Enhanced Mechanical and Adhesion Properties in Sustainable Triblock Copolymers via Non-covalent Interactions

ABA triblock copolymers are used as thermoplastic elastomers (TPEs) for a wide variety of applications. Herein, we describe incorporation of sugar-based glassy components to create sustainable triblock copolymers as alternatives for commodity TPEs. Poly(glucose-6-acrylate-1,2,3,4-tetraacetate) [PGATA] and poly(acetylated acrylic isosorbide) [PAAI] end blocks were chain-extended from a poly(n-butyl acrylate) [PnBA] midblock. PAAI-PnBA-PAAI exhibited excellent adhesion properties: peel = 8.74 N cm^-1, loop tack = 2.96 N cm^-2, no shear failure up to 100 h, and shear adhesion failure temperature (SAFT) = 60 °C. Although similar peel adhesion and higher loop tack were observed for PGATA-PnBA-PGATA, the shear strength and SAFT were moderate (18 h and 42 °C, respectively). PAAI-PnBA-PAAI are tough elastomers and demonstrated high stress and elongation at break (σ = 6.5 MPa and ϵ = 620%, respectively) while the GATA-based analogue exhibited weaker tensile properties (σ = 0.8 MPa and ϵ = 476%). To address this, the anomeric hydroxyl groups of GATA units were selectively deprotected to promote self-complementary hydrogen bonding in the glassy domains, resulting in 80% enhancement in the ultimate tensile stress at break (σ = 1.5 MPa). This study aims to demonstrate effects of noncovalent interactions, such as chain entanglements and self-complementary hydrogen bonding, to enhance the adhesion and mechanical performance of sugar-derived TPEs.