Penfold Nicholas J W, Ning Yin, Verstraete Pierre, Smets Johan, Armes Steven P
Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , South Yorkshire S3 7HF , UK . Email:
Procter & Gamble, Eurocor NV/SA , Temselaan 100 , 1853 Strombeek-Bever , Belgium.
Chem Sci. 2016 Dec 1;7(12):6894-6904. doi: 10.1039/c6sc03732a. Epub 2016 Sep 13.
A series of linear cationic diblock copolymer nanoparticles are prepared by polymerization-induced self-assembly (PISA) reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA) using a binary mixture of non-ionic and cationic macromolecular RAFT agents, namely poly(ethylene oxide) (PEO, = 4400 g mol; / = 1.08) and poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) (PQDMA, = 31 800 g mol, / = 1.19). A detailed phase diagram was constructed to determine the maximum amount of PQDMA stabilizer block that could be incorporated while still allowing access to a pure worm copolymer morphology. Aqueous electrophoresis studies indicated that zeta potentials of +35 mV could be achieved for such cationic worms over a wide pH range. Core cross-linked worms were prepared statistical copolymerization of glycidyl methacrylate (GlyMA) with HPMA using a slightly modified PISA formulation, followed by reacting the epoxy groups of the GlyMA residues located within the worm cores with 3-aminopropyl triethoxysilane (APTES), and concomitant hydrolysis/condensation of the pendent silanol groups with the secondary alcohol on the HPMA residues. TEM and DLS studies confirmed that such core cross-linked cationic worms remained colloidally stable when challenged with either excess methanol or a cationic surfactant. These cross-linked cationic worms are shown to be much more effective bridging flocculants for 1.0 μm silica particles at pH 9 than the corresponding linear cationic worms (and also various commercial high molecular weight water-soluble polymers.). Laser diffraction studies indicated silica aggregates of around 25-28 μm diameter when using the former worms but only 3-5 μm diameter when employing the latter worms. Moreover, SEM studies confirmed that the cross-linked worms remained intact after their adsorption onto the silica particles, whereas the much more delicate linear worms underwent fragmentation under the same conditions. Similar results were obtained with 4 μm silica particles.
通过聚合诱导自组装（PISA），使用非离子和阳离子大分子可逆加成-断裂链转移（RAFT）剂的二元混合物，即聚环氧乙烷（PEO，Mn = 4400 g/mol；Đ = 1.08）和聚[2-(甲基丙烯酰氧基)乙基]三甲基氯化铵（PQDMA，Mn = 31800 g/mol，Đ = 1.19），通过甲基丙烯酸2-羟丙酯（HPMA）的可逆加成-断裂链转移（RAFT）水分散聚合制备了一系列线性阳离子双嵌段共聚物纳米颗粒。构建了详细的相图，以确定在仍能获得纯蠕虫状共聚物形态的情况下可以掺入的PQDMA稳定剂嵌段的最大量。水性电泳研究表明，在很宽的pH范围内，此类阳离子蠕虫的ζ电位可达到 +35 mV。使用略有修改的PISA配方，通过甲基丙烯酸缩水甘油酯（GlyMA）与HPMA的统计共聚制备核交联蠕虫，然后使位于蠕虫核内的GlyMA残基的环氧基团与3-氨丙基三乙氧基硅烷（APTES）反应，并使侧链硅醇基团与HPMA残基上的仲醇发生伴随水解/缩合反应。透射电子显微镜（TEM）和动态光散射（DLS）研究证实，当用过量甲醇或阳离子表面活性剂挑战时，此类核交联阳离子蠕虫保持胶体稳定。结果表明，在pH 9时，这些交联阳离子蠕虫作为1.0 μm二氧化硅颗粒的架桥絮凝剂比相应的线性阳离子蠕虫（以及各种商业高分子量水溶性聚合物）更有效。激光衍射研究表明，使用前者蠕虫时二氧化硅聚集体直径约为25 - 28 μm，而使用后者蠕虫时仅为3 - 5 μm。此外，扫描电子显微镜（SEM）研究证实，交联蠕虫吸附到二氧化硅颗粒上后保持完整，而更为脆弱的线性蠕虫在相同条件下会发生破碎。对于4 μm二氧化硅颗粒也获得了类似结果。
