Polyhydroxyalkanoate block polymer adhesives derived from long-chain aliphatic β-lactones and lactide

Abstract

Pressure sensitive adhesives (PSAs) are contained in numerous packaging products as labels, tapes, and sealants. Consequently, they are a common contaminant that complicates repulping during paper recycling and industrial composting. Degradable PSAs are an attractive alternative where complete removal or separation is not practical. In this work, we employed epoxide carbonylation to produce β-tridecalactone to prepare poly(β-tridecalactone) (PTDL) through ring-opening transesterification polymerization (ROTEP). We explored the synthetic challenges in producing high molar mass (>20 kg mol⁻¹) PTDL. These include dehydration of the propagating chain end and adventitious initiation from impurities in the monomer. The utility of PTDL PSAs containing a rubbery midblock with semicrystalline poly(L-lactide) (PLLA) end blocks was probed as a function of composition, molar mass, and processing conditions. The largest PLLA volume fraction (f_PLLA = 0.31–0.35) triblock polymers exhibit commercially competitive peel strengths (5.5 ± 0.9 N cm⁻¹) and loop tack (8.5 ± 0.9 N cm⁻¹) values, with properties similar to office and duct tapes. This work informs how long aliphatic chain containing β-lactones can be effectively harnessed to produce high performance PSAs with the end goal of fully biodegradable adhesives.