Browsing by Author "Hassler, Joseph, F"

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    Supporting data for Preparation and characterization of H-shaped polylactide
    (2024-05-16) Zografos, Aristotelis; Maines, Erin, M; Hassler, Joseph, F; Bates, Frank, S; Hillmyer, Marc, A; hillmyer@umn.edu; Hillmyer, Marc, A; University of Minnesota Department of Chemistry
    These files contain primary data along with associated output from instrumentation supporting all results reported in Zografos et al. Preparation and Characterization of H-Shaped Polylactide. In Zografos et al. we developed an efficient strategy for synthesizing H-polymers. An H-polymer has an architecture that consists of four branches symmetrically attached to the ends of a polymer backbone, similar in shape to the letter ‘H’. Here, a renewable H-polymer efficiently synthesized using only ring-opening transesterification is demonstrated for the first time. The strategy relies on a tetrafunctional poly(±-lactide) macroinitiator, from which four poly(±-lactide) branches are grown simultaneously. Proton nuclear magnetic resonance (1H-NMR) spectroscopy, size exclusion chromatography (SEC), and matrix assisted laser desorption/ionization (MALDI) spectrometry were used to verify the macroinitiator purity. Branch growth was probed using 1H-NMR spectroscopy and SEC to reveal unique transesterification phenomena that can be controlled to yield architecturally pure or more complex materials. H-shaped PLA was prepared at the grams scale with a weight average molar mass Mw > 100 kg/mol and narrow dispersity Ð < 1.15. Purification involved routine precipitations steps, which yielded products that were architecturally relatively pure (~93%). Small-amplitude oscillatory shear and extensional rheology measurements were used to demonstrate the unique viscoelastic behavior associated with the H-shaped architecture.