Structure and properties of dangling chain poly(urethane-isocyanurate) model networkst

Abstract

A new trend in design of functional crosslinked systems is their preparation from specially designed precursors. A model endlinked network is the one in which all the precursor polymers become elastic chains. In real networks, however, imperfections cause the elastic properties of the networks to diminish. These imperfections include dangling chains, which are attached to the network at one end only, at equilibrium deformation, they do not contribute to the retroactive force of the network. In this project we prepared model networks with isocyanurate(hexahydro-l,3,5-triazin-2,4,6-trion) ring as a crosslink points based on 2,4-Tolylene diisocyanate and α,ω, dihidroxypoly (oxypropylene)diols by tertiary amine catalytic cyclotrimerisation in a bulk. The controlled content of dangling chains was obtained by partial substitution of polyol with monool component in synthesis of telechelic diisocyanates. The properties of networks were estimated by multiple extractions in organic solvent, differential scanning calorimetry, dynamic-mechanical analysis, photoelastical measurements. The network topology was calculated using the stochastic theory of branching processes. The thermal stability of some extracted and non-extracted samples was characterized by TGA and simultaneous TG/DSC thermal analyzer SDT Q600 TA Instruments. © 2010 American Chemical Society.