An in situ strategy to produce high-performance composite thermal adhesives with excellent bonding, thermal transfer and adjustable electrical performance based on a designer hyperbranched epoxy copolymer

Abstract

Thermally conductive adhesives (TCAs) have attracted considerable attentions in recent years as they can simultaneously promote interfacial bonding and thermal transfer. So far, a lot of strategies have been explored for producing them. Among them, modifying adhesive resins with thermally conductive nanofillers is one of the most frequently reported methodologies, which often involves complicated process and tedious procedures. We herein report a facile strategy for producing TCAs via an in situ process with the assistance of a designer hyperbranched epoxy copolymer, HBPE@PGMA. This copolymer consists of a hyperbranched polyethylene (HBPE) core and multiple poly (glycidyl methacrylate) (PGMA) side chains, which can be synthesized under mild conditions by a two-step polymerization process. As a stabilizer, this copolymer is found to effectively promote the exfoliation of hexagonal boron nitride (h-BN), natural graphite or multi-walled carbon nanotubes (MWCNTs) in chloroform under sonication, rendering boron nitride nanosheets (BNNS), graphene and individually dispersed MWCNT, respectively. Meanwhile, some of the copolymer can be irreversibly adsorbed on the resultant nanofiller surface based on the noncovalent CH-π interactions. This makes them well dispersible in chloroform and allows us to obtain high-performance TCAs from their dispersions via in situ process directly using the copolymer as matrix. The resultant TCAs simultaneously exhibit excellent interfacial bonding, thermal transfer and adjustable electrical performance. This strategy paves a way for producing high-performance TCAs through in situ process with relatively simple process.