CONICET | Buscador de Institutos y Recursos Humanos

A starch-derived α-azide-ω-alkyne 1,4:3,6-dianhydrohexitol AB monomer and a novel symmetrical heterofunctional A2B2 aliphatic crosslinker, i.e. 2,2 bis(azidomethyl)-1,3-bis(O-propargyl) propanediol, were copolymerized at various molar ratios to generate bio-sourced networks through thermal 1,3-dipolar Huisgen polyaddition. The investigation of the crosslinking reactions through DSC analyses confirmed the highly exothermic character of the azide / alkyne cycloaddition (DH(total) = 232 +/- 5 KJ/mol of functional groups of type A or B), and clearly underlined a one-to-one relationship between the glass transition temperature and conversion. Experimental values of conversion at the gel point estimated from DSC and rheological measurements deviated significantly from the ideal mean-field theory of network formation, a behavior assigned to the occurrence of intramolecular cyclizations. Although a significant fraction of intramolecular cycles was generated during the curing process, the AB + A2B2 thermal 1,3-dipolar Huisgen polyaddition strategy afforded relatively high glass transition temperature polytriazole networks (Tg > 140°C) using versatile processing conditions and the absence of additives.