高度支化共聚物的均方回转半径和支化度的关系

对于聚合物的均方回转半径和支化度的关系, 过去鲜有定量研究, 这是由于具有不同支化度的系列同种聚合物样品较难合成之故. 1982年, Kricheldorf等1]报道了AB2和AB型单体的共缩聚反应, 这种反应可以方便地通过调节AB2和AB型单体的比例来控制产物的支化度.

Relationship Between Mean-square Radius of Gyration and Degree of Branching for Highly Branched Copolymers

This work deals with the dependence of the z-average mean-square radius of gyration ( z) on the degree of branching(DB) for highly branched copolymers made from the one-pot cocondensation of AB2 and AB monomers. A new expression of the degree of branching has been derived. The DB monotonously increases with increasing A group conversion and the fraction of AB2 monomers. The value of DB calculated in accordance with our formula is lower than that given by Frey and coworkers. Howerver, when the reaction approaches completion, our expression of the degree of branching degenerates into the equation reported by Frey. Furthermore, the z-average mean-square of gyration of the resulting copolymer in the Θ state has been derived on the basis of the classical work developed by Stockmayer, Gordon, Li and Ba. The relationship between DB and z is illustrated by numerical results. The z-average mean-square radius of gyration of the copolymer with a certain weight-average molecular weight monotonously decreases with increasing the degree of branching.