The unperturbed state of dendrimers

摘要

We report a theoretical study of the unperturbed state of dendrimers, which is realized when the second virial coefficient becomes equal to zero. This condition is achieved through a vanishin of the intermolecular free energy, which is obtained by mubual compensation of the two- and three-body interactions betweeen two molecules. This procedure, which permits us to determine the temperature of dendrimers as a function of their beneration, is coupled to the problem of the intramolecular conformation, determined by minimization of the intramolecular free enerrgy. The latter accounts for the two-and three-body interactions within he molecule, and for the cofigurational entropy. We find that the temperature si a decreasing function of the dendrimer generation g, thedecrease becoming relatively fast at large g, but is alomst independent of the number of segments(one or two in our case)between adjacent branch points. At the temperature, the residual three-body interactions within the molecule not compensated by the two-body attractions induce a significant swelling over the random-walk conformation for g>2