The strength and flexibility of thermoset plastics are attributed to crosslinked polymer chains, making these materials of value for inclusion in paints, coatings and composites. However, thermoset plastics are difficult to recycle, as the crosslinks cause the materials to burn rather than melt when heated. Now these polymers can be rendered more amenable to recycling with a discovery made by researchers in the U.K.

Breakable bonds were introduced into different parts of a polymer gel structure through a reversible addition–fragmentation chain transfer polymerization process. The resulting poly(n-butyl acrylate) networks contained either cleavable crosslinks or cleavable strands. Testing demonstrated that while all the gels could be degraded to some extent, those with breakable bonds in the polymer chains retained their properties much better when reformed compared with materials that were broken down via the cross-linked bonds.

The University of Bath and University of Surrey researchers plan to devise a general road map of the best locations for these breakable bonds to better define why some bonds break more easily than others. Efforts will also be devoted to optimizing the system described in Polymer Chemistry for reprocessing and recycling other commercially used crosslinked polymer networks.