Water-based polymer colloids with a branched chain architecture as low-gel pressure-sensitive adhesives

The performance of water-based acrylic pressure-sensitive adhesives, in which the latex particles had minimal gel content of typically less than a few percent and the polymer chains had a branched architecture, were investigated. A series of semi-batch emulsion copolymerizations of 2-octyl acrylate, isobornyl acrylate and acrylic acid was carried out in the presence of ethylene glycol dimethacrylate as crosslinker.

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The molecular weight distributions and branched chain topology were regulated by using 2-ethylhexyl thioglycolate as a chain-transfer agent. The monomers and chain-transfer agent were selected as these were already available as bio-based feedstocks, or had a realistic potential to become available from non-petrochemical resources. Adhesive films cast from the polymer dispersions demonstrated good peel, shear strength and tack adhesion energies. This is attributed to polymer chain branching, which unlocks a broader window for the design rules for pressure-sensitive adhesives. Detailed rheological studies of the viscoelastic materials were conducted to support the adhesive test results.

Source: Polymer Chemistry, Issue 28, 2024