Vegetable Oil-Derived Polyamide Multiblock Copolymers toward Chemically Recyclable Pressure-Sensitive Adhesives

A series of poly[amide11-alt-poly(dimer acid-alt-1,5-diamino-2-methyl)] multiblock copolymers [PA11Hx-alt-(DA-MP)Sy] with high renewable content (up to 95%) was synthesized via bulk polycondensation of a plant oil-based diacid-terminated PA11 hard block (PA11Hx) and a diamine-terminated PA soft block [(DA-MP)Sy] (wsoft block = 0.31–0.90). The tunable and superior mechanical properties (E = 4–233 MPa, σyield = 20–33 MPa, σb = 744–2233%, and γ = 222–359 MJ m–3) of the PA11Hx-alt-(DA-MP)Sy depended on the chain lengths of both the crystalline hard block and the amorphous soft block. The performance of the pressure-sensitive adhesive (PSA) system that includes the multiblock was assessed, revealing a peel strength of 3.52 N cm–1, a probe tack of 0.45 N, and shear strength of >50 000 min, which are competitive to commercial PSA tape. The molecular structure of the PA11Hx-alt-(DA-MP)Sy was analyzed by 1H NMR, 13C NMR, FTIR, TBN, and GPC. High-purity monomers were recovered through acid-catalyzed hydrolysis of a sustainable multiblock copolymer with >99% conversion rate (calculated based on crude 1H-NMR analysis). These novel multiblocks and the chemical recycling method could provide a potential for sustainability.