Effect of Molecular Weight on Performance Properties of Pressure-Sensitive Adhesive of Poly (2-ethylhexyl acrylate) Synthesized by RAFT-Mediated Miniemulsion Polymerization

Reversible addition-fragmentation chain transfer (RAFT) polymerization has been applied in the synthesis of controlled molecular weights and dispersity of poly (2-ethylhexyl acrylate) (PEHA) by the miniemulsion technique. The RAFT agent (2-cyanoethyl morpholine-4-carbodithioate) was synthesized and used for 2-ethylhexyl acrylate (2-EHA) polymerization at molecular weights of 2 × 10⁵, 7 × 10, 14 × 10⁵, and 20 × 10⁵ Da and polymerization reaction kinetics were studied. The RAFT agent was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H-nuclear magnetic resonance (¹H-NMR) spectroscopy, and mass spectroscopy. The synthesized emulsions were characterized by gel permeation chromatography, particle-size analysis, x-ray diffraction (XRD) analysis, and rheological characterization. The PEHAs were used as adhesives for coated and uncoated laminates with low and high surface energies and materials, and their properties such as tack, lap shear strength, peel strength, and shear holding strength were assessed.