Polystyrene-b-[polystyrene-r-poly(acrylic acid)] block-random copolymers are effective stabilizers of emulsion polymerizations but exhibit unusual dispersion behavior, self-assembling with low aggregation numbers or possibly self-folding into single-chain nanoparticles. In emulsion polymerizations stabilized by these block-random copolymers, the total final particle surface area was directly proportional to the stabilizer concentration and was unaffected by kinetically driven processes such as initiation and particle growth rate; this behavior is not explained by any known emulsion polymerization mechanism. A “seeded-coagulative” emulsion polymerization mechanism is proposed, in which particles grow by polymerization and continuous coagulation, conserving total surface area. Mathematical equations for this proposed mechanism fit the experimental data well and explain the observed dependence of particle number on stabilizer concentration (N_p ∼ [S]³) and solids content (N_p ∼ τ^–2). The novel emulsion polymerization mechanism is attributed to the unique properties of the stabilizers used.

中文翻译：

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两亲嵌段-无规共聚物稳定剂：“种子-凝聚”乳液聚合机制

聚苯乙烯-b- [聚苯乙烯-r-聚（丙烯酸）]嵌段无规共聚物是乳液聚合的有效稳定剂，但表现出不寻常的分散行为，具有低聚集数的自组装或可能自折叠成单链纳米颗粒。在由这些嵌段无规共聚物稳定的乳液聚合中，最终颗粒的总表面积与稳定剂浓度成正比，不受引发和颗粒生长速率等动力学驱动过程的影响；这种行为不能用任何已知的乳液聚合机理来解释。提出了一种“种子-凝聚”乳液聚合机理，其中颗粒通过聚合和连续凝聚生长，从而保持总表面积。N _p ∼ [ S ] ³ ) 和固体含量 ( N _p ∼ τ ^–2 )。新颖的乳液聚合机理归因于所用稳定剂的独特性能。