Cationic Comonomer Research Articles

Preparation of Amino-Functionalized Poly(N-isopropylacrylamide)-Based Microgel Particles.

Responsive cationic microgels are a promising building block in several diagnostic and therapeutic applications, like transfection and RNA or enzyme packaging. Although the direct synthesis of cationic poly(N-isopropylacrylamide) (PNIPAm) microgel particles has a long history, these procedures typically resulted in low yield, low incorporation of the cationic comonomer, increased polydispersity, and pure size control. In this study, we investigated the possibility of the post-polymerization modification of P(NIPAm-co-acrylic acid) microgels to prepare primary amine functionalized microgels. To achieve this goal, we used 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) mediated coupling of a diamine to the carboxyl groups. We found that by controlling the EDC excess in the reaction mixture, the amine functionalization of the carboxyl functionalized microgel could be varied and as much as 6-7 mol% amine content could be incorporated into the microgels. Importantly, the reaction was conducted at room temperature in an aqueous medium and it was found to be time efficient, making it a practical and convenient approach for synthesizing primary amine functionalized PNIPAm microgel particles.

Thermoresponsive Cationic Polymers: PFAS Binding Performance under Variable pH, Temperature and Comonomer Composition.

The versatility and unique qualities of thermoresponsive polymeric systems have led to the application of these materials in a multitude of fields. One such field that can significantly benefit from the use of innovative, smart materials is environmental remediation. Of particular significance, multifunctional poly(N-isopropylacrylamide) (PNIPAAm) systems based on PNIPAAm copolymerized with various cationic comonomers have the opportunity to target and attract negatively charged pollutants such as perfluorooctanoic acid (PFOA). The thermoresponsive cationic PNIPAAm systems developed in this work were functionalized with cationic monomers N-[3-(dimethylamino)propyl]acrylamide (DMAPA) and (3-acrylamidopropyl)trimethylammonium chloride (DMAPAQ). The polymers were examined for swelling capacity behavior and PFOA binding potential when exposed to aqueous environments with varying pH and temperature. Comonomer loading percentages had the most significant effect on polymer swelling behavior and temperature responsiveness as compared to aqueous pH. PFOA removal efficiency was greatly improved with the addition of DMAPA and DMAPAQ monomers. Aqueous pH and buffer selection were important factors when examining binding potential of the polymers, as buffered aqueous environments altered polymer PFOA removal quite drastically. The role of temperature on binding potential was not as expected and had no discernible effect on the ability of DMAPAQ polymers to remove PFOA. Overall, the cationic systems show interesting swelling behavior and significant PFOA removal results that can be explored further for potential environmental remediation applications.

Oxoanion Imprinting Combining Cationic and Urea Binding Groups: A Potent Glyphosate Adsorber.

The use of polymerizable hosts in anion imprinting has led to powerful receptors with high oxyanion affinity and specificity in both aqueous and non-aqueous environments. As demonstrated in previous reports, a carefully tuned combination of orthogonally interacting binding groups, for example, positively charged and neutral hydrogen bonding monomers, allows receptors to be constructed for use in either organic or aqueous environments, in spite of the polymer being prepared in non-competitive solvent systems. We here report on a detailed experimental design of phenylphosphonic and benzoic acid-imprinted polymer libraries prepared using either urea- or thiourea-based host monomers in the presence or absence of cationic comonomers for charge-assisted anion recognition. A comparison of hydrophobic and hydrophilic crosslinking monomers allowed optimum conditions to be identified for oxyanion binding in non-aqueous, fully aqueous, or high-salt media. This showed that recognition improved with the water content for thiourea-based molecularly imprinted polymers (MIPs) based on hydrophobic EGDMA with an opposite behavior shown by the polymers prepared using the more hydrophilic crosslinker PETA. While the affinity of thiourea-based MIPs increased with the water content, the opposite was observed for the oxourea counterparts. Binding to the latter could however be enhanced by raising the pH or by the introduction of cationic amine- or Na+-complexing crown ether-based comonomers. Use of high-salt media as expected suppressed the amine-based charge assistance, whereas it enhanced the effect of the crown ether function. Use of the optimized receptors for removing the ubiquitous pesticide glyphosate from urine finally demonstrated their practical utility.

Importance of pH in Synthesis of pH-Responsive Cationic Nano- and Microgels

While cationic microgels are potentially useful for the transfection or transformation of cells, their synthesis has certain drawbacks regarding size, polydispersity, yield, and incorporation of the cationic comonomers. In this work, a range of poly(N-isopropylacrylamide) (PNIPAM) microgels with different amounts of the primary amine N-(3-aminopropyl)methacrylamide hydrochloride (APMH) as the cationic comonomer were synthesized. Moreover, the pH-value during reaction was varied for the synthesis of microgels with 10 mol% APMH-feed. The microgels were analyzed by means of their size, thermoresponsive swelling behavior, synthesis yield, polydispersity and APMH-incorporation. The copolymerization of APMH leads to a strong decrease in size and yield of the microgels, while less than one third of the nominal APMH monomer feed is incorporated into the microgels. With an increase of the reaction pH up to , the negative effects of APMH copolymerization were significantly reduced. Above this pH, synthesis was not feasible due to aggregation. The results show that the reaction pH has a strong influence on the synthesis of pH-responsive cationic microgels and therefore it can be used to tailor the microgel properties.

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.

Control of Particle Size in the Self-Assembly of Amphiphilic Statistical Copolymers.

A range of amphiphilic statistical copolymers is synthesized where the hydrophilic component is either methacrylic acid (MAA) or 2-(dimethylamino)ethyl methacrylate (DMAEMA) and the hydrophobic component comprises methyl, ethyl, butyl, hexyl, or 2-ethylhexyl methacrylate, which provide a broad range of partition coefficients (log P). Small-angle X-ray scattering studies confirm that these amphiphilic copolymers self-assemble to form well-defined spherical nanoparticles in an aqueous solution, with more hydrophobic copolymers forming larger nanoparticles. Varying the nature of the alkyl substituent also influenced self-assembly with more hydrophobic comonomers producing larger nanoparticles at a given copolymer composition. A model based on particle surface charge density (PSC model) is used to describe the relationship between copolymer composition and nanoparticle size. This model assumes that the hydrophilic monomer is preferentially located at the particle surface and provides a good fit to all of the experimental data. More specifically, a linear relationship is observed between the surface area fraction covered by the hydrophilic comonomer required to achieve stabilization and the log P value for the hydrophobic comonomer. Contrast variation small-angle neutron scattering is used to study the internal structure of these nanoparticles. This technique indicates partial phase separation within the nanoparticles, with about half of the available hydrophilic comonomer repeat units being located at the surface and hydrophobic comonomer-rich cores. This information enables a refined PSC model to be developed, which indicates the same relationship between the surface area fraction of the hydrophilic comonomer and the log P of the hydrophobic comonomer repeat units for the anionic (MAA) and cationic (DMAEMA) comonomer systems. This study demonstrates how nanoparticle size can be readily controlled and predicted using relatively ill-defined statistical copolymers, making such systems a viable attractive alternative to diblock copolymer nanoparticles for a range of industrial applications.

Synthesis and Viscoelastic Properties of Smart Hydrogel

Here we report the synthesis and viscoelastic properties of smart hydrogels based on N-isopropylacrylamide, cationic (3-acrylamidopropyl)trimethylammonium chloride and nanoclay. Hydrogels were prepared by aqueous free radical polymerization. The effect of some salts, N,N '-methylenebisacrylamide, (3-acrylamidopropyl)trimethylammonium chloride and nanoclay content on the viscoelastic properties was studied. Also volume phase transition temperature and thermal behavior of the prepared hydrogels were investigated. Synthetic nanoclay and anionic groups of the bind to the cationic co-monomer units and significantly affected the viscoelasticity and thermal properties of the hydrogels. DSC measurements showed that the volume phase transition temperature of hydrogels depended on nanoclay content. By introducing of co-monomer, 250 mM solution of NaCl 15 mM bis(trifluoromethane)sulfonimide lithium salt (LiNTF2) and laponite nanoclay, a 10, 4, and 3.8 fold increase in elastic module was obtained, respectively, compared to that of the homopolymer PNIPAM hydrogel. With a temperature change from 20 to 45°C for the homopolymer PNIPAM hydrogel in 15 mM LiNTF2, the elastic module grew 5 times larger.

The extent of counterion dissociation at the interface of cationic diblock copolymer nanoparticles in non-polar solvents

HypothesisDiblock copolymer nanoparticles prepared in non-polar solvents that are sterically stabilized but possess ionic functionality from the inclusion of cationic comonomers in the stabilizer shell are known to exhibit complex electrokinetic behavior (Chem. Sci. 9 (2018) 922–934). For example, core-shell nanoparticles with cationic comonomers located solely within the shell layer have lower magnitude electrophoretic mobilities than nanoparticles containing the same cationic comonomers located within the core, whereas nanoparticles prepared using a minor fraction of steric stabilizer chains containing cationic comonomer repeat units have comparable electrophoretic mobilities to nanoparticles prepared with this cationic comonomer solely located within the core. We hypothesize that these observations can be explained in terms of the strength of the Coulombic interaction between counterions and the nanoparticle interface. ExperimentsThe highly-fluorinated anionic counterion associated with these cationic nanoparticles is studied by 19F nuclear magnetic resonance (NMR) spectroscopy in n-dodecane. This revealed only one type of 19F environment for a soluble macromolecular cation (the oil-soluble steric stabilizer chains used to prepare the nanoparticles), whereas two distinct environments were observed for the sterically-stabilized cationic nanoparticles. Both 19F diffusion NMR and 19F–13C heteronuclear single quantum correlation (HSQC) measurements support the existence of two environments for this counterion. FindingsThe existence of two distinct 19F environments for the highly-fluorinated anion associated with the sterically-stabilized nanoparticles demonstrates the presence of spectroscopically distinguishable populations of ion pairs and of fully dissociated free anions. 19F NMR spectra recorded for sterically-stabilized nanoparticles with a fully ionic shell (all stabilizer chains containing the cationic comonomer) and those with a partly ionic shell (10% of stabilizer chains containing the cationic comonomer) reveal a higher proportion of dissociated anions in the partly ionic case. This suggests a stronger Coulombic interaction between counterions and the cationic interface when the shell is fully ionic, which accounts for the observed reduction in the magnitude of the electrophoretic mobility.

Preparation, stability and film properties of cationic polyacrylate latex particles with various substituents on the nitrogen atom

Cationic latexes have received wide attention due to their special properties and potential applications in wood coatings, fabric treatment, etc. However, the practical application of cationic latexes was hindered due to their poor stability, especially the alkali resistance stability. In this work, various stable cationic polyacrylate latexes were prepared by an efficient route. Three cationic comonomers, i.e., methacrylatoethyl trimethyl ammonium chloride (DMC), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and 2-aminoethyl methacrylate hydrochloride (AEMH), were used in the aqueous semi-continuous seeded emulsion polymerization of methyl methacrylate (MMA) and butyl acrylate (BA) using cetyl trimethyl ammonium bromide (CTAB) and 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIBI) as the cationic emulsifier and initiator, respectively. The alkali resistance of the latex could be significantly improved by the addition of cationic monomer DMC and be simply tuned by adjusting DMC dosage. The improved stability of the latex might originate from the higher charge density on the surface of the latex by the introduction of DMC. Moreover, the effects of initiator dosage, emulsifier dosage and different cationic comonomers on the latex preparation and the film properties were also systematically investigated. This work not only introduces an efficient route to prepare cationic latexes with superior stability, but also paves the way for latexes to be used in applications such as textile finishing, paper industry, and biomedical field, etc.

Development of Smart Polymer Microparticles through Suspension Polymerization for Treatment of Schistosomiasis

AbstractSchistosomiasis is a parasitic disease that affects millions of people, especially low‐income people, and is considered a major public health problem in underdeveloped countries. The drug used most often for the treatment of the disease is praziquantel (PZQ), which has a strong and characteristic bitter taste that makes treatment of children inconvenient. For this reason, the present work investigates the development of smart pH‐sensitive polymer microparticles produced through suspension polymerizations to be used as vehicles for the controlled release of praziquantel in the body. The microparticles are produced through copolymerization of methyl methacrylate and the cationic comonomers diethylaminoethyl methacrylate or dimethylaminoethyl methacrylate. The obtained results indicate that microparticles with sizes in the range of 10–1100 µm can be formed successfully, allowing high PZQ encapsulation efficiencies (>80%). Zeta potential analyses and drug release assays confirm the pH‐sensitive responses of the cationic copolymers, leading to effective release of PZQ (around 80% in pH 1.2) in acidic media that simulate the organic fluids present in the stomach.

Synthesis of Polymeric Nanoparticles by Emulsion Polymerization for Particle Self-Assembly Applications.

Polymeric nanoparticles with sufficient solid concentration could be synthesized by emulsion polymerization without using surfactants. The polymeric nano-colloids with surface functional groups were synthesized to obtain carboxylated polystyrene beads or amidine polystyrene nanoparticles. Sodium styrene sulfonate was also adopted for the synthesis of sulfonated polystyrene nanoparticles less than 50 nm in diameter using KPS as an initiator. The diameter of the carboxylated particles could be controlled by adjusting the reaction parameters such as the amount of monomer, cross-linker, and polymerization temperature. The range of the diameter of the resulting polymeric beads was 100 to 200 nm, which is useful size range for bio-sensing purposes. Amidine polystyrene nanoparticles less than 50 nm could be fabricated using a cationic comonomer, MTC. As an application of the polymeric beads, the porous inorganic particles could be synthesized by colloidal templating using emulsions as micro-reactors.

Surfactant-free emulsion copolymerization of styrene and a cationic comonomer with two positively charged groups

Near-monodisperse, stabilized latex particles were prepared by surfactant-free emulsion copolymerization of styrene with a water-soluble cationic comonomer StMV having two positively charged groups. Unlike previously reported surfactant-free emulsion copolymerization systems, very small polymer nanoparticles (≤ 70 nm as indicated by transmission electron microscopy studies) were produced even though the StMV/St molar ratio was no more than 1/100. The effects of initiator concentration, StMV concentration, and styrene concentration on the size of the latex particles were investigated. The polymerization kinetics was monitored by transmission electron microscopy, monomer conversion, dynamic light scattering, and visual inspection. This study is expected to enrich the surfactant-free syntheses of cationic polystyrene latex and can provide useful information to construct cucurbit[n]uril-based supramolecular polymer colloids.

Preparation and flocculation properties of biodegradable konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride)

Preparation of konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride) (KGM-g-PTMAAC) was carried out using KGM as polysaccharide matrix and TMAAC as cationic comonomer to develop biodegradable flocculants. The structure of KGM-g-PTMAAC was characterized by FTIR, 13C solid-state NMR, elemental analysis (EA) and SEM. Thermal properties of KGM-g-PTMAAC were studied by thermal gravimetric (TG) analysis. In addition, flocculation properties of KGM-g-PTMAAC were investigated in a kaolin suspension. The results of the FTIR, NMR, and EA showed that the cationic moiety containing quaternary ammonium has been introduced in the backbone of KGM. SEM images indicated that the surface of KGM-g-PTMAAC was rougher than that of KGM. TG results indicated that the thermal stability of KGM-g-PTMAAC was different to that of KGM. The obtained products had a good biodegradable performance. Moreover, the results of the flocculation test showed that KGM-g-PTMAAC could be potentially used as a good flocculating agent.

In Situ Incorporation of Praziquantel in Polymer Microparticles through Suspension Polymerization for Treatment of Schistosomiasis

AbstractSchistosomiasis is one of the major public health problems worldwide. Even though this is a common illness among preschool children in poor countries, treatment is carried out mainly through the administration of praziquantel tablets, which has some disadvantages, such as the strong bitter taste. As an alternative to overcome this problem, the development of new encapsulated praziquantel formulations is demanded. For this reason, suspension polymerizations are carried out for the in situ encapsulation of praziquantel into polymer microparticles, using methyl methacrylate (MMA) and cationic compounds (diethylaminoethyl methacrylate, DEAEMA, and dimethylaminoethyl methacrylate, DMAEMA) as comonomers. This technique allows for the preparation of polymer microparticles with high encapsulation efficiencies (>90%) with characteristic sizes ranging from 0.5 to 1500 µm. Drug release profiles show that praziquantel is released from poly(methyl methacrylate) microparticles slowly due to the existence of strong diffusional resistance. On the other hand, the addition of cationic comonomers renders polymer particles sensitive to pH variations, allowing for faster release of praziquantel in acidic environments, as found in the stomach.

Synthesis and Characterization of Ampholytic Flocculant CPCTS-g-P (CTA-DMDAAC) and Its Flocculation Properties for Microcystis Aeruginosa Removal

The ampholytic chitosan based flocculant carboxylated chitosan graft-(3-chloro-2-hydroxypropyl) trimethylammonium chloride-dimethyl diallyl ammonium chloride (CPCTS-g-P (CTA-DMDAAC)) was synthesized by photo polymerization using carboxylated chitosan (CPCTS), 3-chloro-2-chloropropyltrimethylammonium chloride (CTA) and dimethyldiallylammonium chloride (DMDAAC) as the cationic co-monomers. The effects of monomer concentration, the ratio of CPCTS and cationic monomers, cationic degree, initiator time, photoinitiator concentration, and pH value on the properties of CPCTS-g-P (CTA-DMDAAC) were studied. The microcystis aeruginosa that was cultured in laboratory was used for CPCTS-g-P (CTA-DMDAAC) flocculation tests. The effects of CPCTS-g-P (CTA-DMDAAC) dosage, pH value and G value on flocculation performance were investigated. The maximum removal rate of chlorophyll-a (Chl-a) and chemical oxygen demand (COD) that were obtained by CPCTS-g-P (CTA-DMDAAC) were 98.8% and 96.5% under the conditions of dosage 4 mg/L, pH 7 and G value 200 s−1, respectively. The flocculation experiments showed that chitosan-based flocculant CPCTS-g-P (CTA-DMDAAC) had better flocculation performance than commercially available flocculants cationic polyacrylamide (CPAM), Polyferric Sulfate (PFS), and polymeric aluminium (PAC).

Sequence Control as a Powerful Tool for Improving the Selectivity of Antimicrobial Polymers.

Antimicrobial polymers appear as a promising alternative to tackle the current development of bacterial resistance against conventional antibiotics as they rely on bacterial membrane disruption. This study investigates the effect of segmentation of hydrophobic and cationic functionalities on antimicrobial polymers over their selectivity between bacteria and mammalian cells. Using RAFT technology, statistical, diblock, and highly segmented multiblock copolymers were synthesized in a controlled manner. Polymers were analyzed by HPLC, and the segmentation was found to have a significant influence on their overall hydrophobicity. In addition, the amount of incorporated cationic comonomer was varied to yield a small library of bioactive macromolecules. The antimicrobial properties of these compounds were probed against pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis), and their biocompatibility was tested using hemolysis and erythrocyte aggregation assays, as well as mammalian cell viability assays. In all cases, diblock and multiblock copolymers were found to outperform statistical copolymers, and for polymers with a low content of cationic comonomer, the multiblock showed a tremendously increased selectivity for P. aeruginosa and S. epidermidis compared to its statistical and diblock analogue. This work highlights the remarkable effect of segmentation on both the physical properties of the materials as well as their interaction with biological systems. Due to the outstanding selectivity of multiblock copolymers toward certain bacteria strains, the presented materials are a promising platform for the treatment of infections and a valuable tool to combat antimicrobial resistance.

Study on morphology, molecular weight and thermal properties of composite microspheres prepared by controlling feeding ways and reaction time

ABSTRACTThe application of composite microspheres closely lies on their morphology and properties. In this work, carbon nanotubes (CNTs) reinforced composite microspheres were prepared via in situ polymerization: methyl methacrylate was selected as matrix to copolymerize with cationic comonomer 2‐(methacryloyloxy)ethyltrimethyl ammonium chloride, using CNTs as nanofillers to fabricate composite microspheres. The morphology, molecular weight, and thermal properties of obtained composite microspheres with different monomer feeding ways (batch polymerization and dropwise monomer feeding procedure) and reaction time (1–6 h) were investigated. The results revealed that dropwise monomer feeding procedure leaded to remarkably decreased diameter of composite microspheres. Compared with polymer microspheres, the addition of CNTs resulted in earlier formation of composite microspheres. When the reaction time was controlled for 1–6 h, the morphology of the composite microspheres underwent a shape change from deformed particles to spherical structure. Although reaction time had no significant effect on molecular weight, the thermal property was gradually improved with increase of reaction time. For ensuring the effectiveness of the produced composite microspheres and tailoring them for any specific application, our investigation shows significant reference value on choosing feeding ways and controlling reaction time to obtain different morphology microspheres. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45741.

Tailoring the physico-chemical properties and elasticity of poly(hydroxy-functional methacrylate)-based cationically charged gel beads: Combined hydrophobicity and mechanical durability through frozen droplets

This study describes the experimental methodology to obtain hydroxy-functional methacrylate-based gel beads in millimeter-sized under production conditions by addition of the frozen pre-gel solution into the silicon oil as continuous phase using tetraethyleneglycol dimethacrylate (TEGDMA) as the crosslinking agent. Weakly basic cationic comonomer N,N-dimethylaminoethyl methacrylate (DMAEMA) was included into the polymerization procedure for the production of uniform polycationic moities exhibiting a drastic response against pH. The aim of this work is to determine the actual conditions for optimum bead production and to provide poly(hydroxypropyl methacrylate-co-N,N-dimethylaminoethyl methacrylate)-based P(HPMA-co-DMAEMA) gel beads with simple tools for the physical characterization. By the proposed experimental method, the physico-chemical properties of P(HPMA-co-DMAEMA) gel beads can be controlled by adjusting the pH, temperature of solution, ionic strength as well as the structure of the gel network. From the uniaxial compression tests, the swelling dependent stress–strain characteristics of resulting gel beads was evaluated. The obtained results were consistent with Hertzian elasticity, and were analyzed in terms of the compression modulus of the bead samples. It was found that force acting on the gel beads is the power-law function of the deformation F≈ΔD1.48 which is very close to the theoretical exponent 1.5 predicted by the Hertz equation. The water absorption capacities of P(HPMA-co-DMAEMA) gel beads with basic functional groups were repeatedly measured to obtain the optimal preparation conditions according to the variations of the bead diameters. Its maximal water absorption capacity appeared as 48 times among from 2.3mm to 11.0mm of swollen bead diameters. The swelling equilibria in various aqueous solutions were used to estimate the physico-chemical parameters asa function of gel bead size and swelling equilibrium capacity by correlating with the Flory-Rehner theory.

Dewatering Oil Sands Mature Fine Tailings (MFTs) with Poly(acrylamide-co-diallyldimethylammonium chloride): Effect of Average Molecular Weight and Copolymer Composition

Copolymers of acrylamide and cationic comonomers such as diallyldimethylammonium chloride can effectively dewater solid suspensions containing negatively charged fine particles. A good example of such suspensions is oil sands mature fine tailings (MFTs). However, little is known about the impact of the microstructure of copolymers in dewatering performance. In this study, we used a surface response methodology to systematically assess the impact of chemical composition and average molecular weight of poly(acrylamide-co-diallyldimethylammonium chloride) in dewatering MFTs. We controlled the chemical composition and average molecular weight of the copolymers by manipulating feed monomer/comonomer ratios and initiator concentration. We found both the copolymer composition and the molecular weight averages were statistically significant variables for initial settling rates and supernatant turbidities of flocculated MFTs. However, capillary suction time and resistance to filtration depended only on copolymer c...

In situ charge neutralization-controlled particle coagulation and its effects on the particle size distribution in the one-step emulsion polymerization

A novel approach to prepare sub-200nm, narrowly dispersed polystyrene latex particles is proposed for the emulsion polymerization of a ca. 40wt% solid-content solution. The presented method exploits the cationic comonomer methacryloxyethyltrimethyl ammonium chloride (MATMAC) or the initiator 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (AIBA) to generate cationic oligomeric radicals shielded the negatively charged surfactant molecules adsorbed on the particles surface, further induced particle coagulation by in situ charge neutralization. By adjusting the types and amounts of the comonomer, the extent of the in situ charge neutralization is controlled. In consequence, the extent of the particle coagulation is controlled, resulting in the production of large-size latex particles. The particle coagulation induced by in situ charge neutralization occurs at the particle nucleation stage, which extends the times of particle completive growth and reversible coagulation, and therefore, narrowed the width of the particle size distribution of the ultimate latex particles. The resulting colloidal latexes containing 40wt% solid content are very stable by presenting the absolute value of zeta potentials larger than 40mV. This approach is likely to be used for large-scale industrial productions of narrowly dispersed polymer particles.