Theory of Transient Polymer Networks Crosslinked by Two Different Associative Groups

概要

論文の詳細を見る
Co-associating polymers (CAP) are new type of polymers carrying two different species of associative groups along the polymer backbone. Transient gels of CAP show many new interesting thermodynamical and rheological properties such as network inversion, reentrant gelation etc. In this paper, we study linear viscoelasticity of physical gels formed by CAP on the basis of transient network theory. Model CAP to be treated here are difunctional (A-B) and trifunctional (A-A-B) linear polymers, where A and B stand for the associative groups. It turns out that the dynamic shear moduli of difunctional (heterotelechelic) A-B polymers behave like a Maxwell fluid with a single relaxation time τAB=1/(βA+βB), where βi(i =A, B) are the dissociation rates of associative groups from the network junctions. On the other hand, shear moduli of trifunctional A-A-B polymers are well described by the two-mode Maxwell model with two relaxation times τAB and τAA=1/(2βA) when A groups are much less frequently dissociated from the junctions compared with B groups. In such case, structural transformations of the network are expected to occur at a characteristic frequency ω≈1/ τAB where two distinct rubbery plateaux meet.
日本レオロジー学会の論文