curable acrylic acid groups was firstly synthesized from acrylic acid and acrylonitrile, and then directly crosslinked with flexible bis-epoxy capped polyethylene glycol (PEG) through exchangeable β-hydroxyl ester linkages. The obtained PA2N/PEG network exhibits a maximum lap-shear adhesion strength of 4.97 MPa on Al sheets, which is competitive with a series of state-of-art reworkable adhesives and typical commercially available adhesives. Upon heat stimulation, the network could “on-demand” decrosslink and rearrange through the transesterification reactions between PA2N backbone and PEG crosslinker, endowing the as-prepared thermosetting acrylic adhesive with extraordinary recycling and reworking ability, which presents an adhesion performance recovery ratio of ca. 91.8% after 15 min of heat treatment at 190 °C. Overall, this work provides a robust approach in developing reworkable and sustainable alternative to traditional acrylic thermosetting adhesives.