This study investigated the influence of reaction conditions on monomer incorporation and sequence distribution in l-lactide-based macromonomers (MMs) for hybrid acrylic polymers. Hydroxyethyl methacrylate (HEMA)-initiated MMs composed of l-lactide and ε-caprolactone were synthesized via stannous octoate-catalyzed, Sn(Oct)2, ring-opening polymerization (ROP). l-lactide propagates more rapidly than ε-caprolactone, with the selectivity (S) decreasing from 12.9 to 3.9 as temperature increases from 100 to 130 °C. 13C nuclear magnetic resonance spectroscopy (NMR) confirmed that temperature and catalyst level promote transesterification, increasing the degree of randomness (R) from 0.51 to 0.76. When incorporated at 50 wt % into water-based pressure-sensitive adhesives (PSAs), these MMs showed strong microstructure-dependent performance. Low-R (blocky) MMs yielded higher tack and peel strength, whereas higher-R MMs provided substantially greater shear resistance. Water contact angle also increased with R. These results show that MM sequence can be tuned through synthesis conditions to tailor adhesive performance.
Watcharakitti et al. (Tue,) studied this question.