Abstract
Thiol-ene click reactions are used to synthesize segmented thermoplastic materials for the first time via a soft segment + hard segment + chain extender approach that is commonly used to synthesize thermoplastic polyurethane elastomer (TPU). We employ a relatively long chain difunctional thiol (2500 g/mol) as soft segment, a small-molecule thiol as chain extender, and rigid cyclic-ene monomers, including norbornene (containing either urethane or urea linkages in the backbone) and maleimide, as hard segments to achieve thiol-norbornene and thiol-maleimide thermoplastics. The majority of the thiol-norbornene polymers synthesized with 45% or 55% urethane-based norbornene hard segments exhibit phase separation with broad interfaces as indicated by dynamic mechanical analysis (DMA) and hold promise as both thermoplastic elastomers competitive with TPUs and broad-temperature-range damping materials. Thiol-norbornene polymers synthesized with 50% urea-based norbornene hard segments are nanophase separated with sharp interfaces (as indicated by DMA and small-angle X-ray scattering) due to the stronger interurea hydrogen bonding as compared with interurethane interactions. The low strain at break (∼30%) and high Young's modulus (200-300 MPa) suggest that the 50% hard segment forms the matrix in these polymers, disallowing elastomeric response. Segmented thiol-maleimide thermoplastics, synthesized without isocyanates at 45% and 50% hard-segment content, exhibit highly effective nanophase separation and properties indicating potential to be competitive with some thermoplastic non-isocyanate polyurethane (NIPU) elastomers and TPUs.
Original language | English (US) |
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Pages (from-to) | 3620-3631 |
Number of pages | 12 |
Journal | Macromolecules |
Volume | 51 |
Issue number | 10 |
DOIs | |
State | Published - May 22 2018 |
Externally published | Yes |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry