Thermotropic Networks Based on Poly(Methyl Vinyl Ether)

Abstract

Segmented polymer networks consisting of poly(methyl vinyl ether) (PMVE) and a second polymer were synthesized by copolymerization of PMVE-α,ω-bis-methacrylate with a hydrophilic vinyl monomer (hydroxyethyl methacrylate, HEMA) or a hydrophobic vinyl monomer (styrene, St or butyl acrylate, BA). Such networks, swollen to equilibrium in water, show thermotropic properties in the case of the PMVE-PSt and PMVE-PBA systems due to the lower critical solution temperature (LCST) properties of the PMVE segments. The PMVE-PHEMA networks showed an inverse thermotropic behavior, i.e., the swollen networks are turbid at lower temperature and become transparent at higher temperature. The PMVE-PSt networks containing a small fraction of PSt are the best materials for thermotropic properties because the swelling is limited to a few percent which results in materials free of cracks after repeated heating–cooling (with corresponding de-swelling–swelling) processes.

Keywords:

• Polymer networks
• Poly(methyl vinyl ether)
• LCSTL lower critical solution temperature
• Thermotropic behavior
• Segmented polymer networks

Acknowledgments

We thank the BASF Company (Ludwigshafen) for the donation of MVE. L.J thanks the IWT (Vlaams Instituut voor Wetenschappelijk-Technologisch Onderzoek) for a scholarship.