A fluorescence study on dissolution of polymeric glasses prepared in various molecular weights


Pekcan O., Ugur S.

JOURNAL OF COATINGS TECHNOLOGY, cilt.75, ss.55-63, 2003 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 75 Konu: 944
  • Basım Tarihi: 2003
  • Doi Numarası: 10.1007/bf02757862
  • Dergi Adı: JOURNAL OF COATINGS TECHNOLOGY
  • Sayfa Sayıları: ss.55-63

Özet

Poly(methyl methacrylate) (PMMA) discs in various molecular weights, M-w, were prepared by free-radical polymerization of methyl methacrylate (MMA). Pyrene (P) was introduced during polymerization as a fluorescence probe to monitor the gelation and dissolution processes in chloroform vapor and solvent, respectively. In-situ steady state fluorescence (SSF)-experiments were performed to monitor vapor uptake,and chain desorption processes. Direct illumination of PMMA discs were performed to excite the P molecules embedded inside the PMMA glass. Variation in P intensity, I, was monitored during the swelling of the PMMA material exposed to chloroform vapor. It was observed that PMMA film swells like a crosslinked polymeric gel at early times by obeying the Li-Tanaka equation. Swelling time constants, tau(c), of PMMA discs were measured and found to have a strong correlation with the molecular weight, of PMMA. IN a separate experiment, when the PMMA discs were in chloroform, desorption of PMMA chains from glass discs was monitored by observing the change of pyrene fluorescence intensity. A diffusion model with a moving boundary was employed to quantify the fluorescence data observed from dissolving PMMA discs made at various molecular weights. It was observed that desorption coefficient, D, decreased by increasing M-w by obeying the Dapproximate toM(w)(-1) law.