Segmented Polyhydoxyurethane as Novel Non-Isocyanate Polyurethane Functional MaterialsPublic Deposited
Polyurethane (PU) is an important commodity polymer with a broad range of applications. Increasing regulations on isocyanates have prompted investigations into alternative routes to PU. Cyclic carbonate aminolysis leading to polyhydroxyurethane (PHU) is a promising alternative. This dissertation describes the first fundamental investigation of the synthesis and properties of segmented, nanophase-separated PHUs as thermoplastic elastomer. The hydroxyl groups and soft-segment choice are critical to the development of nanophase separation and elastomeric properties. Nanophase separation in segmented PHUs made with polytetramethylene oxide (PTMO)-based soft segment is accompanied by broad interphases having a wide range of local composition due to some level of phase mixing from hard-segment hydroxyl groups to soft-segment ether oxygen. Consequently, PTMO-based PHUs exhibit potential as sound and vibration damping materials over broad temperature ranges, a function unattainable by conventional, neat thermoplastic PU (TPU) elastomer. Nanophase separation can be significantly tuned via judicious choice of soft segment. PTMO-based soft segments yield nanophase-separated PHUs with broad interphase whereas polybutadiene-co-acrylonitrile (PBN)-based soft segments yield nanophase-separated PHUs with a much sharper domain interphase similar to that of conventional TPU. Using three carbonate hard-segment structures having motifs similar to commonly used diisocyanates, it is demonstrated that both hard-segment and soft-segment structures often cooperatively influence the nanophase separation and properties of PHUs. The impact of chain extender structure on the properties of PHUs was investigated. Norbornane-based chain extender enables significant improvement in the properties of PHUs. The impact of amide-based diamine diamide (DDA) chain extender on the properties of PHUs was investigated. DDA chain extender enables significant improvement in nanophase separation and properties of PHU systems where significant phase mixing were previously observed. Finally, the impact of hydroxyl group functionalization on the properties of PTMO-based PHU was investigated. Hydroxyl group functionalization leads to loss of nanophase separation due to disruption to interurethane hydrogen bonding indicating that interurethane hydrogen bonding is important to the formation of nanophase-separated PHU.
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