摘要
本文用动态膜渗透压及粘度法测定了短链聚苯乙烯的分子量M_n,第二virial系数A_2及特性粘数[η]。到聚苯乙烯(2.5×IO^3<M<1.5× 10~4)在甲苯、氯仿及丙酮中30℃的[η]-M关系与文献报道θ条件下(环己烷,34.5℃)的关系式基本相同,依从[η]=8.8×10^(-2)M^(0.05).在低分子量范围内,A_2随M减小急剧增大,渗透压数据与文献值汇集得出A_2~[os]=KM^(-1.6),并且A_2~[os]值明显高于光散射所得的值。但是,由粘度数据按Flory粘度理论和Stockmayer-Fixman式计算的均方迥转半径<s^2>,均方末端距<h^2>以及扩张因子a_(?)均与报道值一致.本工作表明,分子量大约在400—1.5×10~4之间,为聚苯乙烯从小分子到高分子的过渡区,此时短链聚苯乙烯以蠕虫形链存在于溶液中。
The melecular weights M_n, second virial coefficients A_2, and intrinsic viscosities [η] of short chain polystyrenes hane been measured by dynamic membrane osmometry and viscosimetry. The [η]-M relations for polystyrene (2.5×10~3<M<1.5×10~4) in toluene, chloroform and acetone respectively were closo to one another, and in agreement with the literature data for polystyrene in cyclohexane at 34.5℃, which is represented as [η]=8.8×10^(-2)M^0.50. In the range of M stydied the value of A_2 increased rapidly with decreasing M. In the same molecular weight range, the osmotic pressure results, combined with literature data, yielded A_2^(os)=KM^(-16), and A_2^(os) was always higher than that from light scattering. However mean square radius of gyration <S^2>, end-to-end distance <h^2>, and expansion factor α_8, calculated from viscosity values according o Flory viscosity theory and Stockmayer-Fixman equation consisted with the literatures. These results imply that in the region of M from 400 to 1.5×10~4 for the polystyrene there is a transition from small molecule to macromolecule, and the short chain polystyrene in dilute solution exists as a wormlike chain.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1990年第6期616-621,共6页
Acta Chimica Sinica
