No abstract

A series of [poly­(l-lactide)–poly­(dimer acid methyl ester-alt-poly­(propylene glycol))–poly­(l-lactide)] n (PLLA–PDP–PLLA) n multiblock copolymers was synthesized in a three-step procedure: PLLA–PDP–PLLA (LDPL) triblock copolymers were synthesized using ring-opening polymerization of l-lactide with PDP macroinitiators, which was prepared via step-growth melt polycondensation based on biodiesel and macro-diol, followed by chain extension of the LDPL triblock with 4,4′-methylenebis­(phenyl isocyanate). Molecular characterization revealed that the synthetic procedures yielded the desired triblock and multiblock copolymers (f PLLA = 0.22–0.27). The relationship between thermal behavior and morphology indicated microphase separation into two domains in both the triblocks and multiblocks. Compared to previously reported triblocks with a high molar mass and PLLA hard blocks with inaccessible order–disorder transition temperature (T ODT) values, the multiblock architectures in this study were found to become disordered at much lower temperatures (T ODT = 82–128 °C). To prepare (LDPL) n multiblocks, coupling low-molar-mass LDPL triblocks without free-standing thin films led to dramatically enhanced tensile properties. The self-adhesive performance of the pressure-sensitive adhesive (PSA) system including the multiblocks was evaluated, showing a peel strength of 3.1 N cm–1, a probe tack of 1.9 N, and static shear strength of >50 000 min, which are values comparable to those of current PSAs. These biodiesel-based thermoplastic elastomers hold promise for sustainability and high value-added economy.

Renewable polyurethane microcapsules containing isosorbide derivatives for self-repairing anticorrosion coatings were easily manufactured by interfacial polymerization of a dimer ester–diisocyanate (DE–TDI) prepolymer derived from waste vegetable oil and 1,4-butanediol (BD) as a chain extender using ultrasonication. Two kinds of corrosion inhibitors were also synthesized by the ring-opening reaction of succinic anhydride (SA) or maleic anhydride (MA). Microcapsules having 11–38 μm in diameter were obtained, and the typical core content of microcapsules was around 40–45 wt %. Salt spray tests used for evaluating self-healing anticorrosion coating systems showed significant rust retardancy, depending on the content of the isosorbide derivatives for corrosion control.

Renewable thermoset elastomers were prepared using the plant-based monomer carvomenthide. Controlled ring-opening transesterification polymerization of carvomenthide using diethylene glycol as an initiator gave α,ω-dihydroxyl poly(carvomenthide) (HO-PCM-OH), which was subsequently converted to carboxy-telechelic poly(carvomenthide) (HOOC-PCM-COOH) by esterification with excess succinic anhydride through a one-pot, two-step process, leading to no crystallinity, high viscosity, strong thermal resistance, and low glass transition temperature of the resulting functionalized polyester. Thermal curing processes of the resulting 3, 6, and 12 kg mol(-1) prepolymers were achieved with trifunctional aziridine to give cross-linked PCM elastomers. The thermal properties, mechanical behavior, and biocompatibility of the rubbery thermoset products were investigated by differential scanning calorimetry, thermal gravimetric analysis, dynamic mechanical analysis, tensile tests under static and cyclic loads, and cell adherence. These new materials are useful candidates to satisfy the design objective for the engineering of a variety of soft tissues.