Monodisperse silica particles (SiPs) were surface-modified with a newly designed reversible addition–fragmentation chain transfer (RAFT) agent having a triethoxysilane moiety, 6-(triethoxysilyl) 2-(((methylthio)carbonothioyl)thio)-2-phenylacetate (EHT). Surface-initiated RAFT polymerization of styrene was carried out with the EHT-modified SiPs in the presence of a free RAFT agent. The polymerization proceeded in a living manner, producing SiPs coated with well-defined polystyrene of a target molecular weight with a graft density as high as 0.3 chains/nm2. Similarly, polymerizations of methyl methacrylate (MMA), N-isopropylacrylamide, and n-butyl acrylate were conducted, providing SiPs grafted with concentrated (high-density) polymer brushes. In all examined cases, the hybrid particles were highly dispersible in solvents for graft polymers, without causing any aggregations. Owing to exceptionally high uniformity and perfect dispersibility, these hybrid particles formed two- and three-dimensionally ordered arrays at the air–water interface and in suspension, respectively. In addition to the surface-grafting on SiPs, the versatility of this technique was demonstrated by carrying out surface-initiated RAFT polymerization of styrene from iron oxide nanoparticles modified with EHT.

Surface-initiated atom transfer radical polymerizations (ATRP) from narrowly size-distributed silica nanoparticles (SiNPs) of diameters less than 100 nm were investigated. Two methods were used for the preparation of the SiNP cores: one was the reverse-micelle technique, which gave monodisperse SiNPs of average diameter 55 nm, and the other was the lysine-addition technique, which gave nearly monodisperse SiNPs of average diameter 15 nm. These nanoparticles were surface-modified with a triethoxysilane derivative containing an ATRP-initiating group. The surface-initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator-fixed SiNPs in the presence of a "sacrificial" free initiator. Well-defined poly(methyl methacrylate) (PMMA) brushes of a target molecular weight were successfully grafted with a surface density as high as 0.4-0.8 chains/nm 2 . These core-shell hybrid particles were highly dispersible, without any aggregation, in various solvents for PMMA. Because of the exceptionally high uniformity and perfect dispersibility, these hybrid particles formed two-and threedimensional ordered arrays at the air-water interface and in suspension, respectively.

This article reports an investigation of the photophysical properties and the light- and dark-biocidal activity of two poly(phenyleneethynylene) (PPE)-based conjugated polyelectrolytes (CPEs) bearing cationic imidazolium solubilizing groups. The two polymers feature the same PPE-type backbone, but they differ in the frequency of imidazoliums on the chains: PIM-4 features two imidazolium units on every phenylene repeat, whereas PIM-2 contains two imidazolium units on every other phenylene unit. Both polymers are very soluble in water and polar organic solvents, but their propensity to aggregate in water differs with the density of the imidazolium units. The polymers are highly fluorescent, and they exhibit the amplified quenching effect when exposed to a low concentration of anionic electron-acceptor anthraquinone disulfonate. The CPEs are also quenched by a relatively low concentration of pyrophosphate by an aggregation-induced quenching mechanism. The biocidal activity of the cationic imidazolium CPEs was studied against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria in the dark and under blue-light illumination. Both polymers are effective biocides, exhibiting greater than 3 log kill with 30-60 min of light exposure at concentrations of ≤10 μg mL(-1).