聚苯乙烯在热力学半良溶剂丁酮中的稀溶液性质

The Dilute Solution Properties of Polystyrene in Butanone as Thermodynamically Semigood Solvent

用光散射、速度沉降和粘度法研究了宽分子量范围的窄分布聚苯乙烯样品在热力学半良溶剂丁酮中的稀溶液行为,与聚苯乙烯在θ溶剂和良溶剂中的文献数据相比较,讨论了聚苯乙烯的稀溶液性质.

The dilute solution behaviour of polystyrene samples with narrow molecular weight distribution,their molecular weight ranging from 1×10^(4)to 18.9×10^(6),in butanono as thermodynamically semigood solvent at 20℃was studied by light scattering,velocity sedimentation and viscometry methods.The following relations were obtained.<R^(2)>^(1/2)=1.96×10^(-9)M^(0.546)(cm)S_(0)=4.15×10^(-15)M^(0.462)(s)k_(s)=6.54×10^(-2)M^(0.594)(cm^(3)/g)[η]=2.93×10^(-2)M^(0.605)(cm^(3)/g)The relations of polystyrene samples in toluene at 20℃using velocity sedimentation experiment were as follows:S_(0)=3.06 x 10^(-15)M^(0.428)(s)k_(s)=4.68×10^(-2)M^(0.668)(cm^(3)/g)The results obtained were compared with the literature data of polystyrene in theta and good solvents.It was found that for the relation<R^(2)>^(1/2)∝M^(v)the dynamic exponent v_(τ)obtained from velocity sedimentation was near to the other dynamic exponent v_(η)from viscometry and the dynamic value vr or vηwas different from the static exponent v_(τ)from light scattering.Similarly,the dynamic expansion factorαf is close to the other dynamicαη,but smaller than the static valueα_(Ls).Flory-Fox’s viscosity parameterφis strongly dependent on molecular weight of sample and solvent used.The parameterφdefined byφ=[η]M/[f]^(3)seems to be considered as a universal constant,its value being 1.35×10^(21)mol^(-1.)Having estimated the unperturbed dimension,the interaction parameter B and the binary cluster integralβaccording to B-S-F-Y equation and Baumann’s equation,the comparison of the results obtained was made.