Reactivity ratios determination and NMR characterization of 2-hydroxy ethyl methacrylate and methyl methacrylate copolymers

Abstract

Reaction of 2, 2'-dipyridylamine (DPA) with hexafluorophosphoric acid (HPF6) in methanol generates white rod-shaped crystals of HDPA.PF6,H 2O. The salt is characterised by C, H and N analyses, FT-IR, 1H NMR, mass spectroscopy and molar conductance measurement. The X- ray crystal structure of the salt has been determined. The structure shows that the salt is monomeric. The amine nitrogen is strongly hydrogen bonded with oxygen atom of water. Two pyridyl rings are almost planar which is a rarity in the coordination chemistry of DPA. Semi- empirical AM1 calculation was also Abstract : NMR has proven to be one of the most informative technique for the investigation of copolymer microstructure as chemical shifts are sensitive to compositional and configurational sequences of copolymers. The HEMA/MMA copolymers were prepared by free radical bulk polymerization at 70 oC. The copolymer composition was determined from 1H NMR spec trum which is then used to determine the reactivity ratios. The reactivity ratios obtained from KT, EVM and least square methods are r HEMA = 0.98, r MMA = 0.82; r HEMA = 0.88, r MMA = 0.81 and r HEMA = 0.92, r MMA = 0.81 respectively. 1 H and 13 C{ 1 H} NMR spectra were analyzed with the help of DEPT, 2D HSQC and 2D TOCSY spectrum. The long range interactions of carbonyl carbon with methoxy protons and oxy methylene carbon with hydroxyl proton were determined with the help of heteronuclear multiple bond coherence (H MBC) spectrum. With the help of 2D spectra it was found that carbonyl, α-methyl and quaternary carbon of HEMA and MMA unit were sensitive to various configurational sequences as in poly(2-hydroxy ethyl methacrylate) and poly(methyl methacrylate). The carbonyl and