Environmentally adaptable pathway to emulsion polymerization for monodisperse polymer nanoparticle synthesis
Environmentally adaptable pathway to emulsion polymerization for monodisperse polymer nanoparticle synthesis
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用于单分散聚合物纳米颗粒合成的环境适应性乳液聚合途径
DOI：
10.1016/j.polymer.2015.09.002
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发表时间：
2015
期刊：
影响因子：
4.6
通讯作者：
Mikio Konno
中科院分区：
文献类型：
--
作者：
Haruyuki Ishii;Naoto Kuwasaki;Daisuke Nagao;Mikio Konno
提出了一种环境适应性的乳液聚合方法，在表面活性剂浓度远低于常规乳液聚合的情况下制备单分散聚合物纳米颗粒。本方法是基于使用低临界胶束浓度（CMC）的表面活性剂，在低浓度的胶束存在下生成大量聚合物颗粒，并在反应早期停止胶束消失而产生颗粒，以达到颗粒的高单分散性的想法。采用疏水单体苯乙烯（St）和疏水单体甲基丙烯酸甲酯（MMA），以过硫酸铵（APS）为引发剂，十八烷基硫酸钠（SOS）为长烷基链表面活性剂，在总单体浓度为0.3 M的条件下进行乳液聚合。聚合是在APS浓度为20 mM的情况下进行的，使得SOS的CMC低至0.085 mM。MMA单体摩尔分数的增加增加了聚合物颗粒的数量，而高单体摩尔分数的MMA未能稳定颗粒的分散。在St/MMA = 1/1的单体比下，表面活性剂浓度为1 mM的聚合反应可以得到33 nm的单分散聚合物颗粒，该浓度高于其CMC (0.085 mM)，但远低于常规乳液聚合中几十mM的表面活性剂浓度。
An environmentally adaptable method is proposed for emulsion polymerization to produce monodisperse polymer nanoparticles at surfactant concentrations much lower than conventional emulsion polymerization. The present method is based on an idea of employing a surfactant with a low critical micelle concentration (CMC) to generate a large number of polymer particles in the presence of micelles at low surfactant concentrations and to cease the particle generation by the micelle disappearance in early reaction stage for attainment of high monodispersity of particles. A hydrophobic monomer of styrene (St) and a less hydrophobic monomer of methyl methacrylate (MMA) were used in the present emulsion polymerization at a total monomer concentration of 0.3 M with an initiator of ammonium persulfate (APS) and a long alkyl chain surfactant of sodium octadecyl sulfate (SOS). The polymerization was conducted at a high APS concentration of 20 mM that gave the CMC as low as 0.085 mM for SOS. An increase in the monomer mole fraction of MMA increased the number of polymer particles, while the high monomer mole fraction of MMA failed to stabilize the dispersion of particles. The polymerization for a monomer ratio of St/MMA = 1/1 could produce monodisperse polymer particles of 33 nm at a surfactant concentration of 1 mM that was higher than its CMC (0.085 mM) but much lower than several ten mM of surfactant concentrations in conventional emulsion polymerization.