Methacrylamido Propyl Trimethylammonium Chloride Research Articles

Preparation of a Lignin-Based Cationic Flocculant and Its Application in Kaolin Suspension Treatment.

The preparation of an environmentally friendly and efficient flocculant for solid-liquid separation in industrial wastewater is highly important. In this study, a novel cationic flocculant (AL-g-PAMA) was synthesized by a thermal initiation method using alkali lignin (AL) as the main chain and acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) as the grafted side chains. The structure, thermal stability, and surface morphology of the copolymers were investigated by various characterization methods. The results indicated the successful synthesis of AL-g-PAMA. AL-g-PAMA was applied to improve solid-liquid separation in kaolin suspensions. The results showed that AL-g-PAMA had excellent flocculation-sedimentation and dewatering efficiency. When the dosage of AL-g-PAMA #5 was 600.0 g/t(s), the thickness of the compressed layer was 2.2 cm, the floc settling velocity was 24.1 cm/min, and the transmittance of the supernatant was 84.0%. The moisture content of the filter cake decreased from 55.0% to 43.4% after treatment with AL-g-PAMA #5. The results of zeta potential and focused beam reflectance measurement (FBRM) analysis indicated that bridging and electroneutralization were the main flocculation mechanisms. Therefore, this study extends the potential for using lignin as a bioflocculant and provides a feasible approach to efficiently purify high-turbidity wastewater.

Synthesis of branched cationic flocculant and its performance in treating industrial wastewater with different compositions

This paper proposes a polymer reaction method to introduce a branched structure into cationic polymers' side chains to improve the flocculation performance of the cationic polymer. By using reaction between epoxide compound (EP) and secondary amine in the copolymer (PDD) of methacrylamido propyl trimethyl ammonium chloride (DMC) and diallylamine (DAA), a branched structure was introduced into the side chain of PDD. Three kinds of typical industrial wastewater including sodium humate (NaHA) solution, bentonite suspension, and oilfield produced water (PW) were chosen to be treated by the branched PDD. The pollutants in the three wastewaters had different forms and they were water-soluble organics, solid particles, and liquid droplets, respectively. The effects of flocculant structure and flocculation process on flocculation performance were discussed. The experimental results showed that branched PDD can effectively improve the flocculation performance of PDD. DRE contains an aromatic ring, which may enhance the interaction between PDD-g-DRE and NaHA to promote flocculation. The PDD-g-GTE obtained from the reaction of GTE and PDD contains many hydroxyl groups, which can form hydrogen bonds with the silicon hydroxyl groups on the surface of bentonite to promote flocculation. TDM contains two benzene rings, which made PDD-g-TDM have hydrophobicity. The flocculation can be enhanced because of the hydrophobic interaction between PDD-g-TDM and oil droplets. This work provides a new understanding of the synthesis and performance of branched cationic polymer flocculants.

Studies on Antifungal Properties of Methacrylamido Propyl Trimethyl Ammonium Chloride Polycations and Their Toxicity In Vitro.

The biological activity of polycations is usually associated with their biocidal properties. Their antibacterial features are well known, but in this work, observations on the antifungal properties of macromolecules obtained by methacrylamido propyl trimethyl ammonium chloride (MAPTAC) polymerization are presented. The results, not previously reported, make it possible to correlate antifungal properties directly with the structure of the macromolecule, in particular the molecular mass. The polymers described here have antifungal activity against some filamentous fungi. The strongest effect occurs for polymers with a mass of about 0.5 mDa which have confirmed activity against the multidrug-resistant species Scopulariopsis brevicaulis, Fusarium oxysporum, and Fusarium solani, as well as the dermatophytes Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton interdigitale, and Trichophyton tonsurans. In addition, this publication describes the effects of these macromolecular systems on serum and blood components and provides a preliminary assessment of toxicity on cell lines of skin-forming cells, i.e., fibroblasts and keratinocytes. Additionally, using a Franz diffusion chamber, a negligibly low transport of the active polymer through the skin was demonstrated, which is a desirable effect for externally applied antifungal drugs. IMPORTANCE Infectious diseases are a very big medical, social, and economic problem. Even before the COVID-19 pandemic, certain infections were among of the most common causes of death. The difficulties in the treatment of infectious diseases concern in particular fungal diseases, against which we have only a few classes of drugs represented by a few substances. The publication presents the preliminary results of the in vitro antifungal activity studies of four MAPTAC polymers on different fungal species and their cytotoxicity to human cells (fibroblasts and keratinocytes). The paper also compares these properties with analogous ones of two commonly used antifungal drugs, ciclopirox and terbinafine.

Aqueous phase synthesis of ion-imprinted cryogel for paper-based colorimetric detection of As(V) with high selectivity.

A novel hydrophilic As(V) ion-imprinted cryogel (IIC) was green prepared by cryogelation in aqueous environment which was coincident with the adsorption condition and can improve the specific recognition performance. The methacrylamido propyl trimethyl ammonium chloride (MPTAC) was selected as the functional monomer and the saturated adsorption capacity of the prepared IIC and NIC were 55.0mg/g and 29.4mg/g, and with high imprinting factor of 1.87. Additionally, the prepared IIC showed admirable reusability and highselectivity, and the recovery was in the range 81.2-97.9% with RSD range of 1.9-4.3%, which was similar to the value obtained by hydride generationatomic absorption spectrometry. IIC can be used as solid material for colorimetric detection at the ultraviolet wavelength of 858nm without color interference of material matrix, in the range 5-200μg/L (R2 = 0.990)with a detection limit of 0.970 µg/L. Obviously, this synthetic strategy provides a simple, efficient, and green method for the preparation of water-compatible ion-imprinted polymers providingselectiveseparation and detection of trace As(V) in real complex samples.

Phase‐Transition‐Triggered Optical Switching for Multistage Information Encryption/Decryption

AbstractIt remains challenging to enable the optical switching for safety‐improved information encryption/decryption on a gel platform. Herein, a water swelling‐induced optical‐switching strategy is reported that can achieve multistage information encryption/decryption on an organohydrogel surface. Cationic moieties of methacrylamido propyl trimethyl ammonium chloride (MPTAC) and hydrophobic fluorophores of (2‐(4‐vinylphenyl) ethene‐1,1,2‐triyl) tribenzene (TPE) are copolymerized into hydrophilic polyacrylamide network. The cationic moieties are capable of increasing the water swelling ability of the network, and the fluorophores endow the network with weak blue fluorescence. Upon low swelling with water (swelling ratio in weight < 50), hydrophobic fluorophores of TPE aggregate to enhance the fluorescence under ultraviolet light. This process is accompanied with the phase transition of organohydrogel into a non‐transparent state. After being saturated with water, the fluorescence disappears and the organohydrogel returns to the transparent state. Such water swelling‐induced optical switching can be used for multistage information encryption/decryption with improved safety. Various information patterns are created on the surface of organohydrogel by laser cutting to demonstrate the complex information encryption/decryption processes. This strategy not only provides a meaningful inspiration for information encryption/decryption but also enables an optical‐switching platform for potential anti‐counterfeiting and displaying.

A strong anion exchanger of poly(glycidyl methacrylate-divinylbenzene) substrate functionalized with cationic quaternary ammonium monomer.

A strong anion exchanger applied for ion chromatography is described by grafting methacrylamido propyl trimethyl ammonium chloride onto hydrolyzed poly(glycidyl methacrylate-divinylbenzene) substrate. The anion exchanger has been in detail characterized and the final capacity of the anion exchanger can be readily manipulated by different monomer amounts. It exhibited obvious temperature-sensitive properties and large tolerance to the samples with high ionic strength. The obtained anion exchanger demonstrated effective separation ability towards the common seven inorganic anions within 12 min and high separation efficiency, for example, 58 000/m of theoretical plate count for chloride.

A strategy for effective recovery of salvianolic acid a from Salvia miltiorrhiza (Danshen) through multiple interactions

Salvianolic acid A (SAA) has high pharmacological activity and is widely used in the treatment of various diseases. We reported herein a strategy for effective adsorption of SAA from aqueous solution by surface molecularly imprinted magnetic nanoparticle (SIMNP). 4-(acryloyloxy)phenylboronic acid, 1-vinylimidazole and methacrylamido propyl trimethyl ammonium chloride were chosen as functional monomers . 1-vinylimidazole not only neutralizes the acidity of SAA solution to help phenylboronic acid react with ortho-phenolic hydroxyl groups of SAA quickly and stably, but also captures SAA through electrostatic interaction and hydrogen bond. Besides, the introduction of positively charged methacrylamido propyl trimethyl ammonium chloride can accelerate the adsorption kinetics . Adsorption kinetically follows a pseudo-second-order model and achieves equilibrium within 10 min at 298.15 K with high selectivity. And the maximum adsorption capacity can be determined to be 1117.6 mg/g by Langmuir adsorption model. Adsorption mechanism involves the formation of covalent bond , electrostatic interaction and hydrogen bond. This work indicates that SIMNP is a promising adsorbent to realize effective capture of SAA from aqueous solution.

Physicochemical characterization and flocculation performance evaluation ofPAC/PMAPTACcomposite flocculant

AbstractA novel inorganic–organic composite flocculant was prepared with polyaluminum chloride (PAC) and poly(methacrylamido propyl trimethyl ammonium chloride) (PMAPTAC). To understand the physicochemical characterization of PAC/PMAPTAC and evaluate its flocculation efficiency, the interactions of PAC and cationic polymer were investigated, then the characterization and flocculation performance of PAC/PMAPTAC and PAC/Poly‐dimethyldiallylammonium chloride (PDMDAAC) were compared. The results showed that there were obvious interactions between PAC and cationic polymer in composite flocculant. The cationic polymer chain exhibited a coiled state in PAC solution, and the curly degree of PMAPTAC chain was lower than that of PDMDAAC due to the intermolecular association of methyl of PMAPTAC. The cationic polymer enhanced the charge neutralization ability of PAC and changed the aluminum hydrolysis polymerization species of PAC from low and medium polymeric species to high‐polymeric species. The flocculation sedimentation experiments turned out that the charge neutralization and bridging ability of PAC/PMAPTAC was higher than that of PAC/PDMDAAC, and the increase of molecular weight or content of PMAPTAC in PAC/PMAPTAC could enhance the charge neutralization and adsorption bridging ability simultaneously. The enhanced effects may come from the exist of polymer and the interactions between PAC and cationic polymer in composite flocculant.

Synthesis and evaluation of cationic flocculant P(DAC-PAPTAC-AM) for flocculation of coal chemical wastewater

In this study, a high-efficiency cationic flocculant, P(DAC-MAPTAC-AM), was successfully prepared using UV-induced polymerization technology. The monomer Acrylamide (AM): Acryloxyethyl Trimethyl ammonium chloride (DAC): methacrylamido propyl trimethyl ammonium chloride (MAPTAC) ratio, monomer concentration, photoinitiator concentration, urea content, and cationic monomer DAC:MAPTAC ratio, light time, and power of high-pressure mercury lamp were studied. The characteristic groups, characteristic diffraction peaks, and characteristic proton peaks of P(DAC-MAPTAC-AM) were confirmed by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), 1H nuclear magnetic resonance spectrometer (1H NMR), and scanning electron microscopy (SEM). The effects of dosage, pH value, and velocity gradient (G) value on the removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol by poly aluminum ferric chloride (PAFC), P(DAC-MAPTAC-AM), and PAFC/P(DAC-MAPTAC-AM) in the flocculation treatment of coal chemical wastewater were investigated. Results showed that the optimal conditions for the flocculation of coal chemical wastewater using P(DAC-MAPTAC-AM) alone are as follows: dosage of 8–12 mg/L, G value of 100–250 s − 1, and pH value of 4–8. The optimal dosage of PAFC is 90–150 mg/L with a pH of 2–12. The optimal dosage for PAFC/P(DAC-MAPTAC-AM) is as follows: PAFC dosage of 90–150 mg/L, P(DAC-MAPTAC-AM) dosage of 8–12 mg/L, and pH range of 2–6. When P(DAC-MAPTAC-AM) was used alone, the optimal removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol were 81.0%, 35.0%, 75.0%, and 80.3%, respectively. PAFC has good tolerance to wastewater pH and good pH buffering. Thus, the flocculation treatment of coal chemical wastewater using the PAFC/P(DAC-MAPTAC-AM) compound also exhibits excellent resistance and buffering capacity.

Synthesis of Hydrophobic Cationic Polymeric Flocculants by the Introduction of a Hydrophobic Monomer, Cationic Monomer and the Application in Sludge Dewatering

Dewatering pre-treatment, chemical conditions for sludge are practical approaches to advance the performance of sludge-dewatering, hence lessen the cost of sludge transportation and treatment. Cationic polymeric flocculants are used as chemical regulators because of their excellent performance and economic advantages. Current research focused on synthesizing flocculants Polyacrylamide, methacrylamido propyl trimethyl ammonium chloride, Lauryl acrylate, and Poly Acrylamide, methacrylamido propyl trimethyl ammonium chloride (PAT). The synthesis was achieved by ultraviolet initiated (UV-initiated)-induced polymerization technique. The chemical composition of the samples was investigated using Fourier transform infrared (FTIR) spectroscopy and hydrogen nuclear magnetic resonance (1H NMR). This study also evaluated the thermal stability of PATL and PAT by using thermogravimetric/differential scanning calorimetry (TGA). Moreover, the results of scanning electron microscopy (SEM) confirmed the strong floc structure has the ability to form porous and channel construction, making the filter cake a constructive drainage way. It is able to be used for water release and therefore helps to improve dehydration capacity. The hydrophobic flocculants properties in water were investigated by initiator concentration, initiation time and urea concentration. The experimental results confirmed that the optimal values for preparation of PATL were composed of initiator concentration of 0.4 wt.‰, urea level of 1.2 wt.‰; molar ratio of MPTAC to AM (5:95), irradiation time of 60 min and flocculants intrinsic viscosity of 1350 mL/g. Furthermore, it was found that PATL had stronger hydrophobic collaboration with satisfactory water solubility and also improved the dewatering performance. Sludge dewatering experiments confirmed that filter cake moisture content (FCMC) and specific resistance to filtration (SRF) for PATL flocculants reached to 65% and 6 × 1012 m/kg, respectively at the optimal dosage of dry solids about 30 mg · L–1 of sludge, exhibiting better performance than the conventional cationic flocculants (PAT).

Synthesis of Diblock Polyampholyte PAMPS-b-PMAPTAC and Its Adsorption on Bentonite.

To study the adsorption of polyampholyte on bentonite (Bent), a block polyampholyte, PAMPS-b-PMAPTAC, comprised of 2-Acrylamido-2-Methylpropane Sulfonic Acid (AMPS) units and Methacrylamido Propyl Trimethyl Ammonium Chloride (MAPTAC) units, was synthesized using reversible addition-fragmentation chain transfer polymerization (RAFT) method. The block polyampholyte samples were characterized by FTIR, 1H NMR and Gel Permeation Chromatography (GPC). The microstructure of block polyampholyte and random polyampholyte in deionized water indicated that uneven distribution of charged groups increased the entanglement of polymer chains. Addition of salt weakened the electrostatic interactions among charged groups, and, therefore, increased the zeta potential of polyampholyte in aqueous solutions. The adsorptive behaviors of PAMPS-b-PMAPTAC on Bent were studied using elemental analysis, and the effects of external factors were considered. The adsorption equilibrium of polymers on Bent was reached after 12 h. Increased temperature and increased salinity exerted a positive and negative effect on the adsorption of polyampholyte, respectively. The molecular weight played as the decisive factor for the adsorption of polyampholyte in the absence of NaCl, while the content of cationic groups acted as the main factor in the presence of NaCl. Block polyampholyte exhibited higher adsorption than random polyampholyte in the absence of salt. XRD results also indicated that block polyampholyte had a better intercalation effect than random polyampholyte.

Water-Deactivated Polyelectrolyte Hydrogel Electrolytes for Flexible High-Voltage Supercapacitors.

With the boom of flexible electronic products and wearable devices, flexible energy storage devices, for example, supercapacitors with high performance, are attracting increasing interest. A flexible water-deactivated polyelectrolyte hydrogel electrolyte with good mechanical properties and high ionic conductivity was prepared by using an anionic polymer, carboxy methyl cellulose, and a cationic monomer, methacrylamidopropyltrimethyl ammonium chloride. It was then applied in a supercapacitor with flexible activated carbon electrodes. This flexible supercapacitor possesses a high operating voltage of 2.1 V owing to the low electrochemical activity for water within the hydrogel as a result of the 'molecular cages' effect and hydrophilic interactions between functional groups and surrounding water molecules. Furthermore, this supercapacitor exhibits good flexibility and tailorability. As the first example of water-deactivated polyelectrolyte hydrogel electrolytes in applications involving flexible high-voltage supercapacitors, this work provides a platform for the design of energy storage devices with high energy density for flexible and wearable electronic devices.

Photo-grafting polymerization, microstructure and hydrophilicity of spun-blown polypropylene nonwoven fabrics

The non-polarity and poor hygroscopicity of polypropylene (PP) impede its wide application. The polar monomers, glycidyl methacrylate (GMA), hydroxyethyl methacrylate (HEMA) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) were grafted onto the spun-blown polypropylene nonwoven fabric (SMS) under ultraviolet irradiation, and the subsequent functionalization of the grafted fabrics was implemented as well. The results show that both the monomer and the polymer of HEMA are hydrophilic and are grafted uniformly onto the fabric surface as well as into the melt-blown layer with the hydrophilicity being enhanced slightly, whereas the hydrophilic monomer yet the hydrophobic polymer of MAPTAC prefer to be grafted onto the melt-blown fibre with the wicking effect. Both the monomer and the polymer of GMA are hydrophobic and are favourably grafted into the meltblown layer with no hydrophilicity being improved. The grafting diminishes the fibre crystallinity and melting temperature, especially significant for the graftings of hydrophobic polymers, PGMA and PMAPTAC. All the grafting reduces the water flux of the grafted fabrics no matter what the grafting polymers are hydrophilicity or hydrophobicity not.

UV-initiated polymerization of acid- and alkali-resistant cationic flocculant P(AM-MAPTAC): Synthesis, characterization, and application in sludge dewatering

Abstract Cationic polyacrylamide (CPAM) has been the focus of research in environmental engineering field, particularly in sludge dewatering. However, poor stability of the existing cationic polyacrylamide has limited its application. In the face of the current complex sewage/sludge environment, CPAM with high efficiency, good stability and economy is remarkably desired in this field. In this study, a CPAM (PAMA) with high acid and alkali resistance was synthesized through copolymerization of acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) under ultraviolet (UV) radiation. The structure, morphology as well as the thermal decomposition property were analyzed through instrumental analysis. Furthermore, influencing factors of the copolymerization reaction were investigated and discussed in detail. The dewatering performance of PAMA was also evaluated by measuring the supernatant residual turbidity (RT), moisture content of the filter cake (FCMC), and specific resistance to filtration of the sludge (SRF). The RT, FCMC, and SRF reached 4.70 NTU, 71%, and 3.94 (1012 m Kg−1), respectively, at 40 mg L−1 of PAMA-25-15.1 and pH of 6.0. Furthermore, these indices did not increase with the pH changes of the original sludge, and which indicated a high acid and alkali resistance of PAMA.

Polyion Complex Vesicles with Solvated Phosphobetaine Shells Formed from Oppositely Charged Diblock Copolymers.

Diblock copolymers consisting of a hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) block and either a cationic or anionic block were prepared from (3-(methacrylamido)propyl)trimethylammonium chloride (MAPTAC) or sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS). Polymers were synthesized via reversible addition-fragmentation chain transfer (RAFT) radical polymerization using a PMPC macro-chain transfer agent. The degree of polymerization for PMPC, cationic PMAPTAC, and anionic PAMPS blocks was 20, 190, and 196, respectively. Combining two solutions of oppositely charged diblock copolymers, PMPC-b-PMAPTAC and PMPC-b-PAMPS, led to the spontaneous formation of polyion complex vesicles (PICsomes). The PICsomes were characterized using 1H NMR, static abd dynamic light scattering, transmittance electron microscopy (TEM), and atomic force microscopy. Maximum hydrodynamic radius (Rh) for the PICsome was observed at a neutral charge balance of the cationic and anionic diblock copolymers. The Rh value and aggregation number (Nagg) of PICsomes in 0.1 M NaCl was 78.0 nm and 7770, respectively. A spherical hollow vesicle structure was observed in TEM images. The hydrodynamic size of the PICsomes increased with concentration of the diblock copolymer solutions before mixing. Thus, the size of the PICsomes can be controlled by selecting an appropriate preparation method.

UV-initiated template copolymerization of AM and MAPTAC: Microblock structure, copolymerization mechanism, and flocculation performance

Flocculation as the core technology of sludge pretreatment can improve the dewatering performance of sludge that enables to reduce the cost of sludge transportation and the subsequent disposal costs. Therefore, synthesis of high-efficiency and economic flocculant is remarkably desired in this field. This study presents a cationic polyacrylamide (CPAM) flocculant with microblock structure synthesized through ultraviolet (UV)-initiated template copolymerization by using acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) as monomers, sodium polyacrylate (PAAS) as template, and 2,2'-azobis [2-(2-imidazolin-2-yl) propane] dihydrochloride (VA-044) as photoinitiator. The microblock structure of the CPAM was observed through nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) analyses. Furthermore, thermogravimetric/differential scanning calorimetry (TG/DSC) analysis was used to evaluate its thermal decomposition property. The copolymerization mechanism was investigated through the determination of the binding constant MK and study on polymerization kinetics. Results showed that the copolymerization was conducted in accordance with the I (ZIP) template polymerization mechanism, and revealed the coexistence of bimolecular termination free-radical reaction and mono-radical termination in the polymerization process. Results of sludge dewatering tests indicated the superior flocculation performance of microblock flocculant than random distributed CPAM. The residual turbidity, filter cake moisture content, and specific resistance to filtration reached 9.37 NTU, 68.01%, and 6.24 (1012 m kg−1), respectively, at 40 mg L−1 of template poly(AM-MAPTAC) and pH 6.0. Furthermore, all flocculant except commercial CPAM showed a wide scope of pH application.

A Library of Quinoline-Labeled Water-Soluble Copolymers with pH-Tunable Fluorescence Response in the Acidic pH Region

A series of quinoline-labeled water-soluble copolymers, synthesized through free radical copolymerization of vinyl-modified quinoline derivatives with water-soluble monomers such as the nonionic N,N-dimethylacrylamide (DMAM), the anionic sodium 2-acrylamidomethylpropanesulfonate (AMPSNa), and the cationic methacrylamidopropyltrimethylammonium chloride (MAPTAC), are investigated in the present work. As a result of the protonization/deprotonization equilibrium of the quinoline unit, the optical properties (absorption and, more important, emission of light) of these copolymers are controlled by the pH of the surrounding environment. In fact, the emitted light of the quinoline group changes from blue to green upon decreasing pH. It is shown that this pH-controlled color change can be tuned by the nature of the polymer chain (anionic, nonionic, or cationic) or the existence of substituents (such as cyanophenyl or perfluorophenyl groups), giving rise to a library of pH-responding quinoline-labeled materials tha...

Selective co-deposition of anionic silica particles at hydrophobic surfaces from formulations of oppositely charged polymers and surfactants

The surface-selective surface deposition of anionic hydrophilic silica particles from aqueous polymer–surfactant formulations was investigated by in-situ null-ellipsometry. The formulations, with or without silica particles, contained anionic sodium dodecylsulfate (SDS) and a cationic polymer, cationic hydroxyethyl cellulose (cat-HEC) or a copolymer of acrylamide and methacrylamidopropyl trimethylammonium chloride (AAm/MAPTAC). Surface deposition from the formulations onto model surfaces of either anionic hydrophilic, or hydrophobized, silica was induced by controlled dilution of the formulations into the coacervation region, and was monitored with time by ellipsometry. The dilution simulated a rinsing process in a typical application. In all cases a steady-state surface layer remained after extensive dilution. An enhanced deposition from the silica-containing formulations was found on the hydrophobized silica surface, indicating a substantial co-deposition of silica particles. Much less co-deposition, or none at all, was found on hydrophilic silica. The opposite trend, enhanced co-deposition on hydrophilic silica, was previously found in similar experiments with hydrophobic silicone oil droplets as co-deposants (Clauzel et al., 2011). The amphiphilic cationic polymers evidently favor a “mismatched” co-deposition of anionic particles to hydrophobic surfaces, or vice versa. The findings suggest a strategy for surface-specific delivery of particles to surfaces.

Cationic highly alcohol-swellable gels: synthesis and characterization

Cationic alcogels (alcohol-absorbing gels) based on acrylamide and methacrylamidopropyltrimethyl ammonium chloride (MAPTAC) were synthesized using solution polymerization in the presence of ammonium persulfate as an initiator and poly(ethylene glycol) diacrylate as a crosslinking agent. The swelling capacities of the gels in alcohols (i.e., methanol and ethanol) were investigated. The swelling capacities of the alcogels increased with increasing MAPTAC content, and the prepared gels had the ability to absorb up to 105.5 g/g methanol and 73.3 g/g ethanol, respectively. An ability to absorb more than 100 g/g of alcohol was only rarely observed. According to the results of rheological studies, the storage moduli of the ethanol-swollen gels were higher than those of the methanol-swollen gels, and enhancing the MAPTAC content caused the storage moduli of the gels to increase. Thermomechanical analysis was carried out to characterize the organogels. The values for the glass transition temperature (T g) implied that the structural rigidity of the acrylamide homopolymer is higher than that of the poly(MAPTAC), which indicates that the presence of the MAPTAC units softens the system. The DMTA results showed that the intensity of the tanδ peak in the matrix region decreased with increasing MAPTAC content. Thus, acrylamide units are better than MAPTAC units at damping dynamic forces, which can be attributed to the greater chain mobility of acrylamide.

Swelling equilibrium of hydrogels of (N-isopropyl acrylamide + anionic and cationic comonomers) in aqueous solutions of sodium chloride: Experimental results and modeling

Experimental results are reported for the swelling equilibrium of some ionic hydrogels consisting of N-isopropyl acrylamide (N-IPAAm) and one or two comonomers – the anionic monomer 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and/or the cationic monomer 3-(methacrylamido)propyl trimethylammoniumchloride (MAPTAC) – in water and in aqueous solutions of sodium chloride at 298K. The degree of swelling of such ionic hydrogels increases with the net charge (i.e., the difference in the mole fractions of anionic and cationic comonomers) as well as with the charge density (i.e. the mole fraction of a single comonomer). The mole fraction of a single comonomer was varied between 0 and 0.05. The (absolute) difference between the mole fractions of the anionic and cationic comonomers was varied between 0 and 0.03. Two characteristic transitions in the degree of swelling of the hydrogels were observed when sodium chloride is added to the coexisting liquid phase. The first transition depicts the conversion of the ionic comonomer into the neutral state. In that transition the degree of swelling of a charged ionic hydrogel reduces to the degree of swelling of a nonionic hydrogel. For the investigated hydrogels, that transition occurs when the mass fraction of NaCl in the coexisting aqueous phase is increased beyond approximately 5×10−5. The second transition occurs at much higher sodium chloride mass fractions (around 5×10−3). In that transition the hydrogel collapses, i.e., that transition resembles the phase transition observed when non-ionic N-IPAAm hydrogels are dissolved in aqueous solutions of sodium chloride.The experimental results for the degree of swelling are quantitatively described by a thermodynamic framework that combines an expression for the Gibbs energy of a liquid phase (a chemical reactive, aqueous electrolyte solution of the non-crosslinked polymer chains) with an expression for the Helmholtz energy of an elastic network (that accounts for the crosslinking effects).