Abstract: The cohesive interaction among polymer chains in methyl methacrylate-naphthyl ethylene copolymer solution was studied by NMR relaxation. ¹³C NMR relaxation times of methyl methacrylate-naphthyl ethylene copolynler in its good solvent deuteriochloroform were measured at different temperatures. The T₁ values of individual carbon atoms of methyl methacrylate-naphthyl ethylene copolymer in solution increase as the temperature increases, which is characteristic of the NMR relaxation of small molecules in solution. ¹H NMR transverse relaxation of protons attached to carbons of this copolymer shows biexponential behavior, which corresponds to two states of the copolymer. The fast relaxating conponent decreases with increasing temperature, corresponding to the disentanglement of cohesional entangled chains. When tempreature becomes even higher, this component of the main chain start to increase again, this shows that new entanglements occurs among copolymer main chains. Results also show that in this copolymer system, the interlocking interaction of the side group-naphthyl rings is scarce.

Key words: Copolymer, Relaxation, Cohesional entanglement