Collapse of a flexible polymer chain II

2014 This note gives a physical description of the collapse transition for a long chain (Nmonomers) near the 0398 point, based on existing renormalization group calculations. 1) at T = 0398 exactly, the chain is ideal as regards the size (R ~ N1/2) and the virial coefficient vanishes. However, some repulsive correlations remain due to 3 body interactions ; 2) for temperatures T = 0398 + 0394T, a sufficiently long chain can be pictured as a sequence of blobs, each with GB monomers GB = (0398/0394T)2 (ln |0398/0394T|)-3/11 . Inside each blob, the 0398 conditions still hold. But on a larger scale, the string of blobs shows excluded volume behaviour (if T > 0398) or collapse, with R ~ N1/3 (if T 0398). The singular part of the free energy is of order kT per blob : this gives a specific heat divergence of (ln |0398/0394T|)3/11. A better probe could be obtained with UV spectra, measuring the number of monomer-monomer contacts. LE JOURNAL DE PHYSIQUE 2013 LETTRES ,~’ TOME 39, 1 er SEPTEMBRE 1978, Classification Physics Abstracts 61.40K201364.70 .