MONTE-CARLO SIMULATION OF PHASE-TRANSITIO N OF RANDOM COPOLYMER SYSTEMS

Three Dimensional Monte Carlo simulation of phase transitions is perfo rmed at high density of polymers with limited chain length by introduc ing intramolecular conformational interaction E(c) and intermolecular orientation-dependent interaction E(p), the later is considered as the process of compact pairing of non-bond segments according to our ''co operative pairing model'', We prove that at E(p)/E(c) = 1, the phase t ransition corresponds to polymer crystallization (Fig, 1,2), Then by r andomly introducing non-crystallizable segments which do not take part in cooperative pairing process, we find that the phase transitions mo ve to lower temperature(Fig.3) and the depression of melting temperatu res follows Flory's prediction for random copolymer, accompanying the loss of lamellar structure which agrees with experiments, These result s illustrate that the cooperative pairing model is a special behavior for crystallizable segments.