Synthesis of Silica-polymer Hybrid Particles Via Controlled Radical Polymerization in Aqueous Dispersed Media

Synthesis of Silica-polymer Hybrid Particles Via Controlled Radical Polymerization in Aqueous Dispersed Media

Author: Xiaoguang Qiao

Publisher:

Published: 2013

Total Pages: 0

ISBN-13:

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Water-soluble brush-type polymers composed of poly(ethylene)oxide methacrylate (PEOMA) units with PEO side groups of various chain lengths (Mn = 300 and 950 g mol-1) or of PEOMA300 with methacrylic acid (MAA) were synthesized by nitroxide-mediated polymerization using an alkoxyamine initiator (BlocBuilder®) and SG1 nitroxide in the presence of a low amount of styrene. The PEOMA300-MAA based copolymers showed a dual temperature/pH response. The two series of macroalkoxyamines were used in aqueous emulsion copolymerization of nbutyl methacrylate and styrene leading to the formation of particles composed of amphiphilic block copolymers through polymerization-induced self-assembly, in both the absence and presence of silica. The experiments performed in the absence of silica particles resulted in the formation of sterically or electrosterically stabilized latexes. The polymerization exhibited all the features of a controlled system with however the presence of a small proportion of dead chains. The effect of pH value, ionic strength and type and concentration of the macroalkoxyamine initiator on polymerization kinetics and latex morphologies was investigated. Depending on the reaction conditions, spherical particles, vesicles or nanofibers were successfully prepared. The PEO-based macroalkoxyamines were shown to adsorb on the silica surface via hydrogen bond interaction between PEO and the silanol groups. This enabled block copolymers to be generated in situ on the silica surface leading to hybrid particles with snowman, raspberry, daisy, core-shell, “tadpole-” and “centipede-” like morphologies depending on the silica particle size, pH value and type of macroinitiator.


Fabrication of Anisotropic Polymer Colloid Particles

Fabrication of Anisotropic Polymer Colloid Particles

Author: Attyah Alzhrani

Publisher:

Published: 2011

Total Pages:

ISBN-13:

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The fabrication of complex colloidal particles with anisotropic "patchy" e.g. Januslike, morphology will be studied. Known approaches towards "Janus particles" focus mostly on the micron-sized domain, with common fabrication routes based on monolayer modification or microfluidic production (restricts scale-up). We operate in the submicron regime (typically 100-500 nm) and use scalable emulsion polymerization strategies, in combination with entropic phase separation of swollen cross-linked latex particles and living radical polymerization, i.e. SET-LRP, to prepare our "patchy" amphiphilic particles. In this research, various Cross-linked densities (typically from 1 - 8wt%) poly(styrene) latexes (typically 100-500 nm) functionalized with tert-bromine functional groups, by batch or shot addition of (2-methacryloxyethyl -2- bromoisobutyrate) made via soap-free emulsion polymerization used as the precursor particles. Two synthetic pathways were investigated to make the targeted hairy Janus Particles. Approach one: in which we carried out the domain formation step prior to the fabrication of the polymer brushes, We found out that the effective synthetic way to make Janus hairy dumbbell particles in a reproducible manner is to start the synthesis with light cross-linked density of (1.9 to 3.0 wt% DVB) precursor poly(styrene) latex particles (150-250 nm diameter) made by shot addition method. The direct entropic phase separation from these latex particles leads to the formation of only one new domain with dumbbell shape morphology, when the swelling ratio used between monomer and latex is between 2.0 and 4.0, and with low DVB concentration in the swelling monomer (between 0.15-1.0wt%) using AIBN as initiator. Formation of hydrophilic polymer brushes by SET-LRP resulted in targeted hairy Janus particles with sub-micrometer diameter, in a reproducible manner. The length of the polymer brushes can be controlled by addition of water soluble ATRP initiator to produce shorter polymer brushes. The rate of SET-LRP was ultrafast and the rate can be reduced by addition of deactivator CuBr2. The second approach: water-soluble polymer brushes were grafted onto the surface of latex particles by SET-LRP. These "hairy" cross-linked colloids were swollen with additional monomers and initiator. Elevation of temperature causes entropic phase separation inducing new domains, which were polymerized. This approach leads to mainly popcorn and raspberry particles with some limited cases that are able to make hairy Janus Particles with non reproducible manner. The obtained complex particles show some interesting application such as a stabilization agent for Carbon Nanotubes (CNTs) in aqueous medium, Pickering emulsion stabilizer, and they self assembled upon addition of dilute electrolyte solution.


Polymeric Dispersions: Principles and Applications

Polymeric Dispersions: Principles and Applications

Author: J.M. Asua

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 571

ISBN-13: 9401155127

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A comprehensive and up to date survey of the science and technology of polymeric dispersions. The book discusses the kinetics and mechanisms of polymerization in dispersed media, examines the processes controlling particle morphology, presents both off-line and on-line methods for the characterization of polymer colloids, considers reactor engineering and control, and covers a wide variety of applications, such as latex paint formulations, encapsulation of inorganic particles, reactive latexes, adhesives, paper coating, and biomedical and pharmaceutical applications. Audience: A valuable resource for scientists and engineers, academic and industrial, who are involved in the manufacture or application of polymeric dispersions.


Polymer Particles

Polymer Particles

Author: Masayoshi Okubo

Publisher: Springer Science & Business Media

Published: 2005-02-10

Total Pages: 388

ISBN-13: 9783540229230

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In this special volume on polymer particles, recent trends and developments in the synthesis of nano- to micron-sized polymer particles by radical polymerization (Emulsion, Miniemulsion, Microemulsion, and Dispersion Polymerizations) of vinyl monomers in environmentally friendly heterogeneous aqueous and supercritical carbon dioxide fluid media are reviewed by prominent worldwide researchers. In addition to the important challenges and possibilities with regards to design and preparation of functionalized polymer particles of controlled size, the topics described are of great current interest due to the increased awareness of environmental issues.


Synthesis of Novel Zwitterionic Polymers

Synthesis of Novel Zwitterionic Polymers

Author: Matthew Skinner

Publisher:

Published: 2018

Total Pages:

ISBN-13:

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This dissertation describes the synthesis, characterization, and investigation of novel zwitterionic polymers containing phosphorylcholine (PC), sulfobetaine (SB), and functional choline phosphate (CP) zwitterions for use as surfactants, self-assembled nanomaterials, and therapeutics. Facile, reproducible, and modular chemistries were utilized for incorporating zwitterions into a range of polymer backbones, and strategies were developed for overcoming difficult challenges encountered in zwitterionic polymer synthesis, especially related to the varying solubility of zwitterions, hydrophobic polymers, and functional comonomers. Synthetic strategies utilized in this work give access to well-defined materials with narrow molecular weight distributions, tunable compositions and architectures, and versatile chemical functionality. Chapter 2 describes the synthesis of water-soluble PC- and SB-functionalized siloxane polymers. PC- and SB-siloxane homopolymers and block copolymers were synthesized using thiol-ene 'click' chemistry, and their assembly in water and at oil-water interfaces was investigated. Chapter 3 describes the preparation of zwitterionic block copolymer analogues of commercial Pluronic® surfactants. PC-containing triblock copolymers were prepared with tunable zwitterion content (5-47 mole percent) and relatively narrow molecular weight distributions. These block copolymer amphiphiles readily formed nanoparticles in water and served as novel surfactants. Through the copolymerization of PC- and CP-methacrylate monomers, functional mimics of conventional Pluronic structures became amenable to crosslinking and the successful synthesis of nanomaterials and robust gels. Chapter 4 presents the in vivo evaluation of poly(2-methacryloyloxyethyl phosphorylcholine)-doxorubicin (polyMPC-Dox) prodrugs for treating human ovarian tumors (SKOV-3). In human ovarian tumor-bearing mice, polyMPC-Dox prodrugs with an approximate Dox loading of 19 weight percent accumulated in tumor tissue at twice the level of free Dox, and animals treated with polyMPC-Dox exhibited enhanced survival and retarded tumor growth compared to conventional Dox treatment. Finally, Chapter 5 augments the polyMPC prodrug concept with the development of polymer-temozolomide (TMZ) conjugates intended for glioblastoma treatment. PolyMPC-TMZ prodrugs were prepared by the controlled free radical copolymerization of MPC and novel TMZ-methacrylate monomers, affording copolymers with random and block architectures. Polymer conjugation significantly improved the solution stability of TMZ, and the antitumor activity of polyMPC-TMZ prodrugs was demonstrated in TMZ-sensitive (U87MG) and TMZ-resistant (T98G) glioblastoma cell lines. The impact of drug loading, polymer architecture, and adjuvant co-delivery on the cytotoxicity of polyMPC-TMZ conjugates was investigated.


Polymeric Surfactants

Polymeric Surfactants

Author: Tharwat F. Tadros

Publisher: Walter de Gruyter GmbH & Co KG

Published: 2017-05-08

Total Pages: 301

ISBN-13: 3110487527

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Polymeric Surfactants covers the structure and stability origins of these highly useful surfactants. Adsorption and solution properties in emulsions are discussed based on their underlying thermodynamics and kinetics. Research scientists and Ph.D. students investigating chemistry, chemical engineering and colloidal science will benefit from this text on polymeric surfactants and their value in preparation and stabilization of disperse systems.