Tricritical points in polymer systems

PABLO SERRA; JURGEN F. STILCK

JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 1990 vol. 23 p. 5351 - 5367

1751-8113

Abstract. We consider a lattice model for equilbrium polymerisation in a solvent proposedby Wheeler and Pfeuty. We include attractive interactions between first-neighbourmonomers which belong to polymer chains but are not consecutive along a chain. In thelimit of no dilution this model describes the collapse transition of a polymer in a poorsolvent (@-point).When no attractive interaction is present the model is appropriate forsulphur solutions,, where a dilution tricritical point is observed. The thermodynamicproperties of the model were studied by two kinds of calculations. The solution on theBethe lattice shows a locus of tricritical points, including the 0 and dilution tricriticalpoints. On a fractal lattice ( 3 D Sierpinski gasket), the exact real space RG solution revealsthat the Theta-point and the dilution tricritical point belong to the same universality class.