Small-angle neutron scattering study on specific polymerization loci induced by a copolymerization of polymerizable surfactant and styrene in miniemulsion polymerization
Small-angle neutron scattering study on specific polymerization loci induced by a copolymerization of polymerizable surfactant and styrene in miniemulsion polymerization
复制标题
细乳液聚合中可聚合表面活性剂与苯乙烯共聚引发的特定聚合位点的小角中子散射研究
DOI：
10.1021/ma301776b
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发表时间：
2012
期刊：
影响因子：
5.5
通讯作者：
R. Motokawa
中科院分区：
文献类型：
--
作者：
梶山万悠子;藤田恭子;劉遠;中村暢文;大野弘幸;Synthesis of Nitrogen-bridged Dithienopyrrole Derivatives;R. Motokawa
我们研究了在可聚合surfactantN-n-dodecyl-N-2-methacryloyloxyethyl-N，N-二甲基溴化铵(C12DMAEMA)与苯乙烯(St)细乳液聚合的早期阶段，产生具有双峰凝胶渗透色谱轮廓的共聚粒子的特殊聚合位置的起源。研究了C12DMAEMA细乳液聚合过程中粒子形成与聚合时间的关系，并与不可聚合表面活性剂十六烷基三甲基溴化铵(CTAB)进行了比较。用C12DMAEMA或CTAB对St进行微乳化，然后在聚苯乙烯(PST)的存在下，用2，2‘-偶氮二(2-氨基丙烷)盐酸盐(V50)或油溶引发剂2，2’-偶氮二(异丁腈)(AIBN)在60℃进行聚合。凝胶渗透色谱(GPC)和元素分析间接预测了ST/C12DMAEMA/V50聚合体系中两个不同的聚合位置。用时间分辨小角中子散射(SANS)直接观察和检测了细乳液聚合溶液中的特定聚合轨迹。C12DMAEMA和聚(C12DMAEMA-RAN-St)不能完全稳定聚合初期ST/C12DMAEMA/V50/PST体系中形成的液滴，形成大的聚集体。通过在水相中形成均匀的分散体，球形液滴在随后的聚合(tp>；20分钟)中稳定下来。相反，在St/CTAB/V50/PST中，CTAB稳定的液滴在整个聚合过程中保持其尺寸和形状。结果表明，在ST/C12DMAEMA/V50/PST和ST/CTAB/V50/PST两个聚合体系中，粒子的大小强烈依赖于聚合早期形成的液滴的大小。SANS的POOD分析为ST/C12DMAEMA/V50/PST聚合体系在液滴表面的早期聚合提供了直接证据，是凝胶渗透色谱双峰的来源。
We have investigated the origin of a specific polymerization loci that yielded copolymer particles with a bimodal gel permeation chromatographic profile in the early stage of miniemulsion polymerization of styrene (St) with the polymerizable surfactantN-n-dodecyl-N-2-methacryloyloxyethyl-N,N-dimethylammonium bromide (C12DMAEMA). The formation of particles by miniemulsion polymerization using C12DMAEMA was investigated as a function of the polymerization time (tp) and was compared with that using the nonpolymerizable surfactant cetyltrimethylammonium bromide (CTAB). St was miniemulsified with C12DMAEMA or CTAB and was polymerized with either a water-soluble initiator, 2,2′-azobis(2-amidinopropane) dihydrochloride (V50), or an oil-soluble initiator, 2,2′-azobis(isobutyronitrile) (AIBN), at 60 °C in the presence of polystyrene (PSt) as a hydrophobe. Gel permeation chromatography (GPC) and elemental analysis indirectly predicted two different polymerization loci in the St/C12DMAEMA/V50 polymerization system. Time-resolved small-angle neutron scattering (SANS) was used to directly observe and examine the specific polymerization loci in the miniemulsion polymerization solutions. The droplets formed in the St/C12DMAEMA/V50/PSt at the initial stage of the polymerization were not fully stabilized by C12DMAEMA and poly(C12DMAEMA-ran-St) and were found to build up the large aggregates. The spherical droplets were stabilized later in the polymerization (tp> 20 min) by forming a homogeneous dispersion in the water phase. In contrast, the droplets stabilized by CTAB in St/CTAB/V50/PSt maintained their size and shape throughout the polymerization. As a result, in both polymerization systems of St/C12DMAEMA/V50/PSt and St/CTAB/V50/PSt, the particle size was found to depend strongly on the size of the droplets formed in the early stage of polymerization. Porod analysis of the power law scattering observed by SANS provided direct evidence for the specific polymerization loci, which appeared in the early stage of the polymerization system of St/C12DMAEMA/V50/PSt on the surface of the droplet, and was the origin of the bimodal peaks in the GPC chromatogram.