Polyethylene-like Polyesters: Strategies for Tailoring Mechanical Properties and Adhesion Performance

Polycondensation of hydrogenated α,ω-dihydroxy polybutadiene soft blocks, hydrogenated α,ω-dihydroxy poly-(cis-cyclooctene) hard blocks, and succinic anhydride was utilized to synthesize high-density polyethylene-like (HDPE-like) and olefinic block copolymer-like (OBC-like) polyesters. The thus-prepared AABB-type long-spaced aliphatic polyesters (LSAPEs) exhibit tunable crystallinity, mechanical performance, and adhesion properties. Small- and wide-angle X-ray scattering (SAXS, WAXS) analyses revealed an increase in long-period values of the HDPE- and OBC-like polyesters from 25 to 36 nm and a gradual decrease in their crystallinity from 64% to 39% with increasing soft block content, resulting in lower density of the materials. Differential scanning calorimetry confirmed discrete block copolymer structures, as the melting temperature of the materials was preserved at the level of 118.8-127.8 °C, while the crystallinity degree decreased with increasing soft block content. Dynamic mechanical thermal analysis demonstrated that the viscoelastic properties of LSAPEs are comparable to those of commercial HDPE and OBCs. Comparing these AABB-type LSAPEs with recently reported AB-type analogues having lower molecular weight hard blocks and differently branched soft blocks revealed some interesting results. Furthermore, we investigated the adhesion of these polyolefin-like polyesters to aluminum and were able to support our findings with molecular dynamics simulations. The presence of only a limited number of ester functionalities and carboxylic chain-end groups provides a 20-fold higher adhesion to aluminum than the HDPE benchmark. This study demonstrates that polyolefin-like polyesters (LSAPEs) enable access to versatile materials revealing tunable mechanical and thermo-mechanical properties resembling those of various polyolefins, with significantly enhanced adhesion properties.