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Chris Schaller, Chemistry


Recent advances in polymer production sciences have led to an increase in research in sustainable practices. Our efforts intended to produce a toughened biorenewable multiblock copolymer. Polylactide has been noted to be produced by sustainable practices but is limited because of the fragile structure. To improve the brittle behavior of polylactide, preparation of polylactide-b-polybutadiene-b-polylactide multiblock copolymers were synthesized with a fixed weight of dihydroxyl polybutadiene (~3000 and ~2000g/mole series) and variable volume percent (50-90%) of both semicrystalline poly(L-lactide) and amorphous poly(D,L-lactide). Producing a multiblock copolymer intended to strengthen the mechanical properties by bridging and gapping over several domains. Initially, triblock polymers were catalyzed with a ring opening polymerization and characterized. Toluene diisocyanate (TDI) and terephtaloyl chloride (TCL) were used to couple the triblock copolymers to form multiblock structures. Characterization of these products was accomplished by differential scanning calorimetry, small angle X-ray scattering, 1H-NMR spectroscopy, size exclusion chromatography, dynamic mechanical analysis, and tensile testing, leading to an extensive set of thermal and mechanical properties of both the triblock and multiblock copolymers. The data collected indicated a controlled product with a clear enhancement of mechanical properties of polylactide. Trends were associated with the weight percent of polylactide and this can be used in future work as we explore other aspects of this material. This research can be continued by experimenting with other blending options, measuring other aspects of the toughness of the material, and investigating other coupling agents to initiate the multiblock synthesis.


This research was supported by funding from the NSF, awarded to the Center for Sustainable Polymers, University of Minnesota, Minneapolis, MN.

This presentation was alternately titled "Characterization of Poly(lactide-b-butadiene-b-lactide) Multiblock Copolymers."