Fatty Acid-Based Triblock Copolymers with a Transient Network

The self-assembly and physical properties of triblock copolymers containing long-chain polyacrylate midblocks have been explored. Long-chain polyacrylates, which may be derived from fatty acids found in vegetable oils, are attractive as sustainable materials with biorenewable origins. The long alkyl side-chains of these polyacrylates provide a route to tunable physical behavior, yet also hinder their application due to lack of entanglements. Incorporation of a transient network was explored as a method to improve mechanical properties in triblock copolymers containing a midblock composed of a random copolymer of lauryl acrylate, a derivative of lauric acid, and acrylamide, which undergoes hydrogen bonding. Poly(styrene-b-(lauryl acrylate-co-acrylamide)-b-styrene) triblock copolymers exhibited spherical morphologies and elastomeric behavior. The polymers underwent a high extent of hydrogen bonding, which greatly impacted their domain size, order-disorder transition temperature, and rheological and mechanical behavior. Importantly, triblock copolymers with hydrogen bonding in the matrix exhibited significantly higher modulus, strain at break, and tensile strength as compared to polymers in the absence of hydrogen bonding.