Nonreactive Nonaqueous Dispersants

The nonreactive NAD are structures without polymerisable double bonds, but have a remarkable stabilisation effect on polymeric dispersions in polyether media. The main characteristic of such kinds of nonreactive NAD is to have an organic segment with high affinity for the carbocatenary vinylic polymer chemically linked to a high molecular weight polyether chain, which has a high affinity for the continuous liquid polyether matrix. 

One such type of NAD is obtained by the reaction of a crude, alkaline, high molecular weight polyether of 6000 daltons, with a liquid epoxy resin having two epoxy groups (for example diglycidyl ether of bisphenol A). 

After the reaction, developed in normal conditions of alkaline ring opening reactions, at 110-130 °C, the addition product is purified by classical methods, such as by treatment with adsorbents or by neutralisation - crystallisation techniques [58, 59]. 

This kind of NAD, resulting from the reaction of crude or pure MDI with high molecular weight polyether triols, is very efficient in stabilising copoly (ACN - styrene) dispersions or even polystyrene dispersions in polyether polyols. 

Generally, the nonreactive NAD is used in higher concentrations, than the macromers in graft polyether polyols synthesis, of around 10-15% compared to the final polymer polyol. 

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