We describe a simplified method to synthesize film forming polymer Janus particles by phase separation during RAFT-based free radical emulsion polymerization. Fully crosslinked snowman- or football-shaped polystyrene Janus particles (PSJPs) were first produced in a one-step batch process using amphiphilic triblock macro-RAFT copolymers as stabilizers. Such particles were in turn employed as seeds in a continuous emulsion polymerization in which a monomer mixture of methyl methacrylate (MMA) and butyl acrylate (BA) (1/1 by weight) was constantly injected into the reaction in the presence of a water soluble initiator. The added monomers wetted seed particle surface and their polymerization led to formations of 93-nm film forming single- or two-headed Janus particles. The resulted latex was successfully used to disperse and encapsulate solid calcite extender.

A novel method is demonstrated to encapsulate titanium dioxide pigment using directed polymerization-induced self-assembly (PISA) with reversible addition-fragmentation chain-transfer (RAFT) controlled emulsion polymerization. The polymerization is carried out in a batch process in which both styrene (Sty) and the pigment are emulsified using triblock amphiphilic macro-RAFT copolymers as stabilizers. RAFT-controlled chain growth leads to directed lamellar self-assembly, forming polystyrene (PS) shells' encapsulating pigment particles with 100% efficiency. The pigment resides either at centers of single-void vesicles or within the interior of multivoid vesiculated particles. The presence of complex morphologies such as spherical particles, nanofibers, nanoplatelets, and polymer vesicles confirms the PISA pathway. The process is optimized to preferably produce polymer-vesiculated pigment for use as an enhanced opacifier in water-based paint.

Janus nanoparticles with soft lobes can self-assemble on the surface of solid substrates in aqueous phase and coalesce to form a complete polymer shell encapsulating the entire solid substrate.

RAFT-mediated free-radical emulsion polymerization is successfully used to synthesize polystyrene nanofibers using triblock amphiphilic macro-RAFT copolymers as stabilizers. The polymerization is under RAFT control, producing various morphologies from spherical particles, nanofibers, nanoplatelets, and polymer vesicles. Optimum conditions are established for the synthesis of predominantly negatively charged polymer nanofibers. Superparamagnetic iron oxide nanoparticles (SPION)-decorated nanofibers are formed by simple mixing of the SPIONs with the fibers at an appropriate pH. The composite material has been found to be superparamagnetic and could be aligned under a magnetic field.

The elastic properties and strength upon compression of commercial Ropaque polystyrene hollow particles were investigated by atomic force microscopy (AFM). These particles are commonly used in paints as opacifying agents, as their internal air void effectively scatters light. A sharp AFM tip was used to apply a point load to the particle surface, and increased to probe both the elastic and plastic deformation of the shell, and then further until the shell broke. For small deformations, the deformation increased linearly with applied force. The Young's modulus was calculated by accounting for the effect of the rigid substrate, and compared to the modulus obtained from the Reissner and Hertz models. The minimum stress needed to destroy the integrity of the shell was extracted and found to be smaller than or close to that of silica hollow particles with different shell thickness tested in the literature.

Polymer encapsulation of raw ferrofluids was carried out by free radical emulsion polymerization using macro-RAFT copolymers as stabilizers. The iron oxide cores with positively charged surface at the pH of encapsulation were dispersed in a solution of negatively charged random macro-RAFT copolymer by ultrasonication. Uniform polymer encapsulated super paramagnetic iron oxide nanoparticles (SPIONs) were produced by feeding the mixture of methyl methacrylate (MMA) and n-butyl acrylate (BA) monomers into the dispersion containing water soluble initiator 4,4’-azobis (4-cyanopentanoic acid) (V501). Shell thickness could be controlled by adjusting the amount of coating monomer added. Polymer encapsulation of SPIONs aligned in a magnetic field produced polymer encapsulated SPION rods. Monodispersed sterically stabilized crosslinked polymer encapsulated SPIONs were synthesized using diblock and random macro-RAFT copolymers as stabilizers. Rhodamine labeled SPIONs were found to be non-cytotoxic and suitable for cell labeling.

A robust and simple synthesis of nano-size oblate to dumbbell shaped polymeric anisotropic particles using RAFT mediated emulsion polymerization is presented. The particle synthesis relies on the property that monomer swollen cross-linked polymer seed particles shrink and expel some of the monomer when heated. Thus, upon heating for polymerization, some of the swelling monomer is expelled and subsequently polymerizes to form a bulge on the side of the original crosslinked seed particle. The shape of the bulge, and the degree of contact that the expelled monomer maintains with the original seed particle, is controlled by controlling the wettability of the seed surface by the expelled monomer. Very small monodisperse cross-linked polymer particles are initially prepared by RAFT mediated emulsion polymerization, then swollen with monomer and further polymerized to form anisotropic particles with a long dimension as little as 25 nm. Both the shape of the anisotropic bulge and the polymer composition, of each end of the final Janus nanoparticle can be finely controlled. The surface active properties of the Janus nanoparticles are demonstrated by their ability to contribute as stabilizers and influence particle formation in a surfactant free ab-initio emulsion polymerization. The method provides a simple and reproducible process for the production of Janus colloidal nanoparticles readily achievable in a normal latex plant where batch size would be limited only by the size of the reactor.

In this work, we present a novel platform to synthesize polymeric "raspberry" particles and explore their use to fabricate surfaces with low wettability and high water adhesion, resembling the properties of naturally occurring surfaces such as the rose petal. The raspberry particles were obtained by layer-by-layer self-assembly of 850 nm core polystyrene particles bearing surface carboxylate groups and corona nanoparticles of different sizes and polymers (polystyrene, poly(para-fluorostyrene) or poly(2,3,4,5,6-penta-fluorostyrene), also bearing surface carboxylates), interleaved with positively charged poly(ally amine) hydrochloride. The raspberry particles were then bound together by covalent coupling of the carboxylate groups with the amine groups of the polymeric interlayer. The films produced by drop-casting the raspberry particles exhibited static water contact angles between similar to 135 degrees and similar to 146 degrees, depending on the nature of the corona, hysteresis of similar to 135 degrees and high adhesion of water droplets. Since all particles were synthesized from scratch by surfactant free emulsion polymerization in air and every step of the protocol was performed in water, this platform is up-scalable and environmentally friendly.

ABSTRACT This work describes a versatile method to encapsulate graphene oxide (GO) with polymers using reversible addition‐fragmentation chain transfer (RAFT) mediated emulsion polymerization. A living low molecular weight anionic macro‐RAFT statistical copolymer of sodium styrene sulfonate, acrylic acid, and butyl acrylate (BA) was synthesized using 2‐{[(butylsulfanyl)carbonothioyl] sulfanyl} propanoic acid as the chain transfer agent. GO was dispersed in water by pretreating the surface with poly(allylamine hydrochloride) (PAH), before being stabilized by the addition of the anionic macro‐RAFT copolymer. PAH was used to facilitate the adsorption of the macro‐RAFT copolymer to the GO surface via electrostatic attraction between opposite charges. The dispersed GO sheets were encapsulated with polymer by the free radical emulsion polymerization of methyl methacrylate and BA under starved fed conditions. The polymer shells encapsulating the GO sheets were formed by the chain extension of the adsorbed living macro‐RAFT copolymer. TEM, SEM, FTIR, and AFM were used to confirm the presence of the polymer layer on the surface of the GO. The thickness of the polymer coating can be adjusted by controlling the amount of monomer fed into the system. Partial polymer coatings of the GO could be achieved by varying the amount of PAH. The encapsulated GO was found to be easily dispersed in both aqueous and organic solvents over a range of polarities. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53 , 1413–1421

In this work, successful synthesis of polymer nanorattles containing titanium dioxide pigment particles in the centers of air voids is reported. The method used amphiphilic macro-RAFT copolymers as stabilizers for pigment dispersion and the subsequent encapsulation of the pigment with polymer. The particles were first encapsulated by a water swellable hydrophilic layer, followed by a hard hydrophobic layer. Nanorattles were formed by swelling of hydrophilic polymer layers on the surface of the encapsulated pigment particles in a basic solution at elevated temperature. After swelling, the outer hard polymer shell was crosslinked to improve its strength. Air void sizes of the nanorattles were found to be controlled by swelling time, temperature, and the hydrophilic polymer layer thickness. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 346-352, 2012

We describe a method and conditions or the preparation of monodisperse latex particle dispersions using low molecular-weight, amphiphilic styrene-b-acrylic acid macro-RAFT diblock copolymers as sole stabilizers. The macro-RAFT copolymers are soluble in styrene monomer droplets when the acrylic acid is in its neutral, protonated form, but adsorb irreversibly at the interface between the monomer droplets and the aqueous phase to form an insoluble monolayer when conditions favor deprotonation. Droplets thus stabilized exhibited no coarsening by Ostwald ripening over at least several days. Polymerization yielded a one-to-one correspondence between the size of the initial droplets and the resultant latex particles, consistent with ideal miniemulsion polymerization when the least labile macro-RAFT stabilizer was used. GPC analysis of molecular weights showed that in all cases the polymerization remained under RAFT control. The approach described enables true miniemulsion polymerization to proceed in the absence of both free surfactant and hydrophobic stabilizer.

During a test programme on a modern heavy-duty engine, measurements were made at engine-out and tailpipe of particle number and particulate mass using the draft heavy-duty inter-laboratory correlation exercise guide prepared by the UN-ECE Particle Measurement Programme (PMP) 1 . In addition to the PMP measurements, the elemental carbon content of the particulate matter from this programme was analysed using thermogravimetric analysis of separate filters. The particle number measurement system proved to provide a reliable and repeatable measurement procedure. Test results over a variety of operational cycles showed a reduction in particle numbers of some 3 orders of magnitude. Particle number emissions were of similar magnitude regardless of the test cycle. Background-corrected particulate mass emissions results using the partial flow dilution method showed emissions levels below 5mg/kWh over all the transient cycles tested.

A new method is described, based on living amphipathic random macro-RAFT copolymers, which enables the efficient polymeric encapsulation of both inorganic and organic particulate materials via free-radical polymerization. The mechanism for this new approach is examined in the context of the polymer coating of zirconia- and alumina-coated titanium dioxide particles and its breadth of application demonstrated by the coating of organic phthalocyanine blue pigment particles. The particulate materials were first dispersed in water using a macro-RAFT copolymer as a stabilizer. Monomer and water-soluble initiator were then added to the system, and the monomer polymerized to form the coating. If nucleation of new polymer particles in the aqueous phase was to be avoided, it was found necessary to use a macro-RAFT copolymer that did not form micelles; within this constraint, a broad range of RAFT agents could be used. The macro-RAFT agents used in this work were found not to transfer competitively in the aqueous phase and therefore did not support growth of aqueous-phase polymer. Successful encapsulation of particles was demonstrated by TEM. The process described enables 100% of the particles to be encapsulated with greater than 95% of the polymer finishing up in the polymeric shells around the particles. Moreover, the coating reaction can be carried out at greater than 50% solids in many cases and avoids the agglomeration of particles during the coating step.

High conversion and selectivity can be obtained for the cross-metathesis of 2-butene with triglycerides and unsaturated fatty acid esters derived from natural oils. This can be achieved with remarkably high productive catalyst turnovers using second-generation ruthenium-based olefin metathesis catalysts.

The cross-metathesis of synthetic and natural triglycerides containing unsaturated fatty acids with 2-butene can be achieved with high conversion and excellent productive turnovers. These reactions are catalysed by second-generation ruthenium-based olefin metathesis catalysts and can be conducted at -5 degrees C in liquid 2-butene.