Synthesis of polyurethane particles in supercritical carbon dioxide using organocatalysts or organocatalytic surfactants

Abstract

The influence of amine oxide catalysis has been investigated in the dispersion polymerisation of 2,4-toluenediisocyanate with 1,4-butanediol in supercritical carbon dioxide. In reactions stabilised by a diisocyanate terminated polydimethylsiloxane (PDMS) macromonomer, the concentration of N-methylmorpholine N-oxide (NMO) catalyst has an impact on both the molecular weight and particle morphology of the polyurethanes (PUs) produced. Leading on from this, amine oxide catalyst groups have been grafted onto PDMS chains in order to construct catalytic surfactants or ‘catasurfs’. At a sufficient concentration of the catasurf and with an appropriate molecular weight of PDMS, well-defined PU particles of micrometric size are produced. Furthermore, the PDMS can subsequently be removed from the particles to yield a PU material of high purity.