Equilibrium Swelling and Solute Diffusion Characteristics of Poly (Methacrylic Acid co-Poloxamer) Hydrogels

Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.

CONFORMATIONAL CHARACTERISTICS OF POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID)

A full-relaxation optimization of molecule and the Dreiding force field are employed to obtain the geometry parameters and the conformational energy surfaces of meso or racemic dyad of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Three different carbonyl-bond orientations of side-groups resulted in the differences in depth of potential wells in their energetic contours for a meso or a racemic dyad. These discrepancies are interpreted as a result of various fine structures corresponding to grid search conformations as well as thereby different interactions. The analysis on the most stable conformations of PMAA confirmed that the ester groups are nearly perpendicular to the plane defined by the two adjacent skeletal bonds but may possibly change their relative orientations to meet the requirement of lower energy during the conformational state transition. For each polymer, two global energy maps of a meso and a racemic dyad were finally constructed from the superposition of energy data for the three kinds of side-group orientations by the Boltzmann factors. From an ensemble average, the proposed scheme with three rotational isomeric states (RIS) allowed us to access the experimentally unperturbed dimensions of PAA chain via the configurational statistical mechanics. Although the calculation was based on the short-range, local interactions, it was interested to note that the experimental characteristic ratios just fell within the range calculated for atactic chains.

Nitroxide-Mediated Photo-Controlled/Living Radical Polymerization of Methacrylic Acid

The photo-controlled/living radical polymerization of methacrylic acid (MAA) was performed at room temperature by irradiation with a high-pressure mercury lamp using azo initiators and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate (tBuS) as the accelerator. Whereas the bulk polymerization yielded polymers with a bimodal molecular weight distribution in both the absence and presence of tBuS, the solution polymerization in methanol produced unimodal polymers with the molecular weight distribution of 2.0 - 2.3 in the presence of tBuS. The molecular weight distribution of the resulting poly (MAA) decreased with an in- crease in tBuS. The dilution of the monomer concentration also reduced the molecular weight distribution. The use of the initiator with a low 10-h half-life temperature also effectively controlled the molecular weight. The livingness of the polymerization was confirmed by obtaining linear increases in the first-order conversion versus time, the molecular weight versus the conversion, and the molecular weight versus the reciprocal of the initiator concentration.

Highly efficient Rod-shape Poly(methacrylic acid-co-styrene-codivinylbenzene)High-performance Liquid Chromatographic Column

A highly efficient copolymer (methacrylic acid - co - styrene - divinylbenzene) in situ making high-performance liquid chromatographic column was prepared and evaluated. The column efficiency calculated in terms of height equivalent to a theoretical plate was 25 mu m and rapid separations of small molecules such as substituted aromatic hydrocarbons and aromatic acids were achieved within five minutes.

PROPERTIES AND SYNTHESIS OF NEW SUPPORTS FOR IMMOBILIZATION OF ENZYMES BY COPOLYMERIZATION OF VINYLENE CARBONATE AND METHACRYLIC ACID

Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH = 6.0 similar to 7.0, vinylene carbonate (VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reverse-phase suspension polymerization and hydrophilic copolymeric supports were prepared. The properties of the supports were determined using trypsin and results show that the amount of enzymes coupled to the supports and the specific activity of immobilized trypsin are related to the content of VCA structure units, reaction time and concentration of enzyme solution, etc.

Swelling and Drug Release Characteristics of Poly （methacrylic acid-co-poloxamer） hydrogels

Poly (methacrylic acid-co-poloxamer) hydrogel networks were synthesized byfree-radical solution polymerization, and the dynamic swelling and in vitro release properties ofmodel drugs, dextromethorphan hydrobromide (DMP) and vitamin B_(12) (VB_(12)) were studied. Thesegels exhibited pH-dependant swelling and sustained drug release properties, and the water uptakerate and drug release rate in neutral or basic media were higher than that in acidic media. Theresults showed that the water uptake followed non-Fickian or zero order process in neutral or basicmedia, and the release of model drugs from hydrogels of appropriate composition was of zero orderkinetics over a period of several hours.

The Effect of Methacrylic Acid and Maleic Acid on the Isothermal Kinetics of Acrylic Acid Crosslinking Co-polymerization under Conventional and Microwave heating

The kinetics of free-radical crosslinking co-polymerization(FRCCP)of acrylic acid(AA)with both methacrylic acid(MA)(PAMA hydrogel)and maleic acid(MAL)(PAMAL hydrogel)was investigated under the conditions of isothermal conventional heating(CH)and under the conditions of microwave heating(MWH)with controlled cooling.The kinetics curves of FRCCP of PAMA and PAMAL hydrogels under the conditions of CH are described with the kinetics model of second order chemical reaction,whereas the kinetics curves under the conditions of CH are described with the kinetics model of Polany-Winger.It is proved that MWH leads to the changes in the rate of FRCCP and to the changes in the values of the kinetic parameters activation energy(Ea)and pre-exponential factor(lnA).It was found the existence of relationship between the values of the kinetic parameters calculated for MWH and CH for PAMA and PAMAL hydrogel synthesis process,which is well-known as compensation effect.The effect of MWH on the kinetics of FRCCP for PAMA and PAMAL hydrogel formation were explained by applying the model of activation by selective energy transfer(SET).The changes in kinetics model,rate of FRCCP and kinetics parameters,caused with the MWH can found wide application in designing novel technologies for obtaining polymers and for synthesis of polymers with novel physico-chemical properties.The suggested mechanism of activation for polymerisation under the conditions of MWH also enables development of novel reaction systems and technologies for polymers productions.

SOLID PHASE GRAFT COPOLYMERIZATION OF POLYPROPYLENE AND METHACRYLIC ACID

The solid phase graft copolymerization of polypropylene (PP) andmethacrylic acid (MAA) was investigated. benzoyl peroxide(BPO) wasused as initia- tor. The influence of the reactive time,concentration of initiator and monomer on degree of graft and meltflow index of graft copolymer(PP-MAA) was discussed. The effect ofgraft copolymer on mechanical properties of The glass fibre (GF)reinforced PP composites was also Studied. It is proved that graftcopolymer could obviously Increase the interfacial adhesive strengthbetween PP and GF.

Process design and economic analysis of methacrylic acid extraction for three organic solvents

In this work,a techno-economic study for the solvent based extraction of methacrylic acid from an aqueous solution is presented.The involved phase equilibrium calculations in process design are verified by measured experimental data.First,experiments are conducted with different solvent candidates to measure LLE(liquid–liquid equilibrium)data and to establish the effects of extraction temperature and dosage of solvent.Next,the binary interaction parameters for the UNIQUAC model to be used for equilibrium calculations are fine-tuned with measured data.Then,a process for the solvent based extraction of methacrylic acid recovery is designed and verified through simulation with the regressed UNIQUAC model parameters.The optimal configuration of the process flowsheet is determined by minimizing the total annualized cost.Among the three solvent candidates considered-cyclohexane,hexane and toluene-the highest efficiency and the lowest total annualized cost is found with toluene as the solvent.

Efficient and selective upcycling of waste polylactic acid into acetate using nickel selenide

The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

Synthesis,Characterization and Catalytic Application of H_3PW_(12)O_(40)/MCM-48 in the Esterification of Methacrylic Acid with n-butyl Alcohol

A novel environmental friendly catalyst, H3PW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of n-butyl methacrylate catalyzed by H3PW12O40/MCM-48 was studied with methacrylic acid and n-butyl alcohol as reactants. H3PW12O40/MCM-48 is an excellent catalyst for synthesizing n-butyl methacrylate and Keggin structure of H3PW12O40 kept unchanged after being impregnated on surface of the molecular sieve support. Effects of n（methacrylic acid）：n（n-butyl alcohol）, catalyst dosage, cyclohexane（water-stripped reagent） and reaction time on yields of the product were investigated. The optimum conditions have been found, that is, molar ratio of acid to alcohol is 1：1.6, mass ratio of catalyst used to the reactants is 0.5% and reaction time is 2.0 h. Under these conditions, the yield of n-butyl methacrylate can reach 93.7%.

Edaravone-loaded poly(amino acid) nanogel inhibits ferroptosis for neuroprotection in cerebral ischemia injury

Neurological injury caused by ischemic stroke is a major cause of permanent disability and death. The currently available neuroprotective drugs fail to achieve desired therapeutic efficacy mainly due to short circulation half-life and poor blood−brain barrier (BBB) permeability. For that, an edaravone-loaded pH/glutathione (pH/GSH) dual-responsive poly(amino acid) nanogel (NG/EDA) was developed to improve the neuroprotection of EDA. The nanogel was triggered by acidic and EDA-induced high-level GSH microenvironments, which enabled the selective and sustained release of EDA at the site of ischemic injury. NG/EDA exhibited a uniform sub-spherical morphology with a mean hydrodynamic diameter of 112.3 ± 8.2 nm. NG/EDA efficiently accumulated at the cerebral ischemic injury site of permanent middle cerebral artery occlusion (pMCAO) mice, showing an efficient BBB crossing feature. Notably, NG/EDA with 50 µM EDA significantly increased neuron survival (29.3%) following oxygen and glucose deprivation by inhibiting ferroptosis. In addition, administering NG/EDA for 7 d significantly reduced infarct volume to 22.2% ± 7.2% and decreased neurobehavioral scores from 9.0 ± 0.6 to 2.0 ± 0.8. Such a pH/GSH dual-responsive nanoplatform might provide a unique and promising modality for neuroprotection in ischemic stroke and other central nervous system diseases.

Synergism of Zinc Oxide/Organoclay-Loaded Poly(lactic acid) Hybrid Nanocomposite Plasticized by Triacetin for Sustainable Active Food Packaging

The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.

Removal of nickel(Ⅱ) from aqueous solutions using iminodiacetic acid functionalized polyglycidyl methacrylate grafted-carbon fibers

Iminodiacetic acid functionalized polyglycidyl methacrylate grafted-carbon fibers(PGMA-IDA/CFs) were prepared for Ni(II) removal from aqueous solutions. The effects of solution p H value, temperature and adsorption time were investigated. The maximum adsorption capacity of Ni(II) on PGMA-IDA/CFs is 0.923 mmol·L-1· g-1at pH 5.2 and 50 °C. Kinetic data indicate that the adsorption process matches the pseudo-second-order model and Elovich kinetic model. Thermodynamic data suggest that the adsorption process is endothermic spontaneous reaction.

A NEW METHOD FOR THE SYNTHESIS OF METHACRYLIC ACID FROM ISOBUTYRALDEHYDE

Isobutyraldehyde was used as starting material via three steps: oxidation, chlorination and dehydro-chlorination to yield methacrylic acid. The total yield of methacrylic acid is 49.7%.

Synthesis, characterization and catalytic application of H4SiW12O40/MCM-48 in the esterification of methacrylic acid with n-butyl alcohol

A novel environmental friendly catalyst, H4SiW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of n-butyl methacrylate catalyzed by H4SiW12O40/MCM-48 was studied with methacrylic acid and n-butyl alcohol as reactants. H4SiW12O40/MCM-48 was an excellent catalyst for the synthesis of n-butyl methacrylate and Keggin structure ofH4SiW12O40 kept unchanged after impregnated on surface of the molecular sieve support. Effects of n（methacrylic acid）： n（n-butyl alcohol）, catalyst dosage, cyclohexane （water-stripped reagent） and reaction time on the yields of the product were investigated. The optimum conditions have been found, that is, molar ratio of acid to alcohol is 1：1.5, mass ratio of catalyst used to the reactant is 1.5%, cyclohexane is 10 mL and reaction time is 1.5h. Under these conditions, the yield of n-butyl methacrylate can reach 73.2%.

Removal of manganese from waste water by complexation-ultrafiltration using copolymer of maleic acid and acrylic acid

Copolymer of maleic acid and acrylic acid （PMA-100）, combining with polyvinyl butyral （PVB） ultrafiltration membrane was used for the removal of Mn（II） from waste water by complexation-ultrafiltration. The carboxylic group content of PMA-100 and the rate of complexation reaction were measured. Effects of the mass ratio of PMA-100 to Mn（II） （n）, pH, background electrolyte, etc on the rejection rate （R） and permeate flux （J） were investigated. The results show that carboxylic group content of PMA-100 is 9.5 mmol/g. The complexation of Mn（II） with PMA-100 is rapid and completed within 5 min at pH 6.0. Both R and J increase with pH increasing in the range of 2.5-7.0, and R increases with the increase of n at pH 6.0 while J is little affected. The background electrolyte leads to the decrease of R, and CaCl2 has much greater effect on R than NaCl at the same ionic strength.

Study on the repairing effect of poly(N-vinylpyrrolidone-co-methacrylic acid)on permed or bleached damaged hair

The repairing effect of poly(N-vinylpyrrolidone-co-methacrylic acid)on permed or bleached damaged hair was studied.The combing and tensile strength of permed and bleached hair before and after treatment with the copolymer solution were tested,and the effects of the mass fraction of copolymer solution and immerseing time on the combing and tensile strength for permed or bleached damaged hair were investigated.The repair mechanism of permed or bleached damaged hair was also explored.The results show that when the immersing time is 3 hours,the tensile strength of the permed hair increases with the mass fraction of the copolymer solution Tensile strength within 0%-0.3%,but no obvious change is observed when250 Yield strength the mass fraction is over 0.3%.Therefore,the optimal mass 200 fraction of the copolymer solution for repairing the permed hair(cN/dtex)is 0.3%.Similarly,the optimal mass fraction of the copolymer 150strength/solution for repairing the bleached hair is 0.5%.Furthermore,the effects of immersing time on the tensile strength of the100Tensile damaged hair fibers were compared between the permed and90 bleached hair before and after treatment with the copolymer500.40.30.500.10.2 solution.Coincidentally,the optimal immersion time for permedw(P(NVP-co-MAA))/%or bleached damaged hair is both 2 hours.The tensile strength of the permed and bleached hair soaked in 0.3%and 0.5%copolymer solutions for 2 hours increases by 15.55%and 18.12%,respectively,compared to untreated hair.Through infrared spectroscopy analysis,it is found that the amide II band in hair fibers shifted to the blue after repair,with the wave number shift of 11.12 and 11.09 cm^(-1),which confirm the formation of hydrogen bonds in the hair samples.Additionally,the urea hydrogen bond disruption experiment demonstrates that urea does not disrupt the hydrogen bonds in untreated hair fibers,but prevents the formation of new hydrogen bonds in damaged hair fibers.It further validates that the improvement of the tensile strength of the copolymer treated damaged hair fibers is mainly due to the formation of hydrogen bonds.After treatment with the copolymer,the dry and wet combing friction decrease by 30.73%and 28.55%for the permed hair,and decrease by 28.55%and 24.83%for the bleached hairs,respectively.The scanning electron microscope shows that the copolymer can flatten the cuticle and fill the space between the raised cuticles.

Antimicrobial Expanded Polytetrafluoroethylene Film Prepared by 3-ray Radiation Induced Grafting of Poly（acrylic acid）

The simultaneous γ-ray-radiation-induced grafting polymerization of acrylic acid on ex- panded polytetrafluoroethylene （ePTFE） film was investigated. It was found that the degree of grafting （DG） of poly（acrylic acid） （PAA） can be controlled by the monomer concentration, absorbed dose, and dose rate under an optimal inhibitor concentration of [Fe2＋]=18 mmol/L. SEM observation showed that the macroporous structure in ePTFE films would be covered gradually with the increase of the DG of PAA. The prepared ePTFE-g-PAA film was im- mersed in a neutral silver nitrate solution to fabricate an ePTFE-g-PAA/Ag hybrid film after the addition of NaBH4 as a reduction agent of Ag＋ to Ag atom. SEM, XRD, and XPS results proved that Ag nanoparticles with a size of several tens of nanometers to 100 nanometers were in situ immobilized on ePTFE film. The loading capacity of Ag nanoparticles could be tuned by the DG of PAA, and determined by thermal gravimetric analysis. The quart- titative antibacterial activity of the obtained ePTFE-g-PAA/Ag hybrid films was measured using counting plate method. It can kill all the Escherichia coli in the suspension in 1 h. Moreover, this excellent antibacterial activity can last at least for 4 h. This work provides a facile and practical way to make ePTFE meet the demanding antimicrobial requirement in more and more practical application areas.