Thermal and dynamic mechanical relaxation behavior of stereoregular poly(2‐hydroxyethyl methacrylate)

Abstract

Thermal, dynamic mechanical, and dielectric relaxation techniques were used to determine the relaxation behavior of isotactic and syndiotactic poly(2‐hydroxyethyl methacrylate) (pHEMA). Activation energies Ea were determined for the dielectric γ relaxation and compared with those of poly(2‐methoxyethyl methacrylate) (pMEMA) to determine the influence of hydrogen bonding on side‐chain relaxation processes. No difference in Ea was observed between syndiotactic pHEMA and atactic (predominantly syndiotactic) pMEMA. Isotactic pHEMA, however, had Ea + 1 kcal/mole higher than that of syndiotactic pHEMA. This was attributed to improved side‐chain packing in the isotactic polymer.

A broad spectrum analysis of the dielectric properties of poly(2-hydroxyethyl methacrylate)

“…The dielectric response of dry and hydrated PHEMA have been studied before but data obtained above 50 8C have not been previously reported [3,[7][8][9][10][11][12]. In mechanical studies dry PHEMA exhibits two sub-T g secondary relaxations and a primary glass transition.…”

“…The b relaxation often appears as a shoulder to the a peak and may even be unresolvable [3,9,12,13].…”

pH-sensitive hydrogels based on (meth)acrylates and itaconic acid

“…The pore size of the investigated samples decreases in the following order: Thermal Behavior of P(HEMA/IA/PAGM). Several T g values for PHEMA have been reported in the literature, with T g s ranging from 85 to 105 o C. [43][44][45] In our study, we examined the effects of composition on the thermal behavior of P(HEMA/ IA/PAGM) copolymers. For all P(HEMA/IA/PAGM) networks and the PHEMA homopolymer, a single T g value was observed, and there was a visible dependence of the T g value on the copolymer composition ( Figure 4).…”

Theoretical synthesis of poly‐(2‐hydroxyethylmethacrylate) by uniform localization of molecular orbitals calculation

“…Russel et al 15 used the closed packed space-(CPK) filling molecular model to explain the difference between the isotactic and syndiotactic stereoregular chains of P(HEMA), as shown Figure 3.…”

“…15 The statistically averaged geometry and statistical weights obtained from the conformational energy calculations have been used to determine the characteristic ratio…”