Preparation of Fe_3O_4/PS Magnetic Particles by Dispersion Polymerization

Fe3O4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5. 54 t0 187. 32 μm were obtained by different reaction conditions.Some parameters such as ethanol, PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.

In Situ Synthesis of Branched Block Copolymer Assemblies via RAFT Dispersion Polymerization Using Branched Macro-RAFT Agents

Here,we demonstrate the use of branched macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agents in RAFT dispersion polymerization,to access branched block copolymers as well as well-defined branched block copolymer assemblies.Two types of branched macro-RAFT agents were first synthesized by using either a monofunctional chain transfer monomer or a difunctional chain transfer monomer in RAFT polymerization,and subsequently utilized in RAFT dispersion polymerization.It was found that only branched macro-RAFT agents synthesized from the difunctional chain transfer monomer could lead to colloidally stable assemblies with well-defined morphologies.Reaction conditions including monomer concentration,degree of polymerization (DP) of the core-forming block,and DP of the solvophilic segment on morphologies of branched block copolymer assemblies were investigated in detail.Size exclusion chromatography (SEC) analysis further confirmed the successful formation of branched block copolymers by using branched macro-RAFT agents.This work on the synthesis of branched block copolymer assemblies by RAFT dispersion polymerization offers new opportunities for the rational design of polymer assemblies with well-defined structures.

Effect of Polymer Network Morphology on the Performance of Polymer Dispersed Liquid Crystal (PDLC) Composite Films

The effects of the morphologies of liquid crystal (LC) droplets left in polymer network on the performance of polymer dispersed liquid crystal composite films were investigated.By adjusting the relative content range of the crosslinking and diluents,the morphologies of polymer network can be changed.Therefore,the properties of PDLC composite films with imparity polymer morphologies were obtained by experiments and the finite element simulation.Results of the experimental and finite element simulation showed that the electro-optical properties of PDLC composite films were inversely proportional to the domain size of the polymer network and the mechanical properties were proportional to the domain size of the polymer network.

Principles and Characteristics of Polymerization-Induced Self-Assembly with Various Polymerization Techniques

A chemical reaction that drives a physical polymer selfassembly process,namely,polymerization-induced self-assembly(PISA),combines block copolymer synthesis and nanoparticle formation efficiently at high polymer concentrations.Various nanoparticlemorphologies such as spheres,worms,and vesicles can be prepared readily in polar and nonpolarmedia.PISA has been well developed in combination with reversible addition-fragmentation chain transfer(RAFT)polymerization.Notably,developments with other polymerization methods are also achieved.In this report,first,we discuss the general principles of RAFT-PISA and the nanoparticles generated from this method.Specifically,new insights into polymer nucleation and subsequent morphological evolution are highlighted.Subsequently,PISA formulations that use other polymerization methods[atom transfer radical polymerization(ATRP),nitroxide-mediated polymerization(NMP),ring-opening metathesis polymerization(ROMP),and ring-opening polymerization(ROP)of N-carboxyanhydrides(NCAs)]are summarized in detail.Finally,more exotic PISA formulations are emphasized:these are based on organotelluriummediated living radical polymerization(TERP),living anionic polymerization(LAP),addition-fragmentation chain transfer(AFCT)polymerization,reversible complexation-mediated polymerization(RCMP),and cobalt-mediated radical polymerization(CMRP),or utilize a comonomer that undergoes radical ringopening polymerization(rROP).This reviewis concluded with a perspective on the status and potential of PISA.

Synchronous Synthesis of Polymeric Vesicles with Controllable Size and Low-Polydispersity by Polymerization-Induced Self-Assembly

Comprehensive Summary The size and size distribution of polymeric nanoparticles have great impact on their physicochemical and biological properties.Polymerization-induced self-assembly(PISA)has been demonstrated to be an efficient method to fabricate various polymeric nanoparticles,among which polymeric vesicles have attracted great interest due to their unique hollow structure.

In Situ Synthesis of Block Copolymer Nano-assemblies by Polymerization- induced Self-assembly under Heterogeneous Condition

Controlled synthesis of amphiphilic block copolymer nanoparticles in a convenient way is an important and interest topic in polymer science. In this review, three formulations of polymerization-induced self-assembly to in situ synthesize block copolymer nanoparticles are briefly introduced, which perform by reversible addition-fragmentation chain transfer(RAFT) polymerization under heterogeneous conditions, e.g., aqueous emulsion RAFT polymerization, dispersion RAFT polymerization and especially the recently proposed seeded RAFT polymerization. The latest developments in several selected areas on the synthesis of block copolymer nano-assemblies are highlighted.

Photo-induced fusion of monodisperse polymer microspheres:A novel strategy for constructing topological microsphere clusters with improved stability

The preparation of monodisperse azobenzene(Azo)polymer microspheres by dispersion polymerization was reported.The photo-induced fusion of Azo polymer microspheres was successfully achieved during the process of reversible trans-cistrans photoisomerization of Azo units,and induced various unique“microsphere molecular”clusters or“microsphere polymers”.Encouraged by this interesting phenomenon,microsphere clusters of different topological structures were stabilized by the in situ acetal cross-linking chemistry.The photo-induced fusion polymerization of monodisperse polymer microspheres provides a new strategy for designing photo-responsive clusters and allows for control over the mechanical properties of microspheres with high spatiotemporal resolution.

Preparation of ABA triblock copolymer assemblies through “one-pot” RAFT PISA

Poly(N,N-dimethyl acrylamide)-block-poly(styrene)-block-poly(N,N-dimethyl acrylamide)(PDMAc-bPSt-b-PDMAc)amphiphilic triblock copolymer micro/nano-objects were synthesized through reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of St mediated with poly(N,Ndimethyl acrylamide)trithiocarbonate(PDMAc-TTC-PDMAc)bi-functional macromolecular RAFT agent.It is found that the morphology of the PDMAc-b-PSt-b-PDMAc copolymer micro/nano-objects like spheres,vesicles and vesicle with hexagonally packed hollow hoops(HHHs)wall can be tuned by changing the solvent composition.In addition,vesicles with two sizes(600 nm,264 nm)and vesicles with HHHs features were also synthesized in high solid content systems(30 wt%and 40 wt%,respectively).Besides,as compared with typical AB diblock copolymers(A is the solvophilic,stabilizer block,and B is the solvophobic block),ABA triblock copolymers tend to form higher order morphologies,such as vesicles,under similar conditions.The finding of this study provides a new and robust approach to prepare block copolymer vesicles and other higher order micelles with special structure via PISA.

Passive patterned polymer dispersed liquid crystal transparent display

A patterned polymer dispersed liquid crystal transparent display using one-time UV exposure is demonstrated.The device is fabricated by exposing the cell with a uniform UV light through a mask with selective attenuation of the UV light.The voltage-transmittance response of the device is different for the corresponding regions.Thus,three different states of total scattering,patterned transparent,and total transparent can be realized by controlling the applied voltages.The proposed device used in shutter mode as smart windows and in projected display mode is demonstrated,which shows great potential for smart windows with customized patterns or logos and has potential application in the field of projected transparent displays.