Drying polyaddition

A series of Ji-conjugated organoboron polymers were successfully prepared by simple polyaddition between aromatic diynes and mesitylborane in a dry TTTF solution (Table 1). The polymerization preceeded smoothly at room temperature without catalyst to afford the corresponding polymers whose Mn were in the range of several thousands. 

Chemical Drying. Chemically drying paints contain binder components that react together on drying to form cross-linked macromolecules. These binder components have a relatively low molecular mass, so that their solutions can have a high solids content and a low viscosity. In some cases, solvent-free liquid paints are possible. Chemical drying can occur by polymerization, polyaddition, or polycondensation. 

In drying by polyaddition, low molecular mass reactive polymers such as alkyd resins, saturated polyesters, or polyacrylates react with polyisocyanates or epoxy resins to form cross-linked macromolecules. Because this reaction can take place at room temperature, the binder components must be mixed shortly before application. The period of time during which a coating of this type remains usable after mixing of the components is known as the pot life. These are known as two-pack coatings, differing from the one-pack systems, which can be stored for months or even years. 

Physico-chemical drying/curing. Polyeondensation or polyaddition are combined with evaporation of organie solvents. 

Wholly aromatic Pis like Kapton, insoluble in common organic solvents, are usually synthesized through a two-step method PI precursors, high molecular weight poly(amic acid)s (PAAs) are readily synthesized from ring-opening polyaddition of an extra-pure dianhydride and an equimolar diamine in aprotic amide solvents such as A,A-dimethylacetamide (DMAc) and A-methyl-2-pyrrolidone (NMP), then the as-cast dried PAA films are subjected to thermal or chemical imidization. The reaction scheme and the abbreviations of polymers and monomers are shown in Fig. 1. 

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