Methacryloylamino)propyl]trimethylammonium Chloride Research Articles

Temperature-Adaptative Self-Oscillating Gels: Toward Autonomous Biomimetic Soft Actuators with Broad Operating Temperature Region.

Self-oscillating gel systems exhibiting an expanded operating temperature and accompanying functional adaptability are showcased. The developed system contains nonthermoresponsive main-monomers, such as N,N-dimethylacrylamide (DMAAm) or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or acrylamide (AAm) or 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC). The gels volumetrically self-oscillate within the range of the conventional (20.0°C) and extended (27.0 and 36.5°C) temperatures. Moreover, the gels successfully adapt to the environmental changes; they beat faster and smaller as the temperature increases. The period and amplitude are also controlled by tuning the amount of main-monomers and N-(3-aminopropyl) acrylamide. Furthermore, the record amplitude in the bulk gel system consisting of polymer strand and cross-linker at 36.5°C is achieved (≈10.8%). The study shows new self-oscillation systems composed of unprecedented combinations of materials, giving the community a robust material-based insight for developing more life-like autonomous biomimetic soft robots with various operating temperatures and beyond.

Use of polyvinyl alcohol-based cationic hydrogels modified with gold nanoparticles as drug and gene delivery systems with enhanced antibacterial properties

In this study, PVA/p(HEMA-co-MAPTAC) hydrogels were synthesized by redox polymerization using polyvinyl alcohol (PVA), 2-hydroxyethyl methacrylate (HEMA) and [3-(Methacryloylamino)propyl]trimethylammonium chloride (MAPTAC). In order to increase the antimicrobial activities of synthesized PVA/p(HEMA-co-MAPTAC) hydrogels, they were modified with Au nanoparticles. The swelling behavior of the synthesized hydrogels was investigated. Hydrogels were characterized by various techniques. The drug release studies of PVA/p(HEMA-co-MAPTAC) and PVA/p(HEMA-co-MAPTAC)@Au hydrogels were performed in PBS medium using Ribonucleic acid (RNA) as genetic material and sodium diclofenac (NaDc) as drug. It was determined that PVA/p(HEMA-co-MAPTAC) hydrogel held 91.5 mg/g RNA and 97.48 mg/g NaDc and released 28.32 mg/g RNA and 71.12 mg/g NaDc in PBS medium. Subsequently, PVA/p(HEMA-co-MAPTAC)@Au hydrogel adsorbed 87.46 mg/g RNA and 119.44 mg/g NaDc and released 18.96 mg/g RNA, 104.99 mg/g NaDc drug in PBS medium. Using the data obtained at the end of the release studies, the drug release kinetics of the hydrogels were examined. According to the Korsmeyer Peppas model, RNA release from hydrogels showed Fickian diffusion, while NaDc release showed non-Fickian diffusion behavior. The antibacterial and antifungal activities of the hydrogels were tested using gram-negative bacteria E. coli, gram-positive bacteria B. subtilis and a fungus species C. albicans.

Preparation and characterization of chemically cross-linked zwitterionic copolymer hydrogel for direct dye and toxic trace metal removal from aqueous medium

In this work, a zwitterionic copolymer hydrogel with adsorption affinity toward anionic dye and cationic trace metal was prepared by a free radical copolymerization of cationic ([3-(methacryloylamino)propyl] trimethylammonium chloride (MPTC)) and anionic (sodium 4-vinylbenzenesulfonate (SVBS)) monomers. Bis[2-(methacryloyloxy)ethyl] phosphate was used as a cross-linker and its effect on the adsorption properties of the prepared hydrogel was evaluated. The prepared materials were characterized by FTIR, XRD, SEM, EDX, and N2 adsorption at 77 K analysis. FTIR and EDX analysis demonstrated the successful preparation of poly(MPTC-co-VBS). XRD and SEM analysis showed that the poly (MPTC-co-VBS) is amorphous and has quasi-honeycomb morphology with large pores. Increasing the amount of the cross-linker enhanced the adsorption of direct blue 71 dye (DB71) and Pb(II) ions. The highest removal of DB71 and Pb(II) was achieved after 2 h using 1.5 g/L of poly(MPTC-co-VBS); however, the optimum solution pH was 3 for DB71 and 5 for Pb(II). The kinetics and isotherm studies illustrated that the surface of poly(MPTC-co-VBS) is heterogenous with small-sized homogenous pitches and the DB71 and Pb(II) adsorption onto poly(MPTC-co-VBS) is favorable. Finally, poly(MPTC-co-VBS) is more efficient in removing DB71 and Pb(II) from aqueous solutions than many other reported adsorbents.

Flexible Humidity Sensor Based on Au Nanoparticles/Organosilica-Containing Polyelectrolyte Composite

A novel flexible humidity sensor incorporating gold nanoparticles (Au NPs) and a trifunctional organosilica compound has been developed through the integration of sol–gel processing, free radical polymerization, and self-assembly techniques. The trifunctional organosilica was initially synthesized by modifying (3-mercaptopropyl)trimethoxysilane (thiol-MPTMS) with 3-(trimethoxysilyl)propyl methacrylate (vinyl-TMSPMA). Subsequently, a hydrophilic polyelectrolyte, [3(methacryloylamino)propyl]trimethyl ammonium chloride (MAPTAC), was grafted onto the MPTMS-TMSPMA gel. The Au NPs were assembled onto the thiol groups present in the MPTMS-TMSPMA-MAPTAC gel network. The compositional and microstructural properties of the Au NPs/MPTMS-TMSPMA-MAPTAC composite film were investigated utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The presence of thiol groups and mesoporous silica skeletons ensured the stability of the humidity-sensing film on the substrate under highly humid conditions, while the hydrophilic groups functioned as humidity-sensitive sites. This innovative humidity sensor demonstrated high sensitivity, acceptable linearity, minimal hysteresis, and rapid response time across a broad range of working humidity levels. Based on the complex impedance spectra analysis, hydronium ions (H3O+) were determined to govern the conductance process of the flexible humidity sensor.

Surface modification of graphene oxide for preparing self‐healing nanocomposite hydrogels

AbstractIn this work, graphene oxide (GO) and vinyl modified GO (V‐GO)‐based nanocomposite hydrogels with improved mechanical property and self‐healing ability have been synthesized and characterized. GO first was synthesized by modified Hummer's method using graphite powder and then functionalized with vinyl groups by using (3‐mercaptopropyl) trimethoxysilane (MPTS) via silanization method. The GO and V‐GO nanoparticles were characterized by FT‐IR, UV–vis spectroscopy, SEM, and dynamic light scattering technique (DLS). Hydrogels were obtained by in‐situ free‐radical polymerizations of acrylamide (AAm) and [3‐(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC) monomers in the presence of GO and V‐GO nanoparticles. The effects of the amount of GO and V‐GO on the gelation profile and viscoelastic characteristics of the hydrogels were studied. The pH‐responsive action, swelling behavior, and swelling kinetics of the hydrogels with various GO and V‐GO contents were also evaluated. The mechanical performance of nanocomposite cationic hydrogels prepared with GO and V‐GO nanosheets was compared to the neat AAm‐MAPTAC hydrogels. The self‐healing ability of the hydrogels were elucidated as a function of the amount of GO and V‐GO nanosheets bound to the polymer network by physical interactions and chemical cross‐links, respectively.

PLP-SEC Investigation of the Influence of Electrostatic Interactions on the Radical Propagation Rate Coefficients of Cationic Monomers TMAEMC and MAPTAC

The decisive role of counterions on the propagation mechanism in the radical polymerization of ionized monomers is comprehensively studied. Propagation rate coefficients, kp, were obtained for cationic monomers [2-(methacryloyloxyethyl)]trimethylammonium chloride (TMAEMC) and [3-(methacryloylaminopropyl)]trimethylammonium chloride (MAPTAC) in aqueous solution by pulsed-laser polymerization combined with size-exclusion chromatography over broad ranges of monomer concentration (1–40 wt %), temperature (5–90 °C), pH (2–12), and salts selected to provide a molar counterion concentration, ccounterion, between 0.05 and 3 mol·L–1. Both monomers behave similarly under conditions at which repulsive electrostatic interactions between a polymer chain and a reacting monomer dominate (ccounterion < 0.2 mol·L–1). The kp values increase linearly with ccounterion above this value due to screening of the repulsive interactions and follow the family behavior of nonionized methacrylate and methacrylamide monomers manifested by a higher kp for TMAEMC than for MAPTAC. The hydration of the polyelectrolyte chain is considered as an additional factor contributing to higher kp values for cationic TMAEMC at high ccounterion values compared to its nonionized analogue 2-dimethylaminoethyl methacrylate. The extensive set of kp data can be represented using average activation energies of 14.4 ± 2.7 and 14.7 ± 2.0 kJ·mol–1 for TMAEMC and MAPTAC, respectively, and a preexponential factor that increases with ccounterion. The batch polymerization of MAPTAC compared to that of TMAEMC reflects the differences in kp behavior for these monomers.

Development of a Tough, Self-Healing Polyampholyte Terpolymer Hydrogel Patch with Enhanced Skin Adhesion via Tuning the Density and Strength of Ion-Pair Associations.

Polyampholyte (PA) hydrogels have great potential for biomedical applications, owing to their high toughness and good self-recovery and self-healing (SELF) behavior in addition to their physical properties similar to human tissue. However, their implementation as practical biomedical skin patches or wearable devices has so far been limited by their insufficient transdermal adhesion strength. In this work, a new polyampholytic terpolymer (PAT) hydrogel with enhanced skin adhesion was developed using a novel and simple strategy that tunes the structure of ion-pair associations (IPAs), acting as cross-links, in the hydrogel via adding an extra neutral monomer component into the network without changing the total charge balance. The PAT hydrogels were synthesized by the terpolymerization of the neutral monomer N,N-dimethylacrylamide (DMAAm) (or 2-hydroxyethyl methacrylate (HEMA)) as well as the cationic monomer 3-(methacryloylamino) propyl-trimethylammonium chloride (MPTC) and the anionic monomer sodium p-styrenesulfonate (NaSS). Their IPA, which determines their network structure, was modulated by varying the feed concentration of the neutral monomer, Cnm. An increase of Cnm within an optimized Cnm window (0.3-0.4 M) decreased the cross-linking density (strength and density of the IPAs) of the PAT hydrogels, reducing the softening temperature and Young's modulus, which increased compliance but maintained sufficient mechanical strength and thereby maximized the contact surface and enhanced skin adhesion. The DMAAm monomers, compared to the HEMA monomers, produced the higher skin adhesion of the PAT hydrogel, which was explained by the difference in their reactivity to the MPTC and NaSS. This study demonstrated this new method to develop the PAT hydrogels with excellent skin adhesion and biocompatibility while maintaining good toughness, compliance, and SELF behavior and the potential of the PAT hydrogels for biomedical skin patches and wearable devices.

Inhibitory effects of functionalized polycarboxylate retarder on aberrant thickening phenomena of oil well cement at high temperature

Aberrant thickening of cement slurry caused by polycarboxylate retarders mainly refers to abnormal gelation and thickening time reversal (TTR) when temperature reaches above 120 °C. These phenomena would directly jeopardize cementing operation and hinder the application of polycarboxylate retarders in oil and gas exploitation. Herein, two functionalized polycarboxylate retarders were synthesized to overcome the challenges in complex conditions. The incorporation of isoprenyl oxy poly(ethyleneglycol) ether (TPEG) and [3-(methacryloylamino) propyl] trimethyl ammonium chloride (MAPTAC) was capable of preventing unfavorable “crosslinking and chelation” reaction between cement grains and polymer, thereby avoiding abnormal gelation. It was also found that the hydrophobic association behavior of long side chain in TPEG could cause the gradual release of carboxyl groups at elevated temperature, which was unfavorable for TTR inhibition. When the TPEG was replaced by N-Vinyl-2-Pyrrolidinone (NVP), its retarding effect gradually weakened when temperature rose from 130 °C to 150 °C, and excellent inhibition of TTR was achieved.

Removal of anionic dyes from aqueous media by using a novel high positively charged hydrogel with high capacity

Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N′-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of qmax are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.

Kinetics and Modeling of Aqueous Phase Radical Homopolymerization of 3-(Methacryloylaminopropyl)trimethylammonium Chloride and its Copolymerization with Acrylic Acid

The radical homopolymerization kinetics of 3-(methacryloylaminopropyl) trimethylammonium chloride (MAPTAC) and its batch copolymerization with nonionized acrylic acid (AA) in aqueous solution are investigated and modeled. The drift in monomer composition is measured during copolymerization by in situ NMR over a range of initial AA molar fractions and monomer weight fractions up to 0.35 at 50 °C. The copolymer becomes enriched in MAPTAC for monomer mixtures containing up to 60 mol% MAPTAC, but is enriched in AA for MAPTAC-rich mixtures; this azeotropic behavior is dependent on initial monomer content, as electrostatic interactions from the cationic charges influence the system reactivity ratios. Models for MAPTAC homopolymerization and AA-MAPTAC copolymerization are developed to represent the rates of monomer conversion and comonomer composition drifts over the complete range of experimental conditions.

Polarity of Cationic Lignin Polymers: Physicochemical Behavior in Aqueous Solutions and Suspensions.

The structure of cationic monomers can significantly impact the polarity of lignin after polymerization. Cationic hydrolysis lignin (CHL) polymers were produced by polymerizing hydrolysis lignin (HL) with [3-(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC) or [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (METAC). The METAC monomer has an oxygen atom, with larger electronegativity, in its molecular structure, whereas the MAPTAC monomer contains a nitrogen atom, as well as an extra nonpolar CH2 group, facilitating investigation into the effects of the polarity of CHLs on their physicochemical performance in an aqueous system. CHL polymers are analyzed and their interactions with clay particles are determined in colloidal systems. CHLs are designed to have similar charge densities (2.1-2.2 mmol g-1) and molecular weights (55000-60000 g mol-1 ). The hydrodynamic radius (Hy) and radius of gyration, (Rg) of HL-METAC are larger than those of HL-MAPTAC, implying a more 3-dimensional structure of HL-METAC in aqueous solution. The stability ratio of kaolin particles affirms the better performance of HL-METAC in comparison to HL-MAPTAC, which reflects the better flocculation efficiency of HL-METAC. The results also reveal that salt and urea aqueous solutions affect the Hy, Rg, and configuration of CHL polymers, which alters the flocculation efficiency of HL-METAC and HL-MAPTAC polymers in kaolin suspensions.

Quantitative Insights into the Effects of Post-Cross-Linking on Physical Performance Improvement and Surface-Cracking Healing of a Hydrogel.

We report a post-cross-linking protocol that can improve the mechanical properties, freezing resistance, and fracture energies of a covalent cross-linking hydrogel and can also enable its surface-cracking healing. We design a covalent cross-linking reaction based on 3-(methacryloylamino) propyl-trimethylammonium chloride (MPTC) and sodium acrylate (SA) to give rise to a PMPTC@PSA model hydrogel. After post-cross-linking treatment, the mechanical stress is improved by 9.0-fold, accompanied by a 3.5-fold improvement in elongation; the freezing resistance is increased by 2.5-fold, which is reflected by the stretchability improvement at -35 °C. In addition, the fracture energy increased from 266 to 4686 J/m2, an ∼17-fold improvement. Importantly, a surface-cracking hydrogel can be healed through the post-cross-linking treatment that enables the healing efficiency to approach 100% in terms of mechanical modulus and >81% in terms of maximum mechanical stress. This protocol is expected to provide a new option for physical performance improvement and crack healing of hydrogels in soft actuator, sensing device, and robotic applications.

Antimicrobial cationic acrylate-based hybrid coatings against microorganism contamination

Microorganism contamination on substrate surfaces is arousing increasingly concern as a serious health issue. In this study, we described fabricating antimicrobial cationic acrylate-based composite and investigating it as antimicrobial coatings of interior walls in buildings. Firstly, utilizing 3-(methacryloylamino) propyltrimethyl ammonium chloride (MPAC) and acrylates (BA, MMA) as monomers, a novel antimicrobial cationic acrylate-based copolymers (PAMs) was synthesized from surfactant-free emulsion polymerization (SfEP). The synthesis conditions, structures and physical properties of copolymers (PAMs) and its film (PAMs-F) were investigated through FT-IR, SEM, TEM and scratch test, etc. The results revealed that 6 % of MPAC and 0.5 % of KPS enabled the film-forming properties and enhanced conversion rate of PAMs, as well as endowed PAMs-F with significant antimicrobial activity. Furthermore, the PAMs based coating (PAMs-C) was prepared by PAMs and inorganic fillers. And the antimicrobial activity of PAMs-F and PAMs-C was measured, the effects of cationic monomer and nano-TiO2 were also investigated. The results indicated that PAMs-C was able to use to protect the building interior wall from microbial contamination.

Effect of ionomer/multiplet formation on mechanical properties and ascorbic acid release behavior of PNIPAAm hydrogels copolymerized by DMAEMA, DMAPMAAm and MAPTAC

Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels containing N-[3-(N,N-dimethylamino)propyl]methacrylamide (DMAPMAAm), 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) as cationic monomers were cross-linked with N,N’-methylenebisacrylamide (BIS) and tetraallylammonium bromide (TAB). The swelling degrees, uniaxial compression moduli and L-ascorbic acid (L-AA) releases of these cationic PNIPAAm hydrogels synthesized in 1,4-dioxane were compared with the one prepared in distilled–deionized water (DDW) and in aqueous sodium hydroxide solution (0.1 N NaOH). P(NIPAAm-co-MAPTAC)/BIS and P(NIPAAm-co-DMAEMA)/BIS hydrogels at 37 °C in DDW and at 37 °C/pH 4 exhibited higher gel strengths and compressive moduli than all the others cross-linked and copolymerized with TAB and DMAPMAAm, respectively. All the observations indicated that the physical cross-linking points created by ionomer pairs of MAPTA+Cl− units and the hydrophobic contributions of ester groups in the DMAEMA units might be a reason of their improved mechanical properties in DDW at 37 °C. Further, the charge screening effect of chloride ions in the swelling medium at pH 4 also resulted in the improved compressive moduli compared to the ones in DDW. The water diffusion into/from all the copolymeric PNIPAAm hydrogels during the swelling/deswelling processes at 25 °C/37 °C in DDW and their L-AA releases at 37 °C in DDW also revealed the importance of these ionic and hydrophobic effects. Water transport through the ones cross-linked with TAB was controlled by non-Fickian process due to the repulsive forces between the quaternized ammonium groups on the chemical cross-links while in the case of P(NIPAAm-co-MAPTAC)/BIS, water transport followed Fickian diffusion because the multiplet formations behaved as additional cross-links. Furthermore, P(NIPAAm-co-MAPTAC)/BIS hydrogel due to the ionomer-multiplet transitions at 37 °C in DDW has exhibited less-Fick diffusion that resulted in a lower diffusion coefficient during the release of L-AA as compared to the others.

Polyurea-crosslinked cationic acrylate copolymer for antibacterial coating

A novel polyurea-crosslinked cationic acrylate copolymer (PUAM) with antibacterial activity, using 3-(methacryloylamino) propyl trimethyl- ammonium chloride (MPAC) as antibacterial functional monomer, had been successfully synthesized by via soap-free emulsion polymerization. The microscopic morphology analyses from SEM and TEM demonstrated that the resulting PUAM copolymer self-assembled into uniformly dispersed, nearly spherical nanoparticles, and its average diameter was close to 200 nm. The structure analyses consisted of FT-IR, TGA and some other basic performance tests revealed that the acrylate copolymer (PAM) was successfully combined with polyurea, and as expected, PUAM copolymer possessed high thermal stability and excellent mechanical properties. Antibacterial tests indicated that antibacterial monomer introduced here imparted PUAM copolymer emulsion with better dispersion stability and obvious antibacterial activity. Furthermore, the PUAM coating consisted of PUAM emulsion with nano-TiO2 and other inorganic fillers was also successfully prepared and presented excellent antibacterial activity and mechanical properties. It could be applied as antibacterial coating to prevent the undesirable accumulation of microorganisms on substrate surface.

Water-soluble nanoparticles from PEGylated linear cationic block copolymers and anionic surfactants

The water-soluble complexes formed between a set of positively charged linear block copolymers (BCPs) of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) with oppositely charged double-tail surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT), and biosurfactants (bile salts) containing hydrophilic steroid structure were studied using turbidimetric titration, steady-state pyrene fluorescence study, zeta-potential measurement, dynamic light scattering, and electron microscopy. These complexes do not precipitate in the entire range of compositions of the mixtures including stoichiometric compositions establishing their water solubility and potential usefulness. These BCPs were found to form water-soluble vesicles when mixed with a stoichiometric quantity of AOT and micelle-like loosely bound aggregates when mixed with bile salts at room temperature. The differential complex formation of the surfactants was due to the structural differences between bile salts and AOT.

Synthesis and characterization of a novel cationic hydrogel base on salecan-g-PMAPTAC

Salecan is a biological macromolecular and biocompatible polysaccharide that has been investigated for recent years. Herein, we report a novel cationic hydrogel fabricated by graft-polymerizing 3-(methacryloylamino)propyl-trimethylammonium chloride (MAPTAC) onto salecan chains. The obtained hydrogels were transparent, solid-elastic, macro-porous, ion-sensitive, and non-cytotoxic. The swelling ratios increased with salecan content, while mechanical strength does the opposite. Moreover, drug delivery test was studied as a potential application. Diclofenac sodium (DS) and insulin were selected as model drugs. Interestingly, in drug loading process, DS molecules exhibited highly affinity to these cationic hydrogels. Almost all the DS molecules in loading solution were absorbed and spread into the hydrogel. For drug release profiles, insulin-loaded hydrogel showed an initial rapid release and a sustained release. As a comparison, DS-loaded hydrogel exhibited a more sustained release profile. Results suggested salecan-g-PMAPTAC hydrogel could be a good candidate for anionic drug loading and delivery.

New approach for the fabrication of double-network ion-gel membranes with high CO2/N2 separation performance based on facilitated transport

A poly(methacryloylamino propyl trimethylammonium chloride)/poly(dimethylacrylamide) (PMAPTAC/PDMAAm) double-network (DN) ion-gel membrane containing triethyl(2-methoxymethyl)phosphonium indazole ([P222(1O1)][Inda]) was fabricated via a casting method, displaying excellent mechanical strength and high CO2 separation performance. Changes in the cross-linker loading of the PMAPTAC network were found to significantly impact the CO2 separation performance of the ion-gel membrane. For instance, as the cross-linker loading was decreased from 4 to 0.5mol.%, the CO2 permeability and CO2/N2 selectivity increased from 2254 to 7569 Barrer and from 130 to 210, respectively. The network structure and mechanical properties of the fabricated ion gels was also strongly dependent on the cross-linker loading of the PMAPTAC network, with excellent strength obtained at decreased loadings. The CO2 transport properties of the DN ion-gel membranes were substantially improved by increasing the [P222(1O1)][Inda] content, which was mainly attributed to two cooperative factors: (1) carrier content increase, resulting in a large driving force for the diffusion of the CO2-complex and (2) decrease of the polymer network content, resulting in lower diffusion resistance. The proportional enhancement of CO2 permeance with reducing ion-gel membrane thickness implied that diffusion is the rate-determining step of CO2 permeation.

Crack Blunting and Advancing Behaviors of Tough and Self-healing Polyampholyte Hydrogel

Recently, we have reported that polyampholytes, synthesized from free radical copolymerization of anionic monomer and cationic monomer, form physical hydrogels of high toughness and self-healing. The random distribution of the opposite charges forms ionic bonds of a wide distribution of strength. The strong bonds serve as permanent cross-links, imparting elasticity, whereas the weak bonds serves as reversible sacrificial bonds by breaking and reforming to dissipate energy. In this work, we focus on the rupture behaviors of the polyampholyte physical hydrogel, P(NaSS-co-MPTC), copolymerized from sodium p-styrenesulfonate (NaSS) and 3-(methacryloylamino)propyltrimethylammonium chloride (MPTC). Tensile test and pure shear test were performed at various stretch rates in the viscoelastic responses region of the material. Tensile test showed yielding, strain softening, and strain hardening, revealing the dually cross-linked feature of the gel. Pure shear test showed crack blunting at the notched tip and a large...

Preparation of amphoteric polycarboxylate superplasticizers and their performances in cementitious system

ABSTRACTA series of amphoteric polycarboxylate (PC) polymers were synthesized by radical copolymerization of acrylic acid (AA), [3‐(methacryloylamino) propyl] trimethylammonium chloride (MAPTAC) and ω‐methoxypolyoxyethylene methacrylate ester (MPEGMA). Cationic groups were introduced in to PC molecules with expectation of less retardation effect on cement hydration compared to the traditional anionic PC superplasticizers. The content of cationic groups in polymer was varied by changing the monomer ratio of MAPTAC to AA in the synthesis recipes. The structure of the synthesized amphoteric PCs was verified by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The performances of the amphoteric PCs were evaluated by measurement of flowability and zeta‐potential of cement pastes and adsorption amount of PC in cement pastes. Impacts of the PCs on cement hydration were studied by isothermal calorimetry. It is concluded that both anionic and cationic PC polymers can be effectively adsorbed onto the surface of cement particles and thus change the zeta potential of cement pastes. The adsorption amounts of the amphoteric PCs decrease with increasing content of cationic units. A proper incorporation of cationic units into PC polymers may lead to a higher fluidizing performance in fresh cement pastes. The amphoteric PC polymers with higher content of cationic units show less retardation effect on cement hydration and hence higher early strength of cementitious materials may be achieved by using amphoteric PCs with appropriated content of cationic units without losing their plasticizing efficiency. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41348.