Unusual behavior in light scattering experiments of poly(N-vinylimidazole) prepared by precipitation polymerization
Unusual behavior in light scattering experiments of poly(N-vinylimidazole) prepared by precipitation polymerization
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DOI：
10.1007/s00396-009-2104-2
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发表时间：
2009-09
影响因子：
2.4
通讯作者：
M. Masaki;K. Ogawa;E. Kokufuta
中科院分区：
文献类型：
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作者：
M. Masaki;K. Ogawa;E. Kokufuta
以2，2 '-偶氮二异丁腈（AIBN）为引发剂，苯为溶剂，采用两种不同的单体/引发剂比例，通过沉淀聚合法合成了聚N-乙烯基咪唑（PVI）。溶液聚合也用以下引发剂/溶剂系统进行：AIBN/水-甲醇混合物（按体积计1：1）和4，4 '-偶氮双（4-氰基戊酸）/HCl水溶液（pH 0.8）。通过动态光散射（DLS）检查PVI在乙醇和0.2 M NaCl（pH 3，含HCl）中的所有四种制剂。从溶液聚合的每个制剂的DLS数据的CONTIN分析显示在乙醇和水性溶剂中的单峰分布。通过静态光散射（SLS）在这些不同溶剂中的摩尔质量之间获得了良好的一致性。然而，在与上述相同的条件下，来自沉淀聚合的聚合物在DLS中表现出不均匀的双峰分布，这表明参考文献[6]（Savin等人，Macromolecules 37：6565）中的SLS数据在理解PVI的溶液行为中引起严重错误。
Poly(N-vinylimidazole) (PVI) was synthesized by the precipitation polymerization using 2,2’-azobis(isobutyronitrile) (AIBN; initiator) and benzene (solvent) at two different monomer/initiator ratios. The solution polymerization was also performed with the following initiator/solvent systems: AIBN/water–methanol mixture (1:1 by volume) and 4,4’-azobis(4-cyanovaleric acid)/aqueous HCl solution (pH 0.8). All the four preparations of PVI in ethanol and in 0.2 M NaCl (pH 3 with HCl) were examined by dynamic light scattering (DLS). The CONTIN analysis of DLS data for each preparation from the solution polymerization showed a unimodal distribution in both ethanol and aqueous solvents. A good agreement was obtained between the molar masses in these different solvents by static light scattering (SLS). However, the polymers from the precipitation polymerization exhibited a heterogeneous bimodal distribution in DLS under the same conditions as above, indicating that the SLS data as in reference [6] (Savin et al. Macromolecules 37:6565) cause a serious error in the understanding of solution behavior of PVI.