Priyank N. Shah

Environmentally benign synthesis of vinyl ester resin from biowaste glycerin

We present here for the first time a novel environmentally benign protocol for the synthesis of vinyl ester resin (VER). Our synthetic strategy utilizes a commercial waste material, glycerin, from biodiesel manufacturing and converts it into a widely utilized resin. The VER was synthesized using bisphenol A (BPA) and glycidyl methacrylate (GMA) as precursors. GMA was synthesized via a multistep synthetic protocol using glycerin obtained from a biodiesel manufacturing waste stream. The structure of the intermediates was confirmed by 1H NMR, HPLC and FT-IR spectroscopy.

Arrangement of C60 via the self-assembly of post-functionalizable polyisocyanate block copolymer.

Poly(furfuryl isocyanate) (PFIC), which includes the reactive furan group, was synthesized by anionic polymerization using a sodium benzhydroxide (Na-BH), self-assembly initiator. We determined the optimum polymerization conditions by varying both the reaction time and the molar ratio of the monomer to the initiator. Block copolymer, poly(furfuryl isocyanate)-b-poly(n-hexyl isocyanate), was synthesized under optimized polymerization conditions. The PFIC was modified by Diels-Alder reactions with C60 for functionalization. Transmission electron microscopy (TEM) was used to study the self-assembly of block copolymers and modified block copolymer with C60. C60 formed highly ordered aggregates on the PFIC domains via self-assembly of the block copolymer.

Structural characterization of telechelic polyisobutylene diol

The chemical homogeneity of telechelic polyisobutylene diol (PIB-diol), prepared by hydroboration-oxidation of allyl telechelic PIB obtained by reacting living PIB with allyltrimethylsilane, was investigated by liquid chromatography at critical conditions (LCCC) and HPLC coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A normal phase gradient HPLC method was developed that was able to separate the as-synthesized PIB-diol into three components; PIB-diol, PIB-monool and PIB without any OH functionality. These were analyzed by MALDI-TOF MS, which suggested that the reaction of living PIB with allyltrimethylsilane was incomplete. LCCC using refractive index (RI) detector as a concentration detector allowed separation and quantification of PIB species according to their chemical heterogeneity (PIB-diol=95.3%, PIB-monool=3.3%, non-functional PIB=1.4%). The calculated number average functionality (Fn) of PIB-diol=1.94 suggests high quality of PIB-diol suitable for high molecular weight polyurethane synthesis.

Effects of Catalyst Concentration on the Morphology and Mechanical Properties of Polyisobutylene-based Thermoplastic Polyurethanes

We studied the morphology and mechanical properties of a series of polyisobutylene-based thermoplastic polyurethanes (TPUs) with the same composition, but synthesized with tin (II) 2-ethylhexanoate catalyst concentrations ranging from 0.04 to 1 mol% relative to 4,4′-methylenebis(phenyl isocyanate) (MDI). All of the TPUs were found to have incomplete microphase separation between the soft segment (SS) and hard segment (HS), and the degree of microphase separation was not significantly affected by catalyst concentration. However, changing the catalyst concentration resulted in a substantial change in the microphase separated structure. Such differences may arise from the difference in the average chain length distribution of HS, which was confirmed by oxidation of the TPUs. Interestingly, the catalyst concentration also had a dramatic effect on the mechanical properties of these TPUs. When the catalyst concentration was at or below 0.1 mol%, the TPUs exhibited ultimate tensile strength of 20–21 MPa, compared to 10 MPa when the catalyst concentration was at or above 0.4 mol%. These results may help better understand the structure-property relationships of TPUs, and more importantly, develop biostable TPUs with high mechanical strength.