3.4 Organo-Mineral Composites

Organic and inorganic polymer mixtures were chosen as organo-mineral composites (OMC). The organic polymer used is the product of MDI (crude dihpenylmethane diisocyanate) curing, and the inorganic polymer is the product of waterglass curing (waterglass is liquid glass, i.e., a solution in water of SiO ₂).

Polyisocyanates can initiate tripolymerization reactions in the presence of a catalyst, leading to the formation of strong triisocyanurate cycles [67]. Alkalis, acetates, alcoholates of alkali metals, tertiary amines, and many other substances are efficient catalysts of diisocyanate trimerization [50, 55, 57]. However, many of these catalysts proved to be of low effciency for trimerization of industrial polyisocyanates containing large quantities of impurities. Consequently, two catalysts-an alkaline medium formed by sodium waterglass and a tertiary amine [2,4,6-tri(dimethylaminomethyl)phenol]-were used for the polyisocyanate trimerization process.

The organic component (polyisocyanate) and the inorganic component of the OMC (sodium waterglass) constitute a poorly combined two-phase system. The use of interphase catalysts in heterophase systems is well known [103, 106]. The search for an inter-phase catalyst for our system suggested MGF-9 oligoetheracrylate for this purpose. Oxyethyleneglycol fragments can adopt the crown configuration in the MGF-9 chain structure and the presence of sodium silicate ions together with MGF-9 in our system allows formation of complexes between waterglass sodium cations and oxyethyleneglycol fragments of MGF-9 oligoetheracrylate similar to crown type:

Crown-complexes and their open-chain analogs, of which MGF-9 may considered one, are known to act as catalysts carrying ions in two-phase processes and to be efficient catalysts of...