Miniemulsion Copolymerization Research Articles

Application of Network Dimension Theory to the Kinetics of Nanogel Formation in Miniemulsion Vinyl/Divinyl Copolymerization: Free‐Radical and Living Polymerization

AbstractIn vinyl/divinyl copolymerization, a crosslink is formed by the reaction between an active center and a pendant double bond. When both the active center and the pendant double bond are located within the same polymer molecule, the cyclization occurs, which is ineffective for growth in molecular weight. In the present model, the network dimension theory is applied to estimate the mean‐square radius of gyration for the growing polymer molecule, which is used to account for the enrichment effect of pendant double bonds around the active center for the cyclization reaction. The model is applied to the miniemulsion copolymerization, and both conventional free‐radical polymerization and ideal living polymerization are considered. Some of important characteristics of network architecture formed in these two types of polymerization mechanisms that cannot be predicted based on the classical chemical kinetics can be reproduced by the model, such unique characteristics as the pendant double bonds are consumed from the beginning of polymerization in the conventional free‐radical polymerization but not so in the living polymerization. The present model provides useful insights into the size and structural dependent network formation kinetics without relying on the lattice model.This article is protected by copyright. All rights reserved

Emulsion polymerized styrene acrylic/nanocellulose composite coating to improve the strength and hydrophobicity of kraft paper

Improving the mechanical and water repelling property of kraft paper will extend its use for packaging application. In this work, we developed a cellulose nanofiber (CNF)-based colloidal polymer nanocomposite that was used as coating for improving those properties of kraft paper. In this case, the polymer latex was obtained by the mini-emulsion copolymerization of styrene (St), 2-ethyl hexyl acrylate (EHA) initiated by ammonium persulfate. The CNFs were incorporated into the styrene-acrylic copolymer matrix by the in-situ polymerization and ex-situ mixing process keeping the CNF concentration up to 1.0 wt%. All the latexes showed particle size below 100 nm and excellent colloidal stability (Zeta potential > −32 mV) for several months. The nanocomposite films showed improved mechanical properties (tensile strength upto 7.8 MPa, elongation upto 1096 %) than the pristine copolymer. The in-situ prepared nanocomposite at 1.0 wt% CNF showed the highest storage modulus. The latex-coated kraft paper showed improved tensile index (31.0–45.1 Nm/g) compared to the uncoated paper (20.3 Nm/g) and also high hydrophobicity (water contact angle ∼120°) for the ex-situ prepared nanocomposites. The results are quite promising to develop paper-based packaging materials using nanocellulose in combination with synthetic polymers.

Photochromic polymer nanoparticles as highly efficient anticounterfeiting nanoinks for development of photo-switchable encoded tags

• Synthesis of colloidal nanoparticles with different polarity and particle size, • Preparation of spiropyran-containing photochromic colloidal nanoparticles, • Effect of polarity on the fluorescence emision and photochromism of colloidal nanoparticles, • Development of the photochromic colloidal nanoparticles as anticounterfeiting nanoinks, • Application of the smart nanoinks for encrypting security documents. Dual photochromic and photoluminescent latex nanoparticles were synthesized to develop innovative anticounterfeiting nanoinks with applications in encryption technology. The colloidal nanoparticles bearing hydroxyl groups were resulted from semi-continuous miniemulsion copolymerization of 2-hydroxyethyl methacrylate and methyl methacrylate. Investigation of the particle size determination and microscopic analysis results demonstrated spherical morphologies for the latex nanoparticles with a mean size of about 80 nm and narrow size distribution. Modification of the polymer nanoparticles with hydroxyl functional groups led to the formation of a high level of hydrogen bonding between the hydroxyl groups and spiropyran chromophore, which is an advantage in the preparation of security anticounterfeiting nanoinks. In addition, optical analysis of the photochromic latex samples showed various UV-vis spectra, fluorescence emission, kinetics of isomerization, and photo-fatigue resistance depending on different amounts of the polar monomers. Further investigations on optical properties exhibited that reducing the size of the colloidal samples can affect their photoluminescence characteristics. This is an efficient way to provide remarkable photoreversible anticounterfeiting inks for different applications, such as printed photo-marking, rewritable handwriting patterns, security encoded tags, and labeling.

Environmentally-friendly short-chain perfluoropolyether polyacrylates emulsion films for high water barrier coating applications

Water-based protective coatings have gained wide popularity because of their low toxicity and volatile organic compounds (VOCs) emissions. However, improving water barrier performance is a significant challenge. An environmentally friendly short-chain perfluoropolyether carboxylic acid (PFPE-MMA) material has been synthesized in this study, and a series of PFPE-based polyacrylates were prepared using RAFT miniemulsion copolymerization. The impact of PFPE chains and crystalline stearyl methacrylate (SMA) on the wettability of copolymer latex films and their use in protective coatings were studied. Based on the surface and bulk morphology of latex films, the addition of SMA to PFPE-based polyacrylates promoted PFPE chains to migrate toward the air/film interface, leading to exceptional wettability and water resistance through the matrix, resulting in remarkable water barrier properties. After 192 h, the water absorption ratio of 25% PFPE-7% SMA latex film was 3.98%, while that of 25% PFPE latex film was 6.03%. Not only are PFPE-based polyacrylates excellent protective materials with potential applications, but they are also an effective preparation strategy for improving the high barrier property in waterborne protective coatings.

Biosourced Polymeric Emulsifiers for Miniemulsion Copolymerization of Myrcene and Styrene: Toward Biobased Waterborne Latex as Pickering Emulsion Stabilizer.

Biobased waterborne latexes were synthesized by miniemulsion radical copolymerization of a biosourced β-myrcene (My) terpenic monomer and styrene (S). Biobased amphiphilic copolymers were designed to act as stabilizers of the initial monomer droplets and the polymer colloids dispersed in the water phase. Two types of hydrophilic polymer backbones were hydrophobically modified by terpene molecules to synthesize two series of amphiphilic copolymers with various degrees of substitution. The first series consists of poly(acrylic acid) modified with tetrahydrogeraniol moieties (PAA-g-THG) and the second series is based on the polysaccharide carboxymethylpullulan amino-functionalized with dihydromyrcenol moieties (CMP-g-(NH-DHM)). The produced waterborne latexes with diameters between 160 and 300 nm and were composed of polymers with varying glass transition temperatures (Tg,PMy = -60 °C, Tg,P(My-co-S) = -14 °C, Tg,PS = 105 °C) depending on the molar fraction of biobased β-myrcene (fMy,0 = 0, 0.43, or 1). The latexes successfully stabilized dodecane-in-water and water-in-dodecane emulsions for months at all compositions. The waterborne latexes composed of low Tg poly(β-myrcene) caused interesting different behavior during drying of the emulsions compared to polystyrene latexes.

Investigation of the water barrier properties of graft copolymer latex films of acrylate and poly(dimethylsiloxane) macromonomers synthesized by RAFT miniemulsion polymerization

It is challenging to improve the water barrier performance for waterborne protective coating. We synthesized a series of acrylic-polydimethylsiloxane (PDMS) graft copolymer latexes p(MMA-co-BA)-g-PDMS) with high PDMS content of up to 50%, which were considered as bottle-brush polymers using reversible addition-fragmentation chain transfer mediated “macromonomer” miniemulsion copolymerization. We investigated the effect of PDMS side chains on the water barrier performance of graft copolymer latex film derived from these particles and their utilization in anti-corrosion coatings. The water contact angle reaches 117° for films cast from aqueous dispersions of graft copolymers with 50% PDMS, which indicates that their surface is significantly enriched with PDMS. The increase in PDMS content has a highly positive effect on the water barrier performance. Differential scanning calorimeter (DSC) on copolymer films after soaking in water indicates that the high PDMS content (50% PDMS) graft copolymer has only freezing bound water in films. Electrochemical impedance spectra tests showed that the graft copolymer exhibited a significant improvement in corrosion resistance over the control polyacrylate sample without PDMS. Furthermore, transmission electron microscopy observations reveal that the PDMS phase changes from a spherical domain texture to a bicontinuous gyroid texture in the bulk of latex films with the increasing PDMS content, which makes them suitable as waterborne anti-corrosion silicone coatings.

Novel self-cross-linking fluorinated polyacrylate latex films with short chain perfluoroalkyl group: Surface free energy and surface reorganization

Fluorinated polymers with chains longer than six carbon perfluoroalkyl groups have been banned due to their detrimental effects on environment and human health, and other alternatives are of increasing concerns. In this study, an environmentally friendly self-cross-linking fluorinated polyacrylate hybrid latex with short perfluoroalkyl group has been synthesized from the monomers of (2-(perfluorobutyl) ethyl acrylate (PFHEA, four carbon atoms), stearyl acrylate (SA)), methyl methacylate (MMA), butyl acylate (BA), octamethylclotetrasiloxane (D4) and cross-linking agent (vinyltriethoxysilane, VTES) by a simple one-step miniemulsion copolymerization. The wetting properties, surface energy and surface reorganization, microstructure, and mechanical properties of the synthesized hybrid latex films were systematically investigated. Results showed that the stable low surface energy of these synthesized self-cross-linking fluorinated polyacrylate hybrid latex films with short chain perfluoroalkyl group were attributed to the synergetic effect of crystal side chains of stearyl pendant groups and cross-linking structure effectively restricted the reconstruction of short fluorine chains. Furthermore, the optimum VTES content was 5 wt%, the obtained latex film exhibited excellent mechanical properties. We envision that this new class of self-crosslinking fluorinated polymer latexes has great potential as nonwetting coatings.

Dynamic Photochromic Polymer Nanoparticles Based on Matrix-Dependent Förster Resonance Energy Transfer and Aggregation-Induced Emission Properties.

Dynamic color-tunable fluorescent materials are sought-after materials in many applications. Here, we report a polymeric matrix-regulated fluorescence strategy via synergistically modulating aggregation-induced emission (AIE) properties and the Förster resonance energy transfer (FRET) process, which leads to tunable dynamic variation of color and photoluminescence (PL) intensity of fluorescent polymeric nanoparticles (FRET-PNPs) driven by photoirradiation. The FRET-PNPs were prepared via a facile one-pot miniemulsion copolymerization with the tetraphenyletheyl (TPE) and spiropyran (SP) units chemically bonded to the polymer matrix. The FRET-PNPs exhibited dynamic variation of fluorescence properties (colors and PL intensity) under photoirradiation on the timescale of minutes. The variation of the polymer matrix composition could deliberately influence the AIE property of TPE units and the isomerization process of SP to merocyanine units, which further affect the FRET efficiency of FRET-PNPs and, eventually, lead to versatile dynamic fluorescence variation. The dynamic fluorescence property as well as the excellent processability and film formation ability of FRET-PNPs allowed for diverse applications, such as warning labels, dynamic decorative painting, and multiple information encryption. Without sophisticated molecular design or tedious preparation processes, a new perspective for the design, fabrication, and performance optimization of fluorescent nanomaterials for innovative applications was proposed.

Application of Magnetic Nanoparticles Coated with Crosslinked Zwitterionic Poly(ionic liquid)s for the Extraction of Oligonucleotides.

Magnetic nanoparticles coated with zwitterionic poly(ionic liquid)s were applied for dispersive solid-phase extraction of oligonucleotides. The materials were synthesized by miniemulsion copolymerization of ionic liquids and divinylbenzene on magnetic nanoparticles. The functional monomers contain a positively charged imidazolium ring and one of the anionic groups: derivatives of acetate, malonate, or butyl sulfonate ions. Adsorption of unmodified DNA oligonucleotide on obtained materials was possible in ion-exchange (IE) and hydrophilic interactions (HI) mode. The adsorption in IE was possible at low pH and was almost complete. The adsorption in HI mode required the usage of appropriate addition of organic solvent but did not provide full adsorption. Studies on the desorption of the analytes included determining the impact of ammonium acetate concentration and pH and organic solvents addition on the recovery. The material containing acetic fragments as an anionic group was selected for the final procedure with the use of 10 mM ammonium acetate (pH = 9.5)/methanol (50/50, v/v) as an elution solution. The magnetic dispersive solid-phase extraction procedure was tested for the oligonucleotides with various modifications and lengths. Moreover, it was applied to extract DNA oligonucleotide and its synthetic metabolites from enriched human plasma without any pre-purification, with recoveries greater than 80%.

In situ encapsulation of praziquantel through methyl methacrylate/diethylaminoethyl methacrylate and MMA/DMAEMA miniemulsion copolymerizations in presence of distinct ionic surfactants

AbstractSchistosomiasis is a neglected tropical disease that affects primarily the poorest and most vulnerable populations. Although praziquantel (PZQ) is the drug used most frequently for treatment of schistosomiasis, PZQ presents unpleasant bitter taste and low solubility in water, which prejudice the implementation of pediatric treatments. For this reason, the main purpose of the present work was the production of stable nanoparticles loaded with PZQ through in situ miniemulsion copolymerizations of methyl methacrylate (MMA) with diethylaminoethyl methacrylate (DEAEMA) or dimethylaminoethyl methacrylate (DMAEMA). Due to the cationic nature of the comonomers, the use of different ionic surfactants was also investigated. Nanoparticles with narrow particle size distributions, characteristic average diameters ranging from 50 nm to 110 nm, and loaded with 20 wt% of PZQ were manufactured successfully PZQ encapsulation efficiencies were higher than 97 wt% and PZQ was homogeneously dispersed in the final polymer matrix. Finally, the use of a cationic surfactant with DEAEMA cationic comonomer led to more stable latexes because of the high absolute value of the zeta potential.

High pressure semibatch emulsion and miniemulsion copolymerization of vinyl acetate and ethylene

AbstractThis study presents the experimental study of semibatch emulsion and miniemulsion copolymerization of vinyl acetate (VAc) and ethylene to vinyl acetate‐ethylene (VAE) copolymer at 60°C and 80–300 psig. In the miniemulsion copolymerization, a water‐soluble initiator (K2S2O8) is used and VAc miniemulsion is prepared in presence of surfactant and cosurfactant using a sonicator or a high‐shear homogenizer. Then, ethylene gas is supplied to the reactor at constant partial pressure. In a miniemulsion process, the mass transfer limitations of VAc from monomer droplets to the aqueous phase, and to micelles or polymer latex particles that are present in conventional macro‐emulsion polymerization can be eliminated and the transfer of ethylene dissolved in the aqueous phase to the miniemulsion droplets is the major ethylene transport process for the polymerization. The experimental data show that the amount of ethylene incorporation into the copolymer is higher in miniemulsion polymerization than in emulsion polymerization. The ethylene pressure has been found to have a strong impact on the ethylene incorporation into the copolymer phase in both emulsion and miniemulsion copolymerizations but the increase is more pronounced in miniemulsion case. The VAE copolymer latex particles prepared by miniemulsion polymerization exhibited higher storage stability than those prepared by macro‐emulsion polymerization.

Preparation of Covalent and Solvent-resistance Colored Latex Particles and Its Application on Cotton Fabric

Conventional colored latex particles have poor solvent resistance due to the absence of chemical bonds between the dye and polymer component, resulting in staining and greatly restricting its application. In this research, the disperse dye was chemically bonded to the polymer to prepare covalent and solvent-resistance colored latex particles. Firstly, C.I. Disperse Red 60, as a common disperse dye in industry, was modified by acryloyl chloride (amidation reaction) for the purpose of introducing the C=C bonds. The structure of modified C.I. Disperse Red 60 was confirmed by 1HNMR, FTIR and elemental analysis and its spectral property was also evaluated. Then the covalent colored latex particles were synthesized via miniemulsion copolymerization of styrene (St) and ethyl acrylate (EA) in presence of modified C.I. Disperse Red 60 monomer. Results of FTIR, TG, DSC and TEM indicated that the covalent colored latex particles were successfully prepared. By using UV-spectroscopy, the solvent resistance of the colored latex membranes in petroleum ether, hexane, cyclohexane, and ethanol was monitored, respectively. Slight change of the absorption was detected for 10 days, which verified the excellent solvent resistance of covalent colored latex membranes. Finally, the prepared colored latex particles were applied on cotton printing in the absence of binder. The results showed that the colored latex particles printed fabric had superior rubbing fastness and soft hand feel.

A highly tough and ultralow friction resin nanocomposite with crosslinkable polymer-encapsulated nanoparticles

A resin nanocomposite embedded by encapsulated nanoparticles with exceptional mechanical and lubrication properties is reported. The functional encapsulated nanoparticles, synthesized by miniemulsion co-polymerization of methyl methacrylate with n-butyl acrylate, styrene and glycidyl methacrylate, had tunable glass transition temperatures and surface reactive glycidyl groups. The as-synthesized nanoparticles with controlled size, shell component and surface function, impacted a nanocomposite with the high toughness and strength as well as ultralow friction properties by their covalent crosslinking with the matrix and the formation of thin boundary lubricant film. Remarkably, the optimal toughness and strength of the nanocomposite with encapsulated nanoparticles achieved 3.8 and 1.5 times those of the counterpart with encapsulated microparticles, respectively. The nanocomposite incorporated with as-synthesized nanoparticles exhibited an ultralow coefficient of friction (COF) and a wear rate of 0.027 and 8.0 × 10−7 mm3/Nm, which were only 3.9% and 0.6% those of the matrix, respectively. The developed robust mechanical and ultralow friction resin nanocomposite from crosslinkable and flexible polymer-encapsulated nanoparticles is highly expected for engineering applications.

Dextran-covered pH-sensitive oily core nanocapsules produced by interfacial Reversible Addition-Fragmentation chain transfer miniemulsion polymerization

Aiming to prepare oily core pH-sensitive nanocapsules (NCs) for anticancer drugs delivery, the use of a dextran-based transurf (DexN3-τCTAγ) as both stabilizer and macromolecular chain transfer agent in methyl methacrylate/2-(diethylamino)ethyl methacrylate (MMA/DEAEMA) miniemulsion copolymerization was investigated. NCs of about 195 nm with an oily-core of Miglyol 810 (M810) and a dextran coverage covalently linked to the poly(MMA-co-DEAEMA) intern shell have been obtained. Compared to the non-sensitive PMMA-based NCs (prepared in a similar way), these novel objects were shown to swell in acidic media and to trigger Coumarin 1 release in physiological relevant pH range. As a starting point of NCs biological effects, cytotoxicity and NCs-proteins interactions studies were performed with both PMMA and poly(MMA-co-DEAEMA)-based NCs. Finally, free azide functions from dextran-based coverage were successfully exploited to attach fluorescent model dyes to NCs surface. The overall results suggest that this novel NCs platform could be potentially used as drug nanocarriers for intravenous injection.

Towards white-light emission of fluorescent polymeric nanoparticles with a single luminogen possessing AIE and TICT properties

White-light-emitting AIE-PNPs were facilely and efficiently prepared through miniemulsion copolymerization by using an AIE luminogen with twisted intramolecular charge transfer properties as a single emitting component.

110th Anniversary: Model-Guided Preparation of Copolymer Sequence Distributions through Programmed Semibatch RAFT Mini-Emulsion Styrene/Butyl Acrylate Copolymerization

The tactics of targeting copolymer composition (CC) and molecular weight (MW) via semibatch controlled radical polymerization (CRP) have been extensively studied. However, little effort is made to target copolymer sequence length (CSL) and its triad sequence, which are among the key microstructures determining material properties of the copolymers. This work presents a method to design and synthesize targeted CSL and copolymer triads in a reversible addition–fragmentation chain transfer radical mini-emulsion copolymerization system (RAFT) through a semibatch chain and sequence model coupled with Alfrey Mayo model. The kinetic model was first derived and correlated with experimental results of the batch St/BA copolymerizations. The semibatch RAFT model was then employed to calculate the feed-rate to target CSL and their triads. St/BA copolymers with different uniform CSLs and their triads are synthesized through the programmed semibatch RAFT mini-emulsion copolymerization processes.

Miniemulsion RAFT Copolymerization of MMA with Acrylic Acid and Methacrylic Acid and Bioconjugation with BSA.

Polymerization through reversible addition-fragmentation chain-transfer (RAFT) polymerization has been extensively employed for the production of polymers with controlled molar mass, complex architectures and copolymer composition distributions intended for biomedical and pharmaceutical applications. In the present work, RAFT miniemulsion copolymerizations of methyl methacrylate with acrylic acid and methacrylic acid were conducted to prepare hydrophilic polymer nanoparticles and compare cell uptake results after bioconjugation with bovine serum albumin (BSA), used as a model biomolecule. Obtained results indicate that the RAFT agent 2-cyano-propyl-dithiobenzoate allowed for successful free radical controlled methyl methacrylate copolymerizations and performed better when methacrylic acid was used as comonomer. Results also indicate that poly(methyl methacrylate-co-methacrylic acid) nanoparticles prepared by RAFT copolymerization and bioconjugated with BSA were exceptionally well accepted by cells, when compared to the other produced polymer nanoparticles because cellular uptake levels were much higher for particles prepared in presence of methacrylic acid, which can probably be associated to its high hydrophilicity.

RAFT mediated miniemulsion copolymerization of ethylene and BMA and their non-isothermal model-free kinetic analysis

Miniemulsion copolymerization of ethylene and butyl methacrylate (BMA) was carried out at 60 °C using 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid as the reversible addition fragmentation chain transfer (RAFT) agent, sodium dodecyl sulphate as emulsifier and potassium per sulphate as free radical initiator under extremely low ethylene feed pressure of 5–20 bar. In the absence of a co-stabilizer, very stable emulsion was obtained, wherein the RAFT agent acted both as the chain transfer agent and as the co-stabilizer. FT-IR as well as NMR analysis established the formation of poly(ethylene-co-BMA) copolymer nanoparticles. The SEM analysis was used to study the morphological behaviour of poly(ethylene-co-BMA) copolymer nanoparticles. DLS analysis confirmed that the particle diameter Zavg of copolymer nanoparticles is in the range 100–140 nm and confirmed miniemulsion polymerization. In order to establish the stability of copolymers against thermal degradation, the kinetics and mechanism of thermal degradation of copolymers were investigated by thermogravimetric analysis. Thermogravimertic analysis established that thermal decomposition of poly(ethylene-co-BMA) copolymer nanoparticles occurred in the range 250–450 °C. This range is lower than the decomposition temperature of neat polyethylene (350–580 °C). Kinetic parameters were determined according to the model-free approaches of Friedman and Flynn–Wall–Ozawa. The multivariate nonlinear regression analysis was performed to determine the kinetic model and the corresponding kinetic triplets.

Coupled stochastic simulation of the chain length and particle size distribution in miniemulsion radical copolymerization of styrene and N-vinylcaprolactam

Kinetic Monte Carlo modeling is applied for the coupled simulation of the chain length and particle size distribution in isothermal batch miniemulsion copolymerization of styrene and N-vinylcaprolactam.

Tuning photosensitized singlet oxygen production from microgels synthesized by polymerization in aqueous dispersed media

Miniemulsion copolymerization of vinyl acetate, N-vinylcaprolactam, vinyl benzyl Rose Bengal and divinyl adipate to synthesize switchable photosensitizer-grafted polymer colloids for interfacial photooxygenation reactions.