Chemistry chain extension with diol

The rates of some of these competitive reactions of urethane chemistry, as determined from model compound studies, are shown in Table II. It can be seen that such knowledge is of vital importance in understanding the relative rates of chain extension, branching and crosslinking in the reaction of diisocyanates with both simple and polymeric diols, diamines, etc. 

TTie extension of tandem catalysis to polymer chemistry is, however, not trivial. In order to reach high molecular weight polymers, each reaction has to proceed with almost perfect selectivity and conversion. Obviously, combining different catalytic reactions limits the choice of suitable reactions since they must also be compatible with each other. We recently introduced Iterative Tandem Catalysis (ITC), a novel polymerisation method in which chain growth during polymerisation is effectuated by two or more intrinsically different catalytic processes that are both compatible and complementary. If the catalysts and monomers are carefully selected, ITC is able to produce chiral polymers from racemic monomers, as was shown by us for the ITC of 6-MeCL and the DKR polymerisation of sec-diols and diesters. ... 

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