| || Polyethylene maleate copolyesters as coating materials for piezoelectric quartz crystal based chemical sensors
Author : Gupta, D. C.;Saxena, C.;Dubey, V.;Gutch, P. K.;Asrey, R.;Vyas, K. D.
Source : Defence Science Journal ; Vol:55(4) ; 2005 ; pp 505-514
Subject : 620.1 Material Science and Technology
Keywords : Sorbent coating material;Piezoelectrical crystal detector;Surface acoustic wave device;Organophosphorus compounds;Dimethylmethylphosphonate;Coating materials;DMMP;PEM;Chemical sensors;Polyethylene maleate
Abstract : Polyethylene maleate (PEM) was synthesised by direct polycondensation of maleic anhydride and ethylene glycol in toluene under reflux using p-toluene sulphonic acid as a catalyst. Structure of PEM was further modified by varying nature of diols and acid components, chain length of glycols, incorporation of aromatic and fluorine groups in the chain. Formation of PEM was monitored by gas chromatography. The parameters like degree of polymerisation, number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated from the extent of reaction and stoichiometric ratio of the reactants. The number average molecular weight was also determined using Knauer vapour pressure osmometer. Cohesive energy, volume, and solubility parameters of PEM-based copolyesters were calculated by group contribution method. These PEM-based copolyesters have been evaluated as sorbent-coating materials for the detection of organo phosphorus(OP)compounds using dimethylmethylphosphonate (DMMP) as model compound and piezoelectric crystal detector. PEM-bisphenol A is found to be the most sensitive and potential coating material for the detection of OP compounds using piezoelectric crystal detector. Potential PEM-based copolyesters have been characterised by viscosity, infrared spectroscopy, NMR spectroscopy, Mn and thermal stability.