Thermotropic Networks Based on Poly(Methyl Vinyl Ether)

Reyntjens, Wouter; Jonckheere, Laura; Goethals, Eric J.

doi:10.1081/ma-120016669

Cited by 1 publication

(2 citation statements)

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“…One possible exception involves a hydrogel composed of PMVE and PHEMA segments that exhibited an opaque to clear transition upon heating in water that may have been due to reswelling of the PHEMA segments at higher temperatures. 39 In this paper HEMA-based polymers that exhibit SÀI and in many cases SÀIÀS transitions are described. The polymers are made water-soluble by limiting the degree of polymerization or by adding hydrophilic comonomers such as MAA, DMAEMA, [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MO-ETAC), or [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC), as shown in Scheme 1.…”

Section: ' Introductionmentioning

confidence: 99%

“…While there has been interest in thermally responsive polymers containing HEMA or related hydroxy-containing monomers, − there has been little focus on the possibility of redissolving these (co)polymers at higher temperatures (an I–S transition) through breaking of H-bonds. One possible exception involves a hydrogel composed of PMVE and PHEMA segments that exhibited an opaque to clear transition upon heating in water that may have been due to reswelling of the PHEMA segments at higher temperatures …”

Section: Introductionmentioning

confidence: 99%

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Thermally Responsive 2-Hydroxyethyl Methacrylate Polymers: Soluble–Insoluble and Soluble–Insoluble–Soluble Transitions

Longenecker

Hanna

et al. 2011

Macromolecules

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2-Hydroxyethyl methacrylate (HEMA)-based (co)polymers showed soluble to insoluble (S–I) thermoresponses, as measured by turbidimetry, when heated in aqueous solutions of appropriate ionic strength and/or pH. Surprisingly, many of the polymers showed a second insoluble to soluble (I–S) thermoresponse at higher temperatures, probably as a result of breaking of polymer–polymer H-bonding that allowed redissolution of the polymer chains. The thermoresponse of the charged copolymers was very sensitive to the polymer concentration, pH, and ionic strength likely due to the role of charge screening in the chain collapse and aggregation necessary to observe cloud points. Urea, a commonly used “H-bond breaker”, raised the cloud point (and decreased the clearing point for systems that showed I–S transitions); however, subsequent cooling or heating runs in the presence of urea often showed dramatically different thermoresponses as a result of urea hydrolysis, leading to a pH change and/or polymer hydrolysis at high temperature. Marked hysteresis or changes from run to run were seen for some systems because of polymer precipitation or slow rehydration of phase-separated material or, in some cases, slow hydrolysis of HEMA units.

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Section: ' Introductionmentioning

confidence: 99%