Carbocatenary vinylic polymer

Both radicals, I and the radical generated on the polyetheric chains, initiate the radical polymerisation of vinylic monomers. The radical I leads to the formation of ungrafted carbocatenary vinylic polymer. The polyetheric radical generates the formation of graft species ... 

During the radical polymerisation of vinylic monomers in liquid polyether media, graft species (carbocatenary vinylic polymer chemically linked on the polyether) are formed, by chain transfer reactions, which play the role of a true NAD. For grafting reactions on polyether triols, the graft species have the following idealised structure (Figure 6.3). 

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. 

The utilisation of low molecular weight transfer agents, which control the molecular weight of the carbocatenary vinylic polymer, is a very effective way to obtain low viscosity polymer dispersions at high solid concentrations. 

When using a macromer as a NAD, a high macromer content copolymer, called a comb polymer , is formed first. After the consumption of 1-3% of the total quantity of vinylic monomers, the resulting high macromer content copolymer is self-organised in the similar spherical proto-particles, which turn the reaction mass from transparent to opaque, with the carbocatenary polymeric part situated inside the spheres and the polyetheric chain situated outside the sphere, in the continuous liquid polyether phase. The next steps are identical to those of nonreactive NAD. The particles formed remain constant in number but increase in particle diameter size, the final diameter being around 10-20 times higher than the initial proto-particle diameter, of around 0.3-1 pm. 

---