Free radical copolymerization of methyl methacrylate with methacrylic monomers derived from salicylic acid. Microstructural analysis, chain flexibility and hydration behaviour of the prepared copolymers
C. Elvira et al., Free radical copolymerization of methyl methacrylate with methacrylic monomers derived from salicylic acid. Microstructural analysis, chain flexibility and hydration behaviour of the prepared copolymers, POLYMER, 40(25), 1999, pp. 6911-6924
Copolymers of methyl methacrylate (MMA), and the methacrylic monomers deriv
ed from salicylic acid, 2-hydroxy-4-methacrylamidobenzoic acid (4-HMA), and
2-hydroxy-5-methacrylamidobenzoic acid (5-HMA), were prepared by free radi
cal polymerization in N, N-dimethylformamide, DMF, solution at 50 degrees C
using 2, 2'-azobisisobutyronitrile (AIBN), as initiator. Fineman-Ross and
Kelen-Tudos linearization methods, as well as the Tidwell and Mortimer non-
linear least-squares treatment were used to calculate the monomers reactivi
ty ratios, giving the Tidwell and Mortimer values from the 95% confidence d
iagrams, the most probable ones r(4) = 0.83, r(M) = 1.52 and r(5) = 0.29 r(
M) = 2.15, The microstructural analysis of the prepared copolymers was perf
ormed by C-13 (75.5 MHz) nuclear magnetic resonance (NMR) spectroscopy, in
terms of sequence distribution and stereochemistry of monomeric units along
the copolymer chains. The stereochemical parameters sigma* = sigma(4M) = s
igma(M4) = 0 21 and sigma* = sigma(5M) = sigma(M5) = 0.19 were determined f
rom the C-13 NMR spectra of the copolymers 4-HMA-MMA and 5-HMA-MMA, respect
ively. Also the T-g of the corresponding homopolymers and copolymers, were
analysed by differential scanning calorimetry (DSC) in terms of the Fox equ
ation. Hydration degree of the prepared copolymers was studied in compariso
n to poly (4-HMA), poly (5-HMA) and poly (MMA). (C) 1999 Elsevier Science L
td. All rights reserved.