Comonomer Ratio Research Articles

Poly(ether-carbonate) based hydrogel with tunable mechanical strength and enhanced bioactivity prepared by Michael addition

Abstract Poly (ether-ester) based hydrogels have been broadly used as degradable biomaterials in drug delivery systems and tissue engineering. However, they were synthesized with uncontrollable mechanical properties and inert to most of the biological activities, such as cell adhesion and stem cell differentiation. Herein, we synthesized a water-soluble copolymer with poly (trimethylene carbonate-co-2-methyl,2-methylacrylate-bimethylene carbonate) (PTMAc) and poly(ethylene glycol)(PEG) blocks (PCE), in which the PTMAc segments provided free active double bonds and can be further conjugated with thiol-ended peptides to improve its cytocompatibility. Meanwhile, the extra double bonds were crosslinked by Michael addition, forming hydrogels with precisely controlled mechanical strength. The chemical structure and molecular weight of the synthesized PCE were characterized by 1H NMR and gel permeation chromatography (GPC). The composition of the PCEs was controlled by changing the feed ratios of 2-methyl,2-methylacrylate-bimethylene carbonate (Ac) comonomer (fAc). It was noted that when the ratio of comonomers to the macroinitiator PEG ([M]0/[I]0 = 18) and the ratio of DL-Dithiothreitol (DTT) to Ac ([thiol]/[Ac] = 1/1) were fixed, the storage moduli of PCE hydrogels increased from 2 kPa to 10 kPa and the gelation time decreased with increasing fAc. The pendant double bonds were easily conjugated with CRGD to promote the neurite sprouting and axonal extension from the dorsal root ganglion (DRG) neurons. Moreover, the weaker the hydrogel matrix (G′ = 0.2 kPa) was, the lower the axon extension length was, but the axon diameter became thicker. An increase in modulus is beneficial to axon extension (5 kPa), while a high modulus (10 kPa) is unfavorable. These results demonstrated that this novel poly(ether-carbonate) based hydrogel can be introduced as a suitable scaffold for fast and effective nerve regeneration.

Synthesis of novel composite membranes by in-situ intercalative emulsion polymerization for separation of aromatic-aliphatic mixtures by pervaporation

Abstract Sodium montmorillonite (NaMMT) clay was coated with copolymer of acrylonitrile and acrylic acid of different comonomer ratios by in situ intercalative emulsion polymerization in water. Both untreated clay and polymer coated clay was incorporated in polyvinyl alcohol (PVA) followed by its crosslinking with maleic acid to form several composite membranes. These membranes were characterized by XRD, FTIR, DTA-TGA, SEM, EDAX, TEM and DMA and the effect of these uncoated and polymer coated clays on sorption and pervaporation of benzene-cyclohexane mixtures through these composite membranes were studied. The polymer coated clay filled membranes showed much higher flux and separation factor for benzene than the unfilled or uncoated clay filled membranes. The results showed that the preferential sorption of aromatic benzene by the polar membranes contributed to high separation factor for benzene in pervaporation. The solvent coupling in sorption and pervaporation were studied. The feed molar ratios of acrylonitrile and acrylic acid, clay: copolymer wt. ratio and wt. % of clay in PVA were optimized with a central composite design (CCD) of response surface methodology (RSM). The polymer coated clay prepared with the copolymer containing 5:1 M ratio of acrylonitrile and acrylic acid and the clay: copolymer wt. ratio of 1:1 was incorporated in PVA and the filled PVA membrane containing 8 wt% of this coated clay showed the optimum flux (g/m2h) of 65.38, 85.34 and 168.56 and the optimum separation factor(−) of 187.96, 172.72 and 137.16 for a feed of 0.5, 8 and 50 wt % benzene, respectively which was concentrated to 50.2, 93.0 and 99.2 wt% benzene, respectively after pervaporation. Keywords: intercalation; polymer coated clay; emulsion polymerization; composite membrane; pervaporation; benzene-cyclohexane.

Novel Fluorene and Pyrrole Comprising Copolymers: Effect of Copolymer Feed Ratio on Electrochromic and Electrochemical Properties

Herein, synthesis of two homopolymers namely, poly-2,2′-(9,9-dioctyl-9h-fluorene-2,7-diyl)bisthiophene (PBT), poly-pyrrole-3-carboxylic acid (PP3CA) and fluorene and pyrrole comprising five novel copolymers (CoP1, CoP2, CoP3, CoP4, CoP5) were electrochemically synthesized. Each electrolytic solution was prepared with different monomer feed ratios to investigate the effect of comonomer ratio on electrochromic and electrochemical properties. After synthesis, homopolymers and copolymers were compared in terms of their electrochemical, spectroelectrochemical and colorimetry properties. The number of studies on electrochromic characterization of pristine P3CA group was limited in literature, hence in this study P3CA was electrochemically inserted into the polymer chain via copolymerization.CoP1 with 1:1 (BT: P3CA) monomer feed ratio exhibited the lower optical band gap and red shifted neutral state absorption compared to PP3CA, additionally light yellow color of PP3CA turned out to be multichromic for CoP1with the insertion of BT unit via electrocopolymerization.

Novel high Tg fully biobased poly(hexamethylene-co-isosorbide-2,5-furan dicarboxylate) copolyesters: Synergistic effect of isosorbide insertion on thermal performance enhancement

Here an effective solution for overcoming the low glass transition temperature (Tg) of poly(hexamethylene 2,5-furan dicarboxylate) (PHF), a fully biobased polyester derived from dimethylfuran-2,5-furan-dicarboxylate (DMFD) and 1,6-hexanediol (1,6-HD), is proposed that uses isosorbide (Is) as a bicyclic rigid diol comonomer. Incorporating this sugar-derived diol with a broad scope content (3–90 mol%) into PHF macromolecular chain, by melt polycondensation and using titanium (IV) isopropoxide (TTIP) catalyst, results in the synthesis of highly heat-resistive poly(hexamethylene-co-isosorbide-2,5-furandicarboxylates) copolyesters (PHIsF). The chemical structure and composition of the prepared 100% renewable resources-based materials were confirmed in detail by 1H NMR and FTIR spectroscopies. Random microstructures were obtained for PHIsF samples, when Is content exceeds 40 mol%. As revealed by Wide-Angle X-ray Diffraction (WAXD) patterns, increase of IsF content in the copolymers leads to amorphous materials. The latter exhibited an excellent thermal stability up to 360 °C and very variable Tg values oscillating from 10 to 135 °C depending on the comonomer ratio, in which it gradually increases with increasing of Is feed content. Results found herewith showed that the high stiff building block Is can be used as an effective control parameter to spectacularly enhance the thermal properties of polymers, particularly the glass transition temperature. Taking advantage of their features, PHIsF have the potential to serve as promising fully biobased amorphous materials for practical applications that demand high Tg values.

Tertiary Amine Methacrylate based Polymers as Corrosion Inhibitors in Double Distilled Water. Part I

In the current study, the inhibitive performances of tertiary amine methacrylate based water soluble diblock copolymers on the corrosion behavior of AISI 304 stainless steel were investigated in double distilled water (DDW, at pH 7.6) using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and inductively coupled plasma optical emmision spectrometry (ICP OES) methods. Related diblock copolymers were poly[2-(dimethylamino)ethylmethacrylate] (PDMA), poly[2-(diethylamino)ethylmethacrylate] (PDEA), poly[2-(diisopropylamino)ethylmethacrylate] (PDPA) homopolymers and poly[2-(dimethylamino)ethylmethacrylate]-b-poly[methylmethacrylate] (PDMA-b-PMMA), poly[2-(diethylamino)ethylmethacrylate]-b-poly[methylmethacrylate] (PDEA-b-PDMA) and poly[2-(diisopropylamino)ethylmethacrylate]-b-poly[2-(dimethylamino)ethylmethacrylate] (PDPA-b-PDMA). Diblock copolymers having different molecular weight and different comonomer ratios. Polarisation curves indicated that all the studied polymers were acting as a mixed type inhibitors. All electrochemical measurements showed that inhibition efficiencies increased with an increase in the inhibitor concentration. It was determined that the increase of inhibitor efficiency by concentration resulted from the adsorption of polymers to metal surface, and the adsorption fitted to Langmuir adsorption equation. Adsorption equilibrium constant (Kads) and free energy of adsorption(ΔGads), which were thermodynamic parameters of adsorption were calculated by benefiting from the drawn adsorption isotherms. The variation in inhibitive efficiency mainly depended on the type and the nature of the substituents present in the inhibitor molecule and also depended on the molecular weight of the inhibitors. The best inhibition in DDW showed VB207 diblock copolymer. Surface images obtained with SEM, EDX and AFM methods, determined by verifying these results that inhibitors decreased the dissolution of metal, and prevented the corrosion.

Heterogeneous palladium SALOPHEN onto porous polymeric microspheres as catalysts for heck reaction

Abstract Catalysts based on porous polymeric microspheres were prepared from N,N′-Bis(3,3′-allyl-salicylidene)-o-phenylenediamine Pd(II) (PdAS) metallo-monomer, styrene (STY), and divinylbenzene (DVB) as co-monomers. The effects of the STY/PdAS mass ratio of co-monomers were investigated to synthesize the optimal catalyst. All the prepared materials were characterized by scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, inductively coupled plasma optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), solid-state diffuse-reflectance UV Vis (DRS UV-Vis) spectrometry, and X-ray photoelectron spectroscopy (XPS). Increasing the PdAS content from 1 to 5 wt%, based on the mass feed of monomers, produced well-defined spherical polymer resins with particle diameters of ~200 μm and high surface areas (>500 m2/g). XPS spectra shown a unique Pd2+ signal associated with the PdAS complex immobilized on a porous resin matrix. The catalytic performances of porous polymer microspheres were evaluated for Heck reaction between iodobenzene and methyl acrylate to produce methyl cinnamate, giving up to 100 % selectivity for the trans-isomer. The resin with 5 wt% PdAS showed the best catalytic activity in methyl cinnamate synthesis. Finally, the best catalytic system was evaluated in octinoxate production producing the target product with the same levels of conversion and selectivity for trans-isomer as was detected for methyl cinnamate synthesis.

Selective adsorption of cationic dyes from colored noxious effluent using a novel N-tert-butylmaleamic acid based hydrogels

Abstract The present research offers an innovative cyclic approach to cleaning colored water of toxic dyes due to the increased need for pure and safe water. Novel anionic hydrogels were fabricated via free radical copolymerization method in the presence of acrylamide or 2-hydroxyethyl methacrylate as neutral comonomer and N-tert-butylmaleimic acid as anionic monomer with the addition of N , N ′-methylenebisacrylamide as cross-linker. Hydrogels were examined for morphology and chemical structure using SEM and FTIR analyses. The swelling and adsorption behavior of the hydrogels with different molar ratios were examined. The parameters affecting the adsorption of the model dyes of CV and MB onto the hydrogel were investigated such as initial concentration of dye, various comonomer ratios, dose of hydrogel, and temperature. The adsorption behavior was consistent with the Langmuir isotherm model. Also, the thermodynamic analysis and Dubinin-Radushkevich isotherm model revealed that the adsorption of the dyes onto hydrogels was applicable in a wide temperature range as well as with physical and weak chemical interactions. TBMAC-based hydrogels were found to be a cost-effective prospective candidate with great regeneration efficiency and selectivity to be used as an adsorbent to effectively remove hazardous dyes from industrial waste.

Noncovalent Hydrogen Bonds Tune the Mechanical Properties of Phosphoester Polyethylene Mimics.

Polyethylene mimics of semicrystalline polyphosphoesters (PPEs) with an adjustable amount of noncovalent cross-links were synthesized. Acyclic diene metathesis copolymerization of a phosphoric acid triester (M1) with a novel phosphoric acid diester monomer (M2) was achieved. PPEs with different co-monomer ratios and 0, 20, 40, and 100% of phosphodiester content were synthesized. The phosphodiester groups result in supramolecular interactions between the polymer chains, with the P–OH functionality as an H-bond donor and the P=O group as an H-bond acceptor. A library of unsaturated and saturated PPEs was prepared and analyzed in detail by NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, thermogravimetry, rheology, and stress–strain measurements. The introduction of the supramolecular cross-links into the aliphatic and hydrophobic PPEs showed a significant impact on the material properties: increased glass-transition and melting temperatures were observed and an increase in the storage modulus of the polymers was achieved. This specific combination of a flexible aliphatic backbone and a supramolecular H-bonding interaction between the chains was maximized in the homopolymer of the phosphodiester monomer, which featured additional properties, such as shape-memory properties, and polymer samples could be healed after cutting. The P–OH groups also showed a strong adhesion toward metal surfaces, which was used together with the shape-memory function in a model device that responds to a temperature stimulus with shape change. This systematic variation of phosphodiesters/phosphotriesters in polyethylene mimics further underlines the versatility of the phosphorus chemistry to build up complex macromolecular architectures.

Synthesis and Physico-chemical Properties of (Co)polymers of 2-[(2E)-1-methyl-2-buten-1-yl]aniline and Aniline

A new soluble polymer on 2-[(2E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis have been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, as well as spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline has been carried out. The substituent introduced into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomer ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyaniline fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher the oxidation potential, the wider the band gap (ranging from 2.00 to 2.15). The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5–35.7 × 106 nSm.

Analysis of Sorption and Permeation of Acetonitrile–Water Mixtures through Nanoclay-Filled Copolymer Membranes

Several hydrophilic membranes were prepared by solvent casting from filled copolymers. These filled copolymers were synthesized by free radical polymerization of acrylonitrile (AN) and N-vinylpyrrolidone (NVP) monomers in different comonomer ratios (AN/NVP) in the presence of a nanosized clay. The membrane polymers were analyzed by NMR, Fourier transform infrared spectroscopy, X-ray diffraction, differential thermal and thermogravimetric analyses, scanning electron microscopy, mechanical properties, and dynamic mechanical analysis for characterization of its structural configuration, functionalities, copolymer composition, distribution of clay in the copolymer, and the strength and stability of the membrane under dynamic and thermal stress. The sorption and pervaporation of acetonitrile–water mixtures through these membranes were studied at varied copolymer compositions, mass % of clay, feed concentrations of water, and feed temperatures. Sorption data were analyzed by binary and ternary solvent/membrane ...

Influence of Concentrations of Methacrylate and Acrylate Monomers on the Properties of Fiber Reinforced Polymethyl Methacrylate Denture Base Materials

Abstract The study aimed to evaluate the effects of adding different concentrations of 2 hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), ethyl methacrylate (EA) and isobutyl methacrylate (IBMA) monomers on the structural, thermal and mechanical properties of a fiber reinforced heat-polymerized acrylic resin. For each test, 126 acrylic resin specimens were fabricated and divided into 6 groups with 7 specimens each. One group was the control group, the other one is a fiber reinforced group and others were the test groups, which were formed according to the different concentrations of monomers. 6 mm length, and the weight ratio of 3% short glass fibers are added to acrylic powder polymerized by heating. The 2%, 5%, 10%, at 20 % ratios of different comonomers added to a monomer of MMA are composed of copolymer structures. Flexural strength was assessed with a three-point bending test using a universal testing machine. Impact strength testing was conducted using an impact test machine by the Charpy method. The analysis of the connection between acrylic resin and fiber by SEM and structural changes in the acrylic resin was investigated by FTIR spectroscopy. Data analyses using analysis of Kruskal-Wallis and Mann-Whitney U tests (α=0.05) significant difference tests showed that adding 2%, 5% HEMA and IBMA monomers significantly increased the flexural and impact strength compared to the control, only fiber and others group (P< 0.05). It is observed that the process of adding low concentration of HEMA and IBMA monomers improved certain mechanical properties of fiber reinforced with polymethylmethacrylate.

Crosslinked Organosilicon-Acrylate Copolymer Moisture Barrier Thin Film Fabricated by Initiated Chemical Vapor Deposition (iCVD)

Crosslinked organosilicon-acrylate copolymer thin film with desired chemical composition was successfully fabricated by a simply modified initiated chemical vapor deposition (iCVD) process. Unlike the conventional iCVD copolymerization process, in our novel process, comonomers were injected together as one gas phase into the polymerization chamber from miscible liquid comonomer mixture. 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA) were used as the comonomers and tert-butyl peroxide was used as the initiator. From Fourier transform infrared (FTIR) spectra and solvent resistance test, we clearly confirmed that the crosslinked copolymer thin film with desired chemical composition could be obtained by controlling only the mixing ratio of liquid comonomers. It is expected that crosslinkable V4D4 organosilicon moiety provides hydrophobic moisture barrier property and CHMA acrylate moiety provides mechanical flexibility and better adhesion. We observed a certain level of moisture blocking capability of the copolymer thin film, implying potential application of the crosslinked organosilicon-acrylate copolymer thin film as flexible polymer buffer layer in organic/inorganic or metal oxide hybrid moisture barrier for flexible display or electronic devices.

Cross-Linked Ionomer Gel Separators for Polysulfide Shuttle Mitigation in Magnesium–Sulfur Batteries: Elucidation of Structure–Property Relationships

Cross-linked ionomer networks of varying poly(ethylene glycol) diacrylate cross-linker chain length, ionic comonomer chemistry, and comonomer ratio have been studied for their use as polysulfide shuttle inhibiting separators in magnesium–sulfur (Mg–S) batteries. Through the use of X-ray scattering, polysulfide diffusion experiments, conductivity measurements, and Mg–S cell cycling, it was determined that inclusion of tethered anions in polymer networks mitigates the polysulfide shuttle effect. Polysulfide crossover through networks into a bulk electrolyte can be reduced by absorption into the polymer gel, steric rejection, and electrostatic rejection, with the predominance of these mechanisms dictated by polymer composition and structure. The best network composition allowed an initial Mg–S cell discharge capacity of 522 mAh/g compared to a discharge capacity of 365 mAh/g using a literature standard glass fiber separator. The ionomer cell saw 67% capacity retention after three cycles, whereas the glass fi...

Crystalline CO2 -Based Aliphatic Polycarbonates with Long Alkyl Chains.

Carbon dioxide (CO2 ) is an easily available, renewable carbon source and can be utilized as a comonomer in the catalytic ring-opening polymerization of epoxides to generate aliphatic polycarbonates. Dodecyl glycidyl ether (DDGE) is copolymerized with CO2 and propylene oxide (PO) to obtain aliphatic poly(dodecyl glycidyl ether carbonate) and poly(propylene carbonate-co-dodecyl glycidyl ether carbonate) copolymers, respectively. The polymerization proceeds at 30°C and high CO2 pressure utilizing the established binary catalytic system (R,R)-Co(salen)Cl/[PPN]Cl. The copolymers with varying DDGE:PO ratios are characterized via NMR, FT-IR spectroscopy, and SEC, exhibiting high molecular weights between 11400 and 37900 g mol-1 with dispersities (Ð=M w /M n ) in the range of 1.37-1.61. Copolymers with T g s of -11°C or T m s from 5 to 15°C and thermal decomposition >200°C depending on the comonomer ratio, are obtained as determined by differential scanning calorimetry/TGA.

Synthesis of Well-Defined Dihydroxy Telechelics by (Co)polymerization of Morpholine-2,5-Diones Catalyzed by Sn(IV) Alkoxide.

Well-defined dihydroxy telechelic oligodepsipeptides (oDPs), which have a high application potential as building blocks for scaffold materials for tissue engineering applications or particulate carrier systems for drug delivery applications are synthesized by ring-opening polymerization (ROP) of morpholine-2,5-diones (MDs) catalyzed by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane (Sn(IV) alkoxide). In contrast to ROP catalyzed by Sn(Oct)2 , the usage of Sn(IV) alkoxide leads to oDPs, with less side products and well-defined end groups, which is crucial for potential pharmaceutical applications. A slightly faster reaction of the ROP catalyzed by Sn(IV) alkoxide compared to the ROP initiated by Sn(Oct)2 /EG is found. Copolymerization of different MDs resulted in amorphous copolymers with T g s between 44 and 54 °C depending on the molar comonomer ratios in the range from 25% to 75%. Based on the well-defined telechelic character of the Sn(IV) alkoxide synthesized oDPs as determined by matrix-assisted laser desorption/ionization time of flight measurements, they resemble interesting building blocks for subsequent postfunctionalization or multifunctional materials based on multiblock copolymer systems whereas the amorphous oDP-based copolymers are interesting building blocks for matrices of drug delivery systems.

Radical Polymerization and Kinetics of N,N-diallyl-N,N-dimethylammonium Chloride and Vinyl Ether of Monoethanolamine

N,N-diallyl-N,N-dimethylammonium chloride (DADMAC) and vinyl ether of monoethanolamine copolymer (VEMEA) was synthesized by radical polymerization in aqueous media using ammonium persulfate as initiator. Copolymers synthesis was carried out by varying monomer composition at low conversion level. The viscosity of high molecular weight products was measured in aqueous 1 M NaCl solution and it was increased with increasing DADMAC amounts in the copolymer due to increasing positive charge. The structure of the product was identified by FTIR, 1H, 13C-NMR spectroscopies and conductometric titration methods. We calculated monomer reactivity ratios with help of Finemann-Ross, Kelen-Tudos, and inverted Finemann-Ross methods. It was found that DADMAC is more reactive than VEMEA, therefore the amount of DADMAC in the copolymers always dominated regardless of the initial monomer ratio in solution and it was shown that the monomers are connected randomly in the polymer chain. The effect of various parameters such as monomer [M], initiator [I] concentrations, ratio of comonomers, etc. on polymerization was investigated systematically. So, the polymerization rate (Rp) equation was found to be Rp=k[M]2.6[I]0.6 where molar fractions of DADMAC and VEMEA was 90:10 and the temperature was 65 °C. Degree of polymerization was examined by using various monomers and initiator concentrations via the dilatometeric method. It was found that the polymerization rate increased directly with total monomer concentration and initiator content.

Template-free synthesis of tunable hollow microspheres of aniline and aminocarbazole copolymers emitting colorful fluorescence for ultrasensitive sensors

Conductive and fluorescent hollow micro/nanospheres have attracted great attention owing to their potential applications such as environmental clean-up, energy storage, sensors, and medical diagnosis. We report novel, tunable, and uniform hollow microspheres of conjugated poly(aniline-co-3-amino-9-ethyl-carbazole) (PAC) copolymer synthesized by a template-free method, namely a simple chemical oxidative copolymerization of aniline and 3-amino-9-ethyl-carbazole. The molecular structure of the copolymers has been systematically characterized by UV–vis, ATR-IR, Raman, and solid-state 13C cross-polarization magic angle spinning NMR spectroscopies. The particle size and properties including dispersibility, thermostability, electrical conductivity, fluorescence emission and its sensitive quenching of PAC hollow microspheres can be significantly controlled by simply optimizing feed comonomer ratios and reaction parameters such as acidic media and oxidants used. The formation mechanism of PAC hollow microspheres and their sensitively and selectively sensing properties toward nitro-based explosives and Cu(II) ions with the limit of detection down to 5 μM and 5 nM are demonstrated, respectively. In particular, the limit of detection for Cu2+ is superior as compared to literature reports.

Superswelling of Hydrogels Based on the Copolymer of Acrylamide and Methacrylic Acid

Weakly crosslinked hydrogels of copolymers of acrylamide and methacrylic acid are synthesized by radical polymerization in aqueous solution in a wide range of comonomer ratios. It is found that gels containing 20–40 mol % methacrylic acid are characterized by superswelling that exceeds the degree of swelling of homopolymer hydrogels by tens of times. The observed degree of swelling reaches 830, corresponding to an almost completely stretched conformation of subchains between network junctions. For dried hydrogel samples, the equilibrium degree of swelling is also maximal in the mentioned composition range; however, its maximum value is lower than the equilibrium degree of swelling for the initial samples. The possible reason behind the superswelling of hydrogels containing 20–40% units of methacrylic acid is an increase in ionization of network subchains. This hypothesis is proved by an increased sensibility of hydrogels of this composition to a change in the pH of a medium and the lowest values of the effective acidity constant determined by potentiometric titration for methacrylic acid units. The values of partial heat capacity of a gel polymer network are determined by calorimetry. These values are significantly higher than the heat capacities typical of vinyl polymers. This is evidence that the hydrophobic type of hydration predominates in the copolymers of acrylamide and methacrylic acid. The partial heat capacity reaches its maximum within the copolymer composition range corresponding to superswelling.

Fully-Zwitterionic Polymer-Supported Ionogel Electrolytes Featuring a Hydrophobic Ionic Liquid.

In this report, fully-zwitterionic (ZI) copolymer scaffolds for ionogel electrolytes have been synthesized via in situ photopolymerization using various molar ratios of 2-methacryloyloxyethyl phosphorylcholine (MPC) and sulfobetaine vinylimidazole (SBVI) within the hydrophobic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI). Depending on the chemical composition of the ZI scaffold, ionogel room temperature ionic conductivities are found to vary between 2.5 and 6.7 mS cm-1 at a fixed 20 mol % total polymer content. Compressive elastic moduli also exhibit a strong dependence on the co-monomer ratio, with values between 23 kPa and 11 MPa observed because of different degrees of ZI physical cross-linking. These results, together with NMR chemical shift analysis, suggest that the phosphorylcholine ZI group of MPC interacts more strongly with EMI TFSI, while SBVI prefers to self-aggregate and form dipole-dipole cross-links in the ionic liquid (IL). Self-diffusivity measurements of the EMI+ cations and TFSI- anions in both ionogel and ZI solution samples confirm that slower ion diffusion in MPC-containing systems is due to attractive zwitterion/IL interactions, and not merely reduced mobility in the presence of a polymeric scaffold. This work highlights the importance of relative zwitterion/IL and ZI dipole-dipole interactions on the properties of a novel class of fully-ZI polymer-supported ionogel electrolytes containing a hydrophobic IL suitable for future electrical energy storage applications.

Surface-Attached Poly(oxanorbornene) Hydrogels with Antimicrobial and Protein-Repellent Moieties: The Quest for Simultaneous Dual Activity.

By copolymerizing an amphiphilic oxanorbornene monomer bearing N- tert-butyloxycarbonyl (Boc) protected cationic groups with an oxanorbornene-functionalized poly(ethylene glycol) (PEG) macromonomer, bifunctional comb copolymers were obtained. Varying the comonomer ratios led to copolymers with PEG contents between 5–25 mol %. These polymers were simultaneously surface-immobilized on benzophenone-bearing substrates and cross-linked with pentaerythritoltetrakis(3-mercapto­propionate). They were then immersed into HCl to remove the Boc groups. The thus obtained surface-attached polymer hydrogels (called SMAMP*-co-PEG) were simultaneously antimicrobial and protein-repellent. Physical characterization data showed that the substrates used were homogeneously covered with the SMAMP*-co-PEG polymer, and that the PEG moieties tended to segregate to the polymer–air interface. Thus, with increasing PEG content, the interface became increasingly hydrophilic and protein-repellent, as demonstrated by a protein adhesion assay. With 25 mol % PEG, near-quantitative protein-adhesion was observed. The antimicrobial activity of the SMAMP*-co-PEG polymers originates from the electrostatic interaction of the cationic groups with the negatively charged cell envelope of the bacteria. However, the SMAMP*-co-PEG surfaces were only fully active against E. coli, while their activity against S. aureus was already compromised by as little as 5 mol % (18.8 mass %) PEG. The long PEG chains seem to prevent the close interaction of bacteria with the surface, and also might reduce the surface charge density.