Hot-melt pressure-sensitive adhesives containing high biomass contents

A hot-melt pressure-sensitive adhesive (PSA) was generated containing a high content of renewable biomass. The polymer is based on a commercial hot-melt acrylic formulation containing primarily 2-ethylhexyl acrylate (EHA). The new polymer is synthesized with a majority of the EHA replaced with a macromonomer (MM) prepared with l-lactide and μ-caprolactone via catalyzed bulk ring-opening polymerization using N-hydroxyethyl acrylamide as the initiator. Incorporation of the MM into the polymers was confirmed via proton NMR. The properties and adhesive performance of the new polymer were compared with those of its 100% acrylic commercial version. When synthesized using the same approach, the biomass-containing PSA had a lower molecular weight, higher glass transition temperature, and lower melt viscosity. Introduction of MM had little impact on the tack force, shear time, and shear adhesion failure temperature, and the peel strength increased substantially. It is expected that these hybrid materials can be optimized for a variety of self-adhesive applications.