Paving the Way to Sustainable Waterborne Pressure-Sensitive Adhesives Using Terpene-Based Triblock Copolymers
Résumé
Emerging pressure-sensitive adhesives (PSAs) formulations based on triblock copolymers typically rely on solvent-borne or bulk processes and are mostly composed of petroleum-derived monomers. Herein, we aim to go beyond the status quo and synthesize hard–soft–hard and soft–hard–soft triblock copolymers using tetrahydrogeraniol acrylate (THGA) and cyclademol acrylate (CDMA) as biosourced monomers. Great care is taken on the synthesis of the monomers and polymers thereof to minimize the environmental impact of the entire process. Hence, the copolymers are obtained by reversible addition–fragmentation chain transfer (RAFT) miniemulsion polymerization as a waterborne process. The process is readily scalable, as no intermediate purification of the first block is required. Good control is achieved for the triblock copolymers with high molecular weight, with Mn ≈ 105 500 g·mol–1 and Đ ≈ 1.6 for the PTHGA-b-PCDMA-b-PTHGA. The nanophase segregation of the copolymers is later evidenced by atomic force microscopy (AFM) and rheological measurements. Finally, the formulations show good adhesive performance, in comparison to triblock copolymers partially based on styrene.