Photon transmission technique for studying swelling and drying kinetics of heterogeneous gels formed with various cross-linker contents


Yildiz S. , HEPUZER Y., YAGCI Y. , PEKCAN O.

EUROPEAN POLYMER JOURNAL, cilt.38, ss.1591-1599, 2002 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 38 Konu: 8
  • Basım Tarihi: 2002
  • Doi Numarası: 10.1016/s0014-3057(02)00050-2
  • Dergi Adı: EUROPEAN POLYMER JOURNAL
  • Sayfa Sayıları: ss.1591-1599

Özet

Bifunctional polytetrahydrofuran (PTHF) macromonomer was synthesized by the termination of living polymerization of tetrahydrofuran (THF) initiated by triflic anhydride and subsequent termination by sodium methacrylate. PTHF macromonomer thus prepared was copolymerized with methyl methacrylate (MMA) by free radical polymerization to yield networks in various cross-linker densities. These PTHF-PMMA gels were used for swelling experiments in chloroform vapor. Drying processes were monitored after removing the gels from the solvent vapor. Photon transmission from PTHF-PMMA gels was monitored during swelling and drying processes using UV-visible spectrophotometer. Transmitted light intensities, I-tr from these gels decreased when they are subjected to chloroform vapor. Decrease in I-tr was attributed to the heterogeneous lattice structure of PTHF-PMMA gels which appeared during swelling. Decrease in I-tr was modeled using Li-Tanaka equation from which time constants, tau(1) and tau(1)' and cooperative diffusion coefficients, D-0 and D-0' were determined. Increase in I-tr, after removing of vapor from the cell was observed and attributed to the decrease in heterogenity of lattice structures during drying of the corresponding gels. Time constants, tau(2) for drying processes were also determined. (C) 2002 Elsevier Science Ltd. All rights reserved.