Reaction Of Epoxy Groups Research Articles

Tailor-made magnetic nanocomposite with pH and thermo-dual responsive copolymer brush for bacterial separation

Rapid detection of pathogenic bacteria particularly in food samples demands efficient separation and enrichment strategies. Here, hydrophilic temperature-responsive boronate affinity magnetic nanocomposites were established for selective enrichment of bacteria. The thermo-responsive polymer brushes were developed by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide (NIPAm) and allyl glycidyl ether (AGE), followed by a reaction of epoxy groups, and incorporation of fluorophenylboronic acid. The physical and chemical characteristics of the magnetic nanocomposites were analyzed systematically. After optimization, S. aureus and Salmonella spp. showed high binding capacities of 32.14 × 106 CFU/mg and 50.98 × 106 CFU/mg in 0.01 M PBS (pH 7.4) without bacteria death. Bacterial bindings can be controlled by altering temperature and the application of competing monosaccharides. The nanocomposite was then utilized to enrich S. aureus and Salmonella spp. from the spiked tap water, 25% milk, and turbot extraction samples followed by multiplex polymerase chain reaction (mPCR), which resulted in high bacteria enrichment, and demonstrated great potential in separation of bacteria from food samples.

Eco-friendly colorization of textile originating from polydopamine nanofilm structural color with high colorfastness

Traditional textile dyeing industry usually use chemical pigments and dyes, which bring about a large amount of colored wastewater causing serious environmental pollution. Replacing the traditional high pollution dyeing methods to realize eco-friendly dyeing is very important to the textile dyeing industry, structural colorization maybe one of the most promising methods. In this study, a novel approach was proposed to fabricate eco-friendly coloration of textile originating from polydopamine (PDA) structural color nanofilm with high colorfastness. Four different bright colors were obtained by the polymerization of PDA nanofilm with different reaction times on cotton fabric. However, capillary tension during the formation of PDA nanofilm and weak interaction with fabric substrate resulted in cracking and poor colorfastness. The novel synthesis adhesive of poly (glycidyl methacrylate co-polyethylene glycol methyl ether methacrylate) containing reactive epoxy groups was used to avoid cracking and improve the colorfastness which would form covalent bond on the interface between structural color film and substrate. Therefore, crack-free PDA structural color nanofilm with high colorfastness on cotton fabric surface was obtained. This facile approach provide novel idea for eco-friendly dyeing different kinds of textiles with structural color boosting the cleaner dyeing in textile industrial field.

Dual Microcapsulation of an Environmentally‐Friendly‐Based Reactive Multifunctional Acrylated Epoxy Resin and Thiol by Internal Phase Separation Technique for Self‐healing Applications

In this research, the microcapsules were individually prepared via internal phase separation technique using reactive bio-based acrylated epoxidized soybean oil, AESO, and trimethylolpropane tris(3-mercaptopropionate), TMPMP as healing and curing agents respectively in PMMA shell for self-healing intentions. The desired variables used were the ratio of the shell/core, the type of surfactant (ionic and polymeric) and PMMA molecular weights. FTIR confirmed very fast crosslinking reaction between reactive epoxy and acrylate functional groups in AESO and thiol groups in TMPMP, which is very important for self-healing purposes. Furthermore, FTIR and thermal characterization results confirmed the encapsulation of both the resin and the curing agent components in two different core–shell microcapsules. The surface morphology of microcapsules obtained changed from dimpled and holed to plain for AESO and TMPMP respectively suggesting that it depends strongly on the nature of the core, type of surfactant and the ratio of shell/core. The produced core–shell microcapsules had a mean diameter of 7.9–169.7 µm and 9.9–64.1 µm for AESO/PMMA and TMPMP/PMMA, respectively. With changing the percentage of shell revealed that increasing the PMMA dosage in both surfactants causes a decrease in the size of TMPMP-filled microcapsules.

Biomimetic fabrication of melanin-like polydopamine nanofilm coating for structural colorization of textile

Structural colors originating from melanin in nature have attracted great attention in recent years. Structural colorization is an eco-friendly dyeing method which may be a substitute of the traditional highly polluting dyeing method. In this study, the structural color originating from biomimetic melanin-like polydopamine (PDA) nanofilm coating on flexible silk fabric and its color performance have been studied. Five different bright structural colors were obtained through the different polymerization reaction time of PDA nanofilm coating. However, the prepared structural colors nanofilm coating exist cracking and poor colorfastness due to the capillary tension during the formation of PDA film and the weak interaction with fabric substrate. P(GMA-co-PEGMA) copolymer containing reactive epoxy groups was used to improve the interface bonding strength between PDA film and substrate by forming covalent bond. The introducing covalent bond will be beneficial for the improving interface bonding strength, thus to obtain high colorfastness structural color coating. This research would provide experimental basis for the fabrication of crack-free and high colorfastness structural color coating originating from biomimetic melanin-like PDA nanofilm which would achieve the application in textile colorization.

Bifunctional polymer brush-grafted coronary stent for anticoagulation and endothelialization

At present, cardiovascular stent intervention faces clinical complications such as delayed endothelialization, late thrombosis and restenosis after implantation. In this work, a kind of bifunctional polymer brush-grafted coronary stent with anticoagulant and endothelial functions was developed. First, a block copolymer brush with zwitterionic structure consisting of sulfoethyl methacrylate (SBMA) and glycidyl methacrylate (GMA) was surface-induced grafted onto the surface of bare metal coronary stent by atom transfer radical polymerization. The diethylenetriamine NONOate (DETA NONOate), acted as nitric oxide (NO) donor to promote endothelialization, was then attached to polyglycidyl methacrylate (PGMA) brush by a reactive epoxy group to produce NO. The process of chemical modification and the release behavior of NO were characterized in detail. Moreover, the results of anticoagulant test, cytotoxicity test, endothelial cells (ECs) proliferation test and animal experiment of this bifunctional polymer brush-grafted coronary stent we proposed indicate that the zwitterion modified and NO supplied bifunctional coatings has good anticoagulant property, no cytotoxicity and significant endothelialization effect. This work opens the door to combine biological activity of NO and anticoagulant effect of zwitterions, which has great potential to address post-operative side effects associated with restenosis and late stent thrombosis.

Spatially-Regulated Deposition of Quantum Dots on the Patterned Polymer Brush

We have demonstrated direct patterning of surface initiator layer (SIL) for Atom Transfer Radical Polymerization (ATRP) using a sol-gel based "ink" containing (p-chloromethyl)phenyltrimethoxysilane and tetraethoxysilane for an inkjet printer. Mechanically/chemically robust and smooth micropatterns of SIL several tens of micrometer in width and 15 nm thickness were directly printed on silicon substrates under mild conditions (open to the atmosphere, at ~28 °C under >60% relative humidity). Subsequent surface-initiated ATRP of glycidyl methacrylate (GMA) under the air atmosphere gave area-selective/stepwise growth of homogeneous polyGMA brushes (pGMA) from the micropatterns of SIL. This area-selective growth of pGMA was also confirmed by a fluorescence microscopy. Because of chemical reactivity of epoxy groups on the grafted pGMA surfaces toward amino-functionalized nanomaterials, CdS/ZnS-alloyed quantum dots were spatially deposited only on the pGMA-covered regions with a complete area-selectivity.

A Lysine-Modified Polyethersulfone (PES) Membrane for the Recovery of Lanthanides.

Rare-earth elements (which include all lanthanides, scandium, and yttrium) play a key role in many fields including oil refining, metallurgy, electronics manufacturing, and other high-technology applications. Although the available lanthanide resources are enough for current levels of manufacturing, increased future demand for lanthanides will require new, efficient recovery methods to provide a sustainable supply. Membrane adsorbers are promising separation materials to recover lanthanides from high volumes of wastewater due to their tailorable surface chemistry, high binding capacity and high throughput. In this work, membrane adsorbers were synthesized by first using ultraviolet-initiated free radical polymerization to graft a poly(glycidyl methacrylate) (p-GMA) layer to the surface of polyethersulfone membranes. Then, the reactive epoxy groups of the grafted p-GMA were used for the covalent attachment of lysine molecules via a zinc perchlorate-catalyzed, epoxide ring-opening reaction at 35°C. Changes in membrane surface chemistry throughout the functionalization process were monitored with Fourier Transform Infrared Spectroscopy. The degree of grafting for the p-GMA film was quantified gravimetrically and increased with increasing polymerization time. Equilibrium adsorption experiments were performed for single specie solutions of La3+, Ce3+, Nd3+, Na+, Ca2+, and Mg2+ at pH 5.25 ± 0.25. Lysine-modified membranes showed negligible uptake of Na+, Ca2+, and Mg2+. The maximum capacities modeled by the Langmuir isotherm for La3+ and Ce3+ were 6.11 ± 0.58 and 6.45 ± 1.29 mg/g adsorbent, respectively. Nd3+ adsorbed to the membrane; however, the fit of the Langmuir model was not significant and it adsorbed to a lower extent than La3+ and Ce3+. Lower adsorption of the higher charge density species indicates that the primary binding mode is through the amine moieties of lysine and not the carboxylic acid. Dynamic adsorption experiments were conducted with 1 ppm La3+ feed solutions at different flow rates using either a single membrane or three membranes in series. The dynamic binding capacity at 50% breakthrough was independent of flowrate within the tested range. The low-temperature membrane functionalization methodology presented in this work can be used to immobilize biomolecules with even higher specificity, like engineered peptides or proteins, on membrane surfaces.

Modification of carbon black pigment: Cotton fabric colouring and anti‐bacterial finishing

AbstractFunctional polymer modified carbon black (CB) pigment (P‐(DMC‐co‐CHPMA)‐g‐MPTS/CB) with reactive epoxy and quaternary ammonium groups was designed and prepared via a thiol‐ene click chemistry reaction, and its dispersion ability in the aqueous phase, as well as its colouring and anti‐bacterial properties for cotton fabrics, were investigated. In considering both dispersion ability and reactive ability to cotton fabric, the mole ratio of the monomers (methacrylatoethyl trimethyl ammonium chloride [DMC] and 3‐chloro‐2‐hydroxypropyl methacrylate [CHPMA]) was discussed. Morphology and chemical properties of P‐(DMC‐co‐CHPMA)‐g‐MPTS/CB were tested by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X‐ray photoelectron spectroscopy, resulting in a weight content of copolymer (DMC‐co‐CHPMA) in P‐(DMC‐co‐CHPMA)‐g‐MPTS/CB of ca. 18%. P‐(DMC‐co‐CHPMA)‐g‐MPTS/CB was fixed onto cotton fabric via a nucleophilic‐substituted reaction between reactive epoxy groups on the CB surface and the hydroxyl groups of cotton fabric, which endowed good fastness to cotton fabric without either a fixing or an adhesive agent. Also, coloured cotton fabric demonstrated excellent anti‐bacterial activity towards Staphylococcus aureus and Escherichia coli O157:H7.

Aqueous Processed Biopolymer Interfaces for Single-Cell Microarrays

Single-cell microarrays are emerging tools to unravel intrinsic diversity within complex cell populations, opening up new approaches for the in-depth understanding of highly relevant diseases. However, most of the current methods for their fabrication are based on cumbersome patterning approaches, employing organic solvents and/or expensive materials. Here, we demonstrate an unprecedented green-chemistry strategy to produce single-cell capture biochips onto glass surfaces by all-aqueous inkjet printing. At first, a chitosan film is easily inkjet printed and immobilized onto hydroxyl-rich glass surfaces by electrostatic immobilization. In turn, poly(ethylene glycol) diglycidyl ether is grafted on the chitosan film to expose reactive epoxy groups and induce antifouling properties. Subsequently, microscale collagen spots are printed onto the above surface to define the attachment area for single adherent human cancer cells harvesting with high yield. The reported inkjet printing approach enables one to modulate the collagen area available for cell attachment in order to control the number of captured cells per spot, from single-cells up to double- and multiple-cell arrays. Proof-of-principle of the approach includes pharmacological treatment of single-cells by the model drug doxorubicin. The herein presented strategy for single-cell array fabrication can constitute a first step toward an innovative and environmentally friendly generation of aqueous-based inkjet-printed cellular devices.

Simple and feasible strategy to fabricate microcellular poly(butylene succinate) foams by chain extension and isothermal crystallization induction

ABSTRACTIn this article, a facile and efficient isothermal crystallization induction method was proposed to fabricate microcellular poly(butylene succinate) (PBS) foams with supercritical CO2. The good regularity of PE chain segments and high reactive epoxy groups in ethylene‐glycidyl methacrylate copolymer (PE‐g‐GMA) serving as a chain extender were employed to improve the crystallization behaviors, viscoelasticity, and foaming behaviors of PBS through chain extension reaction. The effect of PE‐g‐GMA content on the thermal properties, rheological performances, and cellular morphology of various PBS samples was investigated systematically. When the PE‐g‐GMA content switched from 7.5 to 10 wt %, an interesting transition from fine cells to microcells was observed in PBS/PE‐g‐GMA foams. Microcellular PBS foam modified by 10 wt % PE‐g‐GMA was successfully prepared at the foaming temperature of 87 °C and the induction time of 7 min, in which its cell size and cell density could reach 6.63 ± 1.93 μm and 3.75 × 109 cells cm−3, respectively. The formation of abundant but tiny spherocrystals in chain extended PBS samples made a considerable contribution for preparing microcellular PBS foams. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48850.

Hydrophilic spacer-arm containing magnetic nanoparticles for immobilization of proteinase K: Employment for speciation of proteins for mass spectrometry-based analysis

Proteinase K (ProK) is used for the degradation of proteins in cell lysates to isolate nucleic acids, and for the speciation of proteins for mass spectrometry analysis. In this work, a novel and sensitive immobilization process was developed for examination of protein mixtures by combining MALDI-ToF-MS and nLC-TIMS-ToF-MS/MS systems. To achieve these goals, magnetic nanoparticles (MPs) were prepared via thermal coprecipitation reaction under alkaline condition. The MPs were grafted with a silica layer (i.e., 3-(2,3-epoxypropoxy) propyltrimethoxysilane; EPTES) containing reactive epoxy groups. Then, the silica-grafted magnetic particles were coated with a long chain hydrophilic poly(ethylene glycol) diamine polymer (PEGDAP). The prepared materials were characterized by the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), scanning electron microscopy (SEM) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The VSM data show that the MPs@EPTES@PEGDAP has paramagnetic performance with a saturation magnetization of approximately 32.3 emu g−1. Proteinase K (EC 3.4.21.64) was covalently immobilized on the MPs@EPTES by reaction of its epoxy groups with amine groups of the enzyme. On the other hand, the ProK was immobilized on the MPs@EPTES@PEGDAP after activation with glutaraldehyde and the immobilization reaction was realized by the coupling reaction between aldehyde groups of the support and amine groups of the enzyme. The amounts of immobilized ProK on the MPs@EPTES and MPs@EPTES@PEGDAP were found to be 27.4 and 19.6 mg g−1and the retained activities were determined to be 29 and 87%, respectively. For the first time, some important features such as thermal and storage stabilities, reusability and potential use in protein speciation for mass spectrometry-based techniques were also evaluated. For examples, after six weeks of storage at 4 °C, the immobilized ProK on the MPs@EPTES@PEGDAP-ProK still maintained 59% of its initial activity. However, at the end of the six-week storage period, its free counterpart had lost all of its initial activity. The immobilized ProK was also utilized for degradation and identification of model proteins (i.e., α-2-HS glycoprotein, β-casein, bovine serum albumin and immunoglobulin). After enzymatic treatment, the digested peptides were analyzed and mapped by using nLC-TIMS-ToF-MS/MS systems.

Enhancement of flame‐retardant and mechanical performance of phenolic foam with the incorporation of cardanol‐based siloxane

ABSTRACTA novel cardanol‐based siloxane (SAECD), which has silicon groups and reactive epoxy groups, was synthesized. Its structure was confirmed by Fourier transform infrared spectrometry and 1H nuclear magnetic resonance. Then, phenolic foams (PFs) modified with different contents of SAECD were prepared. While addition of appropriate amount of SAECD into resin matrix enhances the flexural strength of PFs, incorporation of SAECD into PFs leads to a reduced pulverization ratio. The limiting oxygen index (LOI) increases continuously with the increasing addition of SAECD into PFs. The results of the cone calorimeter test showed that the addition of 3% SAECD could effectively reduce the heat release rate and total heat release of the foam by the condensed phase flame retardant mechanism. The TTI of the modified foam was delayed by 19 s; the PHRR, mean HRR, and THR of the modified foams decreased by 9.10%, 4.11%, and 7.55%, respectively, compared with those of the pristine PF. In addition to the increase in the toughness of the PF, SAECD addition can also improve the flame retardant properties of the PF.

A novel reversed-phase and weak anion-exchange mixed-mode stationary phase based on horizontal polar-copolymerized approach for separation of small organic molecules and inorganic anions

A novel silica-based reversed-phase/weak anion-exchange mixed-mode chromatography (MMC) stationary phase referred to as OTAS was synthesized based on the horizontal polar-copolymerized approach using trichlorooctadecylsilane (ODS) and (3-glycidyloxypropyl)trimethoxysilane (GPS) as ligands, and then followed by the reaction of epoxy group with diethylamine to introduce the tertiary ammonium functional group. The new stationary phase was characterized by instrumental analysis, and evaluated by separating the mixture of alkylbenzene homologues in reversed-phase mode and acidic organic compounds in ion-exchange chromatography mode, respectively. The results indicate that not only the baseline separation of 11 kinds of neutral and acidic organic compounds can be achieved successfully, but also 5 kinds of inorganic anions can be separated completely. The chromatographic property of OTAS column can be controlled by adjusting the molar ratio of ODS to GPS. Moreover, the OTAS column was used successfully to analyze the inorganic anions in the actual water samples. The good separation and selectivity of OTAS column suggests that the new MMC stationary phase can be used for the analysis of complex samples containing of neutral and acidic organic compounds or inorganic anions.

Metal-chelated cryogels for amyloglucosidase adsorption: application for continuous starch hydrolysis

In the present work, a new metal-chelating platform was designed by using IDA as a chelating agent and Cu(II) as an affinity component for amyloglucosidase adsorption. Poly(AAm-GMA) cryogels were used as structural elements, while GMA monomer served reactive epoxy groups for IDA immobilization. Synthesized cryogels were characterized by FTIR, SEM and EDX studies. Pore diameter of the whole polymeric structure was 3–10 \(\upmu \hbox {m}\). Effects of medium pH, temperature, ionic strength along with amyloglucosidase concentration were also investigated for more effective amyloglucosidase adsorption and maximum adsorbed amount of amyloglucosidase was \(2.93\,\hbox {mg }\hbox {g}^{-1}\) cryogel by the optimum conditions. Reusability profile of the poly(AAm-GMA)-IDA-\(\hbox {Cu}^{2+}\) cryogels was also studied and it was found that the synthesized cryogels could be used repeatedly for many times without any significant decrease on their adsorption capacity. Also continuous hydrolysis of starch by using immobilized form of amyloglucosidase in a column system was studied.

Sodium Hydroxide-Free Soy Protein Isolate-Based Films Crosslinked by Pentaerythritol Glycidyl Ether.

The soy protein isolate (SPI), sodium dodecylbenzenesulfonate (SDBS) and pentaerythritol glycidyl ether (PEGE) were used to make biodegradable films in this study. Unlike the usual method that adding sodium hydroxide (NaOH) during the SPI-based film casting, SDBS was used as a surfactant playing the similar role as NaOH. Since NaOH is a chemical with corrosiveness and toxicity, the replacing of NaOH by SDBS might reduce the hazard threat during the utilization of SPI-based films in food packing application. Furthermore, the presentation of SDBS helped dispersing the hydrophobic PEGE into the hydrophilic SPI. PEGE is a crosslinking agent with multiple reactive epoxy groups. The chemical structures and micro morphologies of the fabricated films were investigated by means of FTIR, XRD, and SEM. The thermal stabilities of the films were examined by means of the thermo-gravimetric analysis. After the chemical crosslinking, the ultimate tensile strength of the film was significantly increased, meanwhile, the water absorption was dramatically decreased. It was concluded that the SPI-based film containing 4% PEGE achieved the optimal performance.

Methylpiperidine-functionalized graphene oxide for efficient curing acceleration and gas barrier of polymer nanocomposites

We synthesized methylpiperidine-functionalized graphene oxide (MP-GO) by introducing 4-amino-1-methylpiperidine into reactive epoxy and/or carboxylic acid groups on pristine GO. Then, we applied the MP-GO as a curing catalyst for polyimide (PI) nanocomposites. The MP-GO was found to be an effective base-catalysts for the thermal conversion of polyamic acid (PAA) precursor to PI. Interestingly, when 3 wt% of MP-GO was added to the PI matrix, the complete imidization of nanocomposites was achieved at a temperature lower than 200 °C. In addition, the PI/MP-GO nanocomposite films exhibited reinforcement of the oxygen barrier properties which were even better than those of pristine PI, due to the excellent dispersion state of MP-GO and the favorable non-covalent interaction between MP-GO and the PI matrix. Comparison to pristine PI, the oxygen permeability of nanocomposite films that contained only 1 wt% of MP-GO loading was significantly decreased, by about 80%. Furthermore, all the PI/MP-GO nanocomposites exhibited high thermal stability.

Construction compositions based on integrated binding of thermoplastic waste

The paper suggests a solution of the actual problem of processing polymeric municipal waste in building materials with a high complex of decorative and operational properties. The work is aimed at studying the processes of structure formation and hardening in the system “multicomponent thermoplastic binder - mineral filler” in the manufacture of polymer concrete products for construction purposes. During the research methods of infrared spectroscopy, differential thermal analysis, standard methods for determining the structure and properties of building products were used. As a result of the research, compositions of a complex thermoplastic binder including polymeric consumption waste (PET, PP) are proposed taking into account the volumes of their sampling at the waste sorting stations. An additive - a compatibilizer based on an ethylene-vinyl acetate copolymer with grafted reactive polar acrylate and epoxy groups, is also included. It was found that the introduction of a compatibilizer promotes the activation of the physicochemical interaction between the components of the polymer binder and between the polymer matrix and the mineral surface of the fillers. There was also an increase in the density and strength of the resulting artificial stone. The optimal content of the additive in an amount of 5% of the total mass of the complex binder was experimentally determined. With the introduction of a compatibilizer in smaller amounts, the effect of strengthening the flexural strength decreases, and when more compatibilizers are introduced, the strength of the products remains the same at bending, and the compressive strength decreases. Mechanisms of interphase interactions are proposed, taking into account the chemical-mineralogical composition of mineral fillers (based on carbonates and aluminosilicates). The possibility of participation of epoxide and acrylate functional groups in the formation of intramolecular and intermolecular hydrogen bonds with the formation of polyassociates was established. The revealed patterns of interaction make it possible to ensure the compatibility of weakly polar PET with other multitonnage thermoplastics, as well as compatibility of the complex polymer binder with mineral fillers. The management of the processes of structure formation in the studied systems makes it possible to obtain high decorative and operational parameters of the construction products.

Electrospun epoxy-based nanofibrous membrane containing biocompatible feather polypeptide for highly stable and active covalent immobilization of lipase.

In this study, a novel poly (glycidyl methacrylate-co-methylacrylate)/feather polypeptide (P(GMA-co-MA)/FP) nanofibrous membrane containing reactive epoxy groups and biocompatible feather polypeptide (FP) was fabricated by electrospinning which was the first time used for the covalent immobilization of lipase. The results of FTIR spectra and SEM images of nanofibrous membrane before and after immobilization demonstrated that lipase has been successfully covalently immobilized on the nanofibrous membrane. FP was beneficial for the stabilization of the enzyme conformation which would promote the improvement of enzyme activity and stability. The P(GMA-co-MA)/FP-Lipase possesses a wide pH tolerance and high thermal stability, good reuse and organic solvent stability. The residual relative activity of immobilized lipase was about 38% which was treated under 70 °C for 3 h. The residual relative activity of immobilized lipase was 62% after 7 reuses and nearly 75% after being treated in methanol for 12 h. This study revealed that the biocompatible FP could be used as an additive to improve the enzyme activity and stability of immobilized enzyme on nanofibrous membranes.

Interaction between carbon fibers and polymer sizing: Influence of fiber surface chemistry and sizing reactivity

Different aspects of the interaction of carbon fibers and epoxy-based polymer sizings are investigated, e.g. the wetting behavior, the strength of adhesion between fiber and sizing, and the thermal stability of the sizing layer. The influence of carbon fiber surface chemistry and sizing reactivity is investigated using fibers of different degree of anodic oxidation and sizings with different number of reactive epoxy groups per molecule. Wetting of the carbon fibers by the sizing dispersion is found to be specified by both, the degree of fiber activation and the sizing reactivity. In contrast, adhesion strength between fibers and sizing is dominated by the surface chemistry of the carbon fibers. Here, the number of surface oxygen groups seems to be the limiting factor. We also find that the sizing and the additional functionalities induced by anodic oxidation are removed by thermal treatment at 600 °C, leaving the carbon fiber in its original state after carbonization.

Electrospun nanofibrous membranes containing epoxy groups and hydrophilic polyethylene oxide chain for highly active and stable covalent immobilization of lipase

Immobilization of enzymes on nanofibrous membranes could offer easy recycling and feasible continuous operations. In this study, a novel terpolymer poly (glycidyl methacrylate-co-methylacrylate)-g-polyethylene oxide (P(GMA-co-MA)-g-PEO) containing reactive epoxy groups and hydrophilic polyethylene oxide branch chain was synthesized. Electrospun P(GMA-co-MA)-g-PEO nanofibrous membrane was used for the immobilization of lipase molecules by covalent binding with the epoxy groups. The influences of the enzyme loading and activity by nanofibrous membranes with different content of monomers and immobilization temperature were investigated. The immobilized lipase achieved high enzyme loading of 150 mg/g and the maximum activity of 0.673 U/mg under the optimum immobilization conditions. The hydrophilic PEO branch chain was beneficial for the stabilization of the enzyme conformation which would promote the improvement of enzyme activity and stability. The results of FTIR spectra and SEM images of nanofibrous membranes before and after immobilization demonstrated that lipase has been successfully covalently immobilized on the nanofibrous membranes. The optimal pH and temperature were 7.0 and 35 °C for catalysis reaction of the immobilized lipase. The stabilities of the immobilized lipase were also investigated. The results demonstrated that the immobilized lipase has good thermal stability, reusability and organic solvent stability. The good stabilities of immobilized lipase revealed that P(GMA-co-MA)-g-PEO nanofibrous membrane is an excellent carrier for enzyme immobilization.