Synthesis and characterization of acrylic polyols and polymers from soybean oils for pressure-sensitive adhesives

Abstract

A new class of acrylic polyols was synthesized from epoxidized soybean oil (ESO) and free-radically polymerized via UV irradiation to form pressure-sensitive adhesives (PSAs). ESO first was partially acrylated, then the remaining epoxy groups were dihydroxylated to make acrylic polyols. The acrylic polyols were characterized with Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, and hydroxyl value measurements. The degree of acrylation and hydroxyl functionality were carefully controlled to obtain polymers with a good balance of flexibility, crosslinking, and polarity, which are key attributes of PSAs. The glass transition temperature, rubbery plateau modulus, and cross-link density of polymers increased as the amount of acrylic polyol and the acrylate functionality of the resin increased. Biobased PSA with a good balance of peel strength (>4 N in⁻¹), tack (>7 N in⁻¹), and shear resistance (>50 000 min) was achieved. Positive correlations between the mechanical performance and viscoelastic responses of a frequency sweep of the PSAs were found.