Takashima Atsushi, Maeda Yasushi, Sugihara Shinji
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui910-8507, Japan.
ACS Omega. 2022 Jul 25;7(30):26894-26904. doi: 10.1021/acsomega.2c03440. eCollection 2022 Aug 2.
Polymerization-induced self-assembly (PISA) is a useful formulation for readily obtaining nanoparticles from block copolymers in situ. Reversible addition-fragmentation chain-transfer (RAFT) emulsion polymerization is utilized as one of the PISA formulations. Various factors have so far been investigated for obtaining nonspherical particles via RAFT emulsion polymerization, such as the steric structure of the shell, the glass-transition temperature ( ) of the core-forming block, and the water solubility of the core-forming monomer. This study focuses on core-forming blocks without changing the structure of the shell-forming block. In particular, we elucidate the balance between for the core-forming block and the water solubility of the core monomer. A series of alkyl methacrylates, such as methyl methacrylate (MMA), ethyl methacrylate (EMA), and -propyl methacrylate (PrMA), are emulsion-polymerized in the presence of a poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) macromolecular chain-transfer agent via the RAFT process. The resulting in situ morphology changes to form shapes such as spheres, worms (toroids), and vesicles are systematically investigated. The properties of the core that determine whether a morphological change occurs from spheres are (i) the solubility of the core-forming monomer in water, (ii) the relationship between for the core-forming block and the polymerization temperature, and (iii) the hydrophobic core volume, which changes the packing parameter. These factors allow prediction of the block copolymer morphology produced during RAFT emulsion polymerization of other methacrylates such as -butyl methacrylate (BuMA), tetrahydrofurfuryl methacrylate (THFMA) with physical properties of the homopolymer (poly(tetrahydrofurfuryl methacrylate) (PTHFMA)) between those for poly(MMA) (PMMA) and PBuMA, and 1-adamantyl methacrylate (ADMA) with low monomer solubility in water and high of the homopolymer (PADMA).
聚合诱导自组装（PISA）是一种从嵌段共聚物原位制备纳米颗粒的有效方法。可逆加成-断裂链转移（RAFT）乳液聚合被用作PISA方法之一。迄今为止，人们已经研究了通过RAFT乳液聚合制备非球形颗粒的各种因素，例如壳层的空间结构、成核嵌段的玻璃化转变温度（ ）以及成核单体的水溶性。本研究聚焦于在不改变壳层形成嵌段结构的情况下研究成核嵌段。特别是，我们阐明了成核嵌段的 与核心单体水溶性之间的平衡。一系列甲基丙烯酸烷基酯，如甲基丙烯酸甲酯（MMA）、甲基丙烯酸乙酯（EMA）和甲基丙烯酸丙酯（PrMA），在聚[聚（乙二醇）甲基醚甲基丙烯酸酯]（PPEGMA）大分子链转移剂存在下通过RAFT过程进行乳液聚合。系统地研究了由此产生的原位形态变化，以形成诸如球形、蠕虫状（环形）和囊泡等形状。决定是否从球形发生形态变化的核心性质包括：（i）成核单体在水中的溶解度；（ii）成核嵌段的 与聚合温度之间的关系；（iii）疏水核心体积，其改变了堆积参数。这些因素使得可以预测在其他甲基丙烯酸酯的RAFT乳液聚合过程中产生的嵌段共聚物形态，例如甲基丙烯酸丁酯（BuMA）、甲基丙烯酸四氢糠酯（THFMA），其均聚物（聚（甲基丙烯酸四氢糠酯）（PTHFMA））的物理性质介于聚（MMA）（PMMA）和PBuMA之间，以及甲基丙烯酸1-金刚烷基酯（ADMA），其单体在水中的溶解度低且均聚物（PADMA）的 高。
