环形聚苯乙烯的稀溶液性质——Ⅱ.第二维利系数

DILUTE SOLUTION PROPERTIES OF RING-SHAPED POLYSTYRENE Ⅱ. THE SECOND VIRIAL COEFFICIENTS

第二维利系数（A2）是表征高分子链段间和高分子溶剂分子间相互作用的参数。对于环形高分子的第二维利系数,最早Casassa曾做过计算。利用“双接触”模型,Casassa计算了环形高分子的第二维利系数(A2r)为A2r=（NαβN2/2M2）[1-Cz+O（z2）]式中M为聚合物的分子量,Nα为Avogadro常数,N为高分子链段数,β为表征链段对排斥体积的二元集团积分,Z为排斥体积参数。式中系数C对环形或线形分子数值不同。

Using a low angle laser light scattering photometer (LALLS) the second virial coefficients(A_2) of ring-shaped and linear polystyrene (RPS and LPS) samples were determined in both toluene and butanone solutions. The A_2 of RPS in the good solvent (toluene) is smaller than that of LPS with the same molecular weight, but in the poor solvent (butanone) these two are very close. For RPS in the molecular weight range of 4×10~4——2.2×10~5, we haveA_(2r)=1.28×10^(-2)M_w^(-0.283) (Toluene 25℃) and A_(2r)=5.06×10^(-2)M_w^(-0.273) (Butanone 25℃).