Miniemulsion Polymerization Research Articles

Influence of fluorine incorporation into waterborne acrylic coatings on resulting hydrophobic, thermal stability and drag- reduction properties

Fluorinated polyacrylate copolymers containing various amounts of 1H,1H,2H,2H-perfluorooctyl methacrylate (FA) were synthesized via a miniemulsion polymerization process. The characteristics of latex particles and films were investigated using transmission electron microscopy, dynamic light scattering, attenuated total reflectance Fourier transform infrared spectroscopy, 1H and 19F nuclear magnetic resonance spectroscopy, atomic force microscopy, energy dispersive spectroscopy, water contact angle measurements, and thermogravimetric analysis. The results showed that particle size increased almost linearly with FA content, and the surface hydrophobicity of the films increased with FA content up to 14.6 wt% and then plateaued. As the FA content increased, the surface roughness of the films initially increased and then decreased. The thermal stability of fluorinated polyacrylate was significantly enhanced when a high amount of FA was incorporated into the polymer chains. The fluorinated acrylic copolymer coating also exhibited a significant drag reduction effect, with the maximum drag reduction ratio reaching 12% at a water flow velocity of 0.8 m/s.

Continuous generation of cross-linked polymer nanoparticles employing an ultrasonic microreactor

In this article, a new system employing an ultrasonic microreactor coupled with a tubular reactor is presented for the continuous generation of polymer nanoparticles. The continuous generation of cross-linked polymer nanoparticles utilizing the monomer butyl methacrylate and the cross-linker ethylene glycol dimethacrylate is demonstrated. Firstly, the miniemulsion polymerization of a monomer-in-water miniemulsion is studied in a batch system. Secondly, a coiled tubular reactor is employed for the continuous polymerization of the miniemulsion generated by an ultrasonic microreactor. Finally, the influence of monomer volume fraction and surfactant concentration on the synthesized polymer nanoparticles is studied. Polymer particles in a size range of 50–250 nm are synthesized and a high polymerization conversion is achieved utilizing the system demonstrated in this article.

Dimensions of Large‐Sized Network Polymers Formed in Miniemulsion Polymerization

AbstractThe mean‐square radius of gyration of network polymers can be correlated with the graph diameter, and the fraction d of segments located in the diameter chain is used to investigate the dimensions of large‐sized network polymers whose cycle rank is over 103. A simplified Monte Carlo simulation model for the miniemulsion vinyl/divinyl copolymerization is used for the generation of large‐sized network polymers, assuming the classical chemical kinetics are valid. Both conventional free‐radical polymerization and living polymerization are considered, and the heterogeneity of network architecture is controlled by changing the reactivity ratio of double bond in divinyl monomer with respect to that in vinyl monomer. The network maturity index (NMI) which is the cycle rank per primary chain is used to represent the degree of development of the network architecture. As the NMI increases to be well‐developed, the calibrated d, defined by dc = d/fd where fd is a calibration constant that shows the degree of network heterogeneity, starts to follow the master curve. This characteristic behavior applies regardless of the polymerization mechanism and the heterogeneity of the formed network architecture. Detailed characteristics of the master curve and prospects for application to gel molecules are also discussed.

Encapsulation of ultraviolet filter into cationic polystyrene particles via miniemulsion polymerization with poly(vinyl alcohol)

Encapsulation of ultraviolet filter into cationic polystyrene particles via miniemulsion polymerization with poly(vinyl alcohol)

Injectable On-Demand Pulsatile Drug Delivery Hydrogels Using Alternating Magnetic Field-Triggered Polymer Glass Transitions.

Remote-controlled pulsatile or staged release has significant potential in a wide range of therapeutic treatments. However, most current approaches are hindered by the low resolution between the on- and off-states of drug release and the need for surgical implantation of larger controlled-release devices. Herein, we describe a method that addresses these limitations by combining injectable hydrogels, superparamagnetic iron oxide nanoparticles (SPIONs) that heat when exposed to an alternating magnetic field (AMF), and polymeric nanoparticles with a glass transition temperature (Tg) just above physiological temperature. Miniemulsion polymerization was used to fabricate poly(methyl methacrylate-co-butyl methacrylate) (p(MMA-co-BMA)) nanoparticles loaded with a model hydrophobic drug and tuned to have a Tg value just above physiological temperature (∼43 °C). Co-encapsulation of these drug-loaded nanoparticles with SPIONs inside a carbohydrate-based injectable hydrogel matrix (formed by rapid hydrazone cross-linking chemistry) enables injection and immobilization of the nanoparticles at the target site. Temperature cycling facilitated a 2.5:1 to 6:1 on/off rhodamine release ratio when the nanocomposites were switched between 37 and 45 °C; release was similarly enhanced by exposing the nanocomposite hydrogel to an AMF to drive heating, with enhanced release upon pulsing observed even 1 week after injection. Coupled with the apparent cytocompatibility of all of the nanocomposite components, these injectable nanocomposite hydrogels are promising as minimally invasive but remotely actuated release delivery vehicles capable of complex release kinetics with high on-off resolution.

Biobased latex adhesives from isobornyl methacrylate and plant-oil-based acrylic monomers

A range of cross-linkable latex copolymers with biobased content of up to 90% was synthesized from isobornyl methacrylate combined with acrylic monomers based on high-oleic soybean oil (HO-SBM) or camelina oil (CMM) through miniemulsion polymerization. By varying the HO-SBM and CMM macromolecular fractions, the cross-linking density of the resulting materials can be altered due to differences in the fatty acid profiles of the plant-oil-based monomers. The glass transition temperature of the synthesized copolymers correlates very well with the calculated Flory–Fox values. A higher cross-linking density of the biobased copolymer films leads to a notable growth in the modulus of the materials, while the elongation at break decreases due to more restricted macromolecular mobility. Remarkably, the copolymer with the highest unsaturation degree in the investigated range (based on CMM) shows an increase in both the modulus and elongation at break, due perhaps to extended entanglements of fatty-acid-based side chains. The adhesion performance of the cross-linked biobased copolymers was evaluated by performing shear and peel strength measurements on steel and polypropylene. Based on the obtained results, the unsaturation degree of CMM and HO-SBM (determined by plant oil composition) can be applied as a criterion for adjusting adhesion by choosing plant-oil-based monomers (or their mixtures) with different unsaturation degrees to achieve properties and performance required for specific applications.

Synthesis and characterization of photochromic polyurethane nanoparticles by miniemulsion polymerization

As an organic photochromic material, spiropyran (SP) has attracted extensive attention due to its rapid and reversible color switching under specific wavelength irradiation. However, the molecular packing during SP isomerization and the influence of external solvents lead to unstable photochromic properties, limiting its practical applications. In this study, the novel photochromic polyurethane nanoparticles were prepared by environmentally friendly materials, isophorone diisocyanate (IPDI) and sorbitan fatty acid esters (Span), through one-step miniemulsion polymerization. The nanoparticles exhibit sensitive photochromic process under UV irradiation, and after 20 UV–vis cycles, these nanoparticles retained the initial photochromic properties. Furthermore, the influence of polyurethane polymer matrix structure on the photochromic properties of SP and the decolorization rate of MC→SP isomerization process was investigated. The prepared polyurethane photochromic nanoparticles demonstrated outstanding photochromic performance and showed great potential for applications in UV-resistant fabrics, surface coatings, and photoelectric signal conversion.

Enzyme assisted oxygen tolerance nitroxide-mediated miniemulsion polymerization

Nitroxide-mediated polymerization (NMP) is known to be a simple reversible deactivation radical polymerization (RDRP) method for preparing well defined polymers. In compared with other RDRP methods, NMP was highlighted by the clean and low toxic product which is favorable for some sensitive biological and electronic applications. Here we reported the first case of oxygen tolerance nitroxide-mediated miniemulsion polymerization, by introducing glucose oxidase (GOx) and ascorbic acid (AsAc) to the system. Without degassing treatment, the miniemulsion polymerization can be carried on using alkoxyamine 3-(((2-cyanopropan-2-yl)oxy) (cyclohexyl)amino)-2,2-dimethyl-3-phenylpropanenitrile (Dispolreg 007) as the initiator. The oxygen tolerance NMP miniemulsion exhibited similar living and control behavior to the degassing system, and the chain extension could also be performed without degassing. The characteristics of this enzyme assisted oxygen tolerant heterogeneous NMP may provide exciting new opportunities for increased versatility of NMP polymerization in preparation of polymeric nano-objects.

Manipulation of surface properties and long-term antibacterial performance of composite films via alkyl side chain engineering

Construction of long-term antibacterial surfaces is highly challengeable but of great academic and social significance. Herein, a strategy integrating the foulant-release property with synergistically bactericidal action is designed to endow the surfaces with long-term antibacterial ability. To fulfill this design principle, quaternized fluoropolymer/Ag composite films (FP-Qx/Ag CFs) were conveniently fabricated via sequential miniemulsion polymerization and squeegeeing techniques. The crucial effect of the alkyl chain length of quaternary ammonium (QA) units on the particle properties and antibacterial ability of quaternized fluoropolymer/Ag nanocomposite particles (FP-Qx/Ag NCPs), as well as the surface properties, surface energy, underwater surface reconstruction, and antibacterial ability of FP-Qx/Ag CFs was disclosed. The long-term antibacterial performance of the FP-Qx/Ag CFs against both regular and multi-drug resistant bacteria depended on the alkyl chain length of QA units. The respective role of surface energy and surface rearrangement, as well as the synergistic bactericidal ability of FP-Qx/Ag CFs that could be manipulated by the alkyl chain length of QA units in the long-term antibacterial performance was decoupled to propose a comprehensive long-term antibacterial mechanism. Our work may guide the design of long-term antibacterial surfaces and provide an effective method to manipulate the property and performance of antibacterial surfaces via alkyl side chain engineering.

Centrifugally spun hybrid polyhydroxyalkanoate/dextran nanocapsule fiber matrix for the delivery of hydrophilic payloads

Biopolymeric micro- and nanofibers with active ingredients have gained significant attention for biological applications. However, the incorporation of hydrophilic compounds into hydrophobic matrices via spinning techniques remain rather unexplored. Here we report the incorporation of dextran nanocapsules (Dex-NCs) in centrifugally spun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) fibers for the release of hydrophilic payloads. Inverse miniemulsion polymerization was employed to synthesize hydrophilic Dex-NCs with an average size of 0.25 µm. The Dex-NCs were embedded into PHBHHx via dual solvent centrifugal spinning at 0–7 wt% loading, resulting in beaded fibers with average fiber diameters of 4–6 µm. The effect of Dex-NC loading on the melting and crystallization behavior of PHBHHx was limited, while the strength and stiffness of the hybrid fibers was retained. The elongation of the hybrid fiber mats is reduced with increasing Dex-NC loading, but remains suitable for biological applications. Further, the in vitro release measurements showed a time dependent release of embedded Dex-NCs and the payload from the hybrid fibers. We anticipate this hybrid fiber matrix to be a starting point for the development of non-woven mats for slow release of hydrophilic payloads for biological applications, especially for medical wound dressings.

Paclitaxel release from hollow PMMA nanoparticles: Factors affecting release rate as quantified via dialysis and membrane centrifugation

Despite known limitations, dialysis and centrifugation remain standard methods for quantifying in vitro drug release kinetics. In the context of quantifying drug release from nanoparticles, dialysis uses a membrane to retain nanoparticles whilst drug released from the nanoparticles transfers across the membrane. The present work investigates the use of dialysis and solely for comparison membrane centrifugation for quantitative characterisation of Paclitaxel (PAX) release from hollow poly(methyl methacrylate) (PMMA) nanoparticles (PAX-NPs) synthesised using a simple one-pot miniemulsion polymerisation system. The impact on drug release rate when using GSH to cleave disulphide crosslinked PMMA, the incorporation of methacrylic acid as a co-monomer, and use of a hydrotrope (sodium subsalicylate) for enhanced drug solubility are discussed. Finally, we summarise the limitations of dialysis and membrane centrifugation due to a complex interplay of factors including drug concentration, molecular weight, hydrophobicity, internal to external dialysis volume and partitioning.

Bio-Based Waterborne Poly(Vanillin–Butyl Acrylate)/MXene Coatings for Leather with Desired Warmth Retention and Antibacterial Properties

This study presents a solvent-free, facile synthesis of a bio-based green antibacterial agent and aromatic monomer methacrylated vanillin (MV) using vanillin. The resulting MV not only imparted antibacterial properties to coatings layered on leather, but could also be employed as a green alternative to petroleum-based carcinogen styrene (St). Herein, MV was copolymerized with butyl acrylate (BA) to obtain waterborne bio-based P(MV–BA) miniemulsion via miniemulsion polymerization. Subsequently, MXene nanosheets with excellent photothermal conversion performance and antibacterial properties, were introduced into the P(MV–BA) miniemulsion by ultrasonic dispersion. During the gradual solidification of P(MV–BA)/MXene nanocomposite miniemulsion on the leather surface, MXene gradually migrated to the surface of leather coatings due to the cavitation effect of ultrasonication and amphiphilicity of MXene, which prompted its full exposure to light and bacteria, exerting the maximum photothermal conversion efficiency and significant antibacterial efficacy. In particular, when the dosage of MXene nanosheets was 1.4 wt%, the surface temperature of P(MV–BA)/MXene nanocomposite miniemulsion-coated leather (PML) increased by about 15 °C in an outdoor environment during winter, and the antibacterial rate against Escherichia coli and Staphylococcus aureus was nearly 100% under the simulated sunlight treatment for 30 min. Moreover, the introduction of MXene nanosheets increased the air permeability, water vapor permeability, and thermal stability of these coatings. This study provides a new insight into the preparation of novel, green, and waterborne bio-based nanocomposite coatings for leather, with desired warmth retention and antibacterial properties. It can not only realize zero-carbon heating based on sunlight in winter, reducing the use of fossil fuels and greenhouse gas emissions, but also improve ability to fight off invasion by harmful bacteria, viruses, and other microorganisms.

Selective distribution of silica grafted with crosslinked poly(methyl methacrylate) in poly(methyl methacrylate)/poly (styrene-co-acrylonitrile) blend

The selective distribution of silica nanoparticles(NPs) grafted with crosslinked poly(methyl methacrylate) (PMMA) in PMMA/poly(styrene-co-acrylonitrile) (SAN) blend is investigated by varying the crosslinking degree of grafted PMMA. NPs grafted with highly crosslinked PMMA chains mainly tend to be located in the PMMA-rich domains, while NPs grafted with linear PMMA chains mainly tend to be distributed at the interface of blend matrix. NPs grafted with slightly crosslinked chains are located partially at the interface and partially in the PMMA-rich domains. The deviation between the theoretical predication and actual location of modified NPs may be related with the heterogeneity of miniemulsion polymerization. Furthermore, different location of three modified NPs induced by different grafted chain structure may result in their various compatibilization effects on PMMA/SAN blend. NPs grafted with linear or slightly crosslinked PMMA aggregate at the interface of blend matrix to form the jamming structure and further inhibit completely the domain coarsening.

Durable and rechargeable antimicrobial cotton driven by enhanced UV stability and real-time detection of biocidal factors

In this study, graphene oxide/N-halamine nanocomposite was synthesized through Pickering miniemulsion polymerization, which was then coated on cotton surface. The modified cotton exhibited excellent superhydrophobicity, which could effectively prevent microbial infestation and reduce the probability of hydrolysis of active chlorine, with virtually no active chlorine released in water after 72 h. Deposition of reduced graphene oxide nanosheets endowed cotton with ultraviolet-blocking properties, attributing to enhanced UV adsorption and long UV paths. Moreover, encapsulation of polymeric N-halamine resulted in improved UV stability, thus extending the life of N-halamine-based agents. After 24 h of irradiation, 85 % of original biocidal component (active chlorine content) was retained, and approximately 97 % of initial chlorine could be regenerated. Modified cotton has been proven to be an effective oxidizing material against organic pollutants and a potential antimicrobial substance. Inoculated bacteria were completely killed after 1 and 10 min of contact time, respectively. An innovative and simple scheme for determination of active chlorine content was also devised, and real-time inspection of bactericidal activity could be achieved to assure antimicrobial sustainability. Moreover, this method could be utilized to evaluate hazard classification of microbial contamination in different locations, thus broadening the application scope of N-halamine-based cotton fabrics.

RECENT TRENDS IN DIFFERENT TYPES OF SYNTHETIC HYDROPHILIC POLYMER NANOPARTICLES, METHODS OF SYNTHESIS & THEIR APPLICATIONS

Numerous types of hydrophilic polymer nanoparticles (NPs) have recently become research hotspots because of their ability to dissolve in water and can be adapted with respect to physical, chemical, and biological properties to meet the requirements of different applications. Synthetic hydrophilic polymeric NPs had successfully gained much attention because of their unique physicochemical properties, such as low toxicity, biodegradability, bioavailability, and support material for extensive swelling in water. These synthetic hydrophilic polymers NPs create new opportunities to produce water-soluble polymer types that would be able to imitate the structure and function of biological polymers. Several synthetic hydrophilic polymer NPs that gain high interest recently including poly(N-isopropyl acrylamide) (PNIPAM), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and poly(N-(2-hydroxypropyl) methacrylamide (PHPMA) are reviewed in this paper. Furthermore, various synthesis methods to produce synthetic hydrophilic polymer NPs for instance emulsion polymerization, microemulsion polymerization and inverse miniemulsion polymerization are highlighted, and a brief overview on their recent applications especially in medical applications are also be discussed thoroughly in this review.

How phase transfer increases the number of kinetic regimes from three to seven in nitroxide mediated polymerization of n-butyl acrylate in aqueous miniemulsion

One of the challenges in reversible deactivation radical polymerization (RDRP) in miniemulsion is identifying the optimal average particle size (dp), offering both high reaction rates and excellent control over chain length, branching level and functionality. In this work, a deterministic multi-dimensional Smith-Ewart model is combined with a method of moments model for nitroxide (N-(2-methyl-2-propyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl; SG1) mediated polymerization (NMP) of n-butyl acrylate in miniemulsion. This model accounts for reaction and phase transfer, to showcase for the first time seven instead of three kinetic regimes in a broad dp range from 5 to 300 nm. The reliability of the model prediction is high because of (i) successful model validation under miniemulsion conditions at 385 K; (ii) unique consideration of β-scission, allowing realistic prediction of the livingness; (iii) a validated temperature dependent SG1 partitioning coefficient; and (iv) many kinetic model parameters sourced from independent experimental validation under bulk/solution conditions. Pseudo-bulk kinetics (kinetic regime 1) and a dominance of the segregation effect (kinetic regime 2) are predicted at the highest dp. For decreasing dp, a novel regime 3 emerges in which exit of NMP initiator radicals is dominant. For even lower dp, dominance of free SG1 exit (kinetic regime 4), then dominance of the confined space effect first for NMP initiator radicals (kinetic regime 5), then the same but for free SG1 (kinetic regime 6), and rapid exit-entry dynamics with negligible termination (kinetic regime 7) are obtained. This work demonstrates that advanced population balance models for sustainable multiphase reactive processes can bridge experiment and simulation for improved functional material design.

The Design and Preparation of Antibacterial Polymer Brushes with Phthalocyanine Pigments

Phthalocyanine pigments have many problems in waterborne coating applications because of their low polarity, poor dispersion in water, and easy agglomeration properties. In order to solve these problems, the phthalocyanine pigments were encapsulated with a copolymer of methyl methacrylate (MMA) and butyl acrylate (BA) by a mini-emulsion polymerization method. The pigments are effectively dispersed in water and have good compatibility with the resin. Concerning the bacterial reproduction and growth problem for the waterborne system, the resin-encapsulated phthalocyanine pigments were further grafted with antibacterial polymer poly(N-(2-hydroxyethyl) acrylamide) (PHEAA) on its surface using the photoemulsion polymerization technique. Comprehensive properties, including centrifugal stability and chromaticity change, were studied. The polymer encapsulation improved the centrifugal stability of the pigment. The thermogravimetric results showed that the residual mass of C.I. Pigment Green 7 (52.30%) was higher than that of C.I. Pigment Blue 15:3 (30.06%), and the sublimation fastness of PG7 was higher. The TEM results revealed that the shape of the PG7 after encapsulation and grafting was more regular than that of PB15:3. The L* of the pigment decreased after encapsulation but then increased after further grafting. The phthalocyanine pigment composite latex had good antibacterial properties after the grafting of PHEAA.

Waterborne polymer composites containing hybrid graphene/carbon nanotube filler: Effect of graphene type on properties and performance

AbstractPolymer composites based on graphene/carbon nanotubes (G/CNT) and reduced graphene oxide/carbon nanotubes (rGO/CNT) were synthetized by in‐situ miniemulsion polymerization containing 1 wt% hybrid filler with different ratio of G and CNT (10:1, 1.1, 1:10). From the hybrid aqueous dispersions obtained in that way polymer films were spontaneously formed at ambient conditions by water evaporation. The effect of the type of the graphene filler, G or rGO, on the properties and performance of polymer composites was studied. It was shown that G/CNT based composites presented improved morphology of the film due to better distribution of the filler and more organized structure of the film than that of rGO/CNT composites. The surface of the film was much smoother indicating more deepen filler within the polymer. Consequently, the G/CNT/polymer composites presented one order of magnitude increased Young's moduli and 60% lower water uptake than the neat polymer. Even though rGO/CNT/polymer composites presented also improved mechanical resistance, their water resistance was compromised probably due to the presence of hydrophilic functional groups that facilitated the water diffusion within the film.

Polymer-Encapsulated ionic liquids as lubricant additives in non-polar oils

While ionic liquids (ILs) have attracted much attention as potential next-generation lubricant additives, their implementation in oil formulations has been hindered by their limited solubility in hydrocarbon fluids and corrosivity. Here, we encapsulate an oil-insoluble IL that has been studied in lubrication science, namely 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([HMIM][TFSI]), within poly(ethylene glycol dimethacrylate-buytl methacrylate copolymer) (poly(EGDM-c-BMA)) microshells using a mini-emulsion polymerization process. The synthesized poly(EGDM-c-BMA)-encapsulated [HMIM][TFSI] microparticles are shown to be dispersible in a non-polar, synthetic oil (i.e., poly-α-olefin). Tribological experiments indicated that the microcapsules act as an additive reservoir that reduces friction by releasing the encapsulated IL at the sliding interface following the mechanical rupture of the polymer shell. X-ray photoelectron spectroscopy (XPS) measurements provided evidence that [HMIM][TFSI] does not tribochemically react on steel surfaces to create a reaction layer, thus suggesting that this IL reduces friction by generating a solid-like, layered structure upon nanoconfinement at sliding asperities, as proposed by previous nanoscale studies. The results of this work do not only provide new insights into the lubrication mechanism of ILs when used as additives in base oils in general, but also establish a new, broadly-applicable framework based on polymer encapsulation for utilizing ILs or other compounds with limited solubility as additives for oil formulations.

Thermal degradation study of poly(ethylene-co-methyl methacrylate) nanospheres synthesized via miniemulsion polymerization

Thermal degradation study of poly(ethylene-co-methyl methacrylate) nanospheres synthesized via miniemulsion polymerization