Abstract
2-Hydroxy-3-(1-naphthyloxy)propyl methacrylate (NOPMA) monomer was synthesized from reaction of 2-[(2-naphthyloxy)methyl]oxirane with methacrylic acid in the presence of pyridine. The polymerization of NOPMA was carried out by free radical polymerization method in the presence of AIBN at 60 °C. The structure of monomer and polymer was characterized by 1H-NMR, 13C-NMR and FT-IR spectroscopy techniques. The glass transition temperature and average-molecular weights of poly(NOPMA) were measured using differential scanning calorimetry and gel permeation chromatography, respectively. The thermal degradation behavior of poly(NOPMA) has been investigated by FT-IR studies of the partially degraded polymer and thermogravimetry. The cold ring fractions (CRFs) were collected at two different temperatures, initially fraction-1 (CRF1) is from room temperature to 320 °C, and the other fraction-2 (CRF2) is from 320 to 500 °C. The volatile products of the degradation were trapped at −195 °C (in liquid nitrogen). All the fractions were characterized by FT-IR, 1H and 13C-NMR spectroscopic techniques, and the cold ring fractions (CRFs) were also characterized by GC–MS. For the degradation of polymer, the major compound between products of CRFs is α-naphthol. The GC–MS, FT-IR and NMR data showed that depolymerization corresponding to monomer was not prominent below 320 °C in the thermal degradation of poly(NOPMA). The mode of thermal degradation containing formation of the major products was identified. The dielectric permittivity (ε′), the loss factor (ε″) and conductivity (σac) were measured using a dielectric analyzer in the frequency range of 50 Hz to 20 kHz.
Highlights
Many studies on thermal behavior of methacrylate polymers have been reported for a long time
We report on the preparation of poly(NOPMA) and thermal degradation behavior from ambient temperature to 320 °C and 500 °C
Poly(NOPMA) having various functional side groups such as hydroxyl, carbonyl, ether and aryl was synthesized by free radical polymerization method at 70 °C in the presence of 1,4-dioxane using AIBN as initiator
Summary
Many studies on thermal behavior of methacrylate polymers have been reported for a long time. The researches necessary to undertake on the thermal degradation of polymers are important in view of the many applications depending on their thermal stability. To accomplish this goal, many characterization methods including gas chromatography–mass spectrometry (GC–MS), thermal analysis and spectroscopic techniques, etc., [4] have been used. The thermal behavior of methacrylate polymers having a polar functional side group such as C=O, O–H can change via interchain and intra-chain of the side groups which results in cyclization, crosslinking, and so on [6,7,8]. The chemical structure of a polymer having a reactive side group may change through interchain and intra-chain of the side groups resulting in the formation of a cross-linked and cyclic ladder structure during degradation of the polymer [12,13,14]
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