Palladium and carbon synergistically catalyzed room-temperature hydrodeoxygenation(HDO) of vanillyl alcohol–A typical lignin model molecule

Vanillyl alcohol,which is made up of an aromatic ring,an alcoholic hydroxyl group,a phenolic hydroxyl group and a methoxy group,was selected as the model molecule of lignin.Various carbon materials supported Pd catalysts were chosen to catalyze the HDO of vanillyl alcohol.The catalysts were characterized via TEM,TPD,XRD,XPS and CO-chemisorption.It was found that different carbon materials could obviously influence the particle sizes,dispersion and distribution of Pd or Pd O particles.Palladium and carbon can synergistically catalyze the room-temperature HDO of vanillyl alcohol even at room temperature,and the carboxyl group was found to be the effective active acid site during the reaction.Possible reaction mechanism was also proposed.The existence of the effective active acid sites on the carbon supports could obviously lower the reaction temperature without decreasing the selectivity,as a result,making the production of renewable fuels by HDO much more economically feasible,which is of much importance.     

Preparation and characterization of biotinylated and enzyme‐immobilized heterobifunctional latex particles as nanobio devices

A novel biotinylated and enzyme‐immobilized nanobio device was prepared with heterobifunctional composite latex particles. Hemispherical poly(glycidyl methacrylate‐co‐divinylbenzene)/polystyrene [P(GMA‐DVB)/PSt] particles with epoxy and hydroxyl groups were prepared by soap‐free seeded emulsion polymerization with P(GMA‐DVB) seed particles. Hydroxyl groups were introduced to PSt chain terminals in the seeded stage by adding 2‐mercaptoethanol as a chain‐transfer agent. To obtain the desired hemispherical structure particles, we studied the effects of the preswelling process, the type and amount of solvents added in the seeded polymerization step, the weight ratio of the secondary monomer (styrene) to the seed particle (M/P), and the type of initiators. Under suitable conditions, heterobifunctional P(GMA‐DVB)/PSt was obtained, which was confirmed by observing the binding of streptavidin–colloidal gold with transmission electron microscopy (TEM). To obtain biotinylated and enzyme‐immobilized particles, 5‐(N‐succinimidyloxycarbonyl)pentyl D‐biotinamide was first reacted with the hydroxyl group on the PSt domain of the particle. Pyruvate kinase (PK) was then directly immobilized to the biotinylated particles through a reaction with the epoxy group in the PGMA domain. The monolayer of PK on the latex particle surface was considered to be formed by covalent binding. The activity of immobilized PK was almost conserved, even after being stored at 4 °C for 48 days. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 562–574, 2005     

Surface functionalization of multi‐walled carbon nanotubes through surface‐initiated atom transfer radical polymerization of glycidyl methacrylate

Herein, we report the fabrication of glycidyl methacrylate (GMA) polymeric conjugates of shortened multi‐walled carbon nanotubes (sMWCNT). The synthesis method involves the attachment of initiator on the surface of nanotubes followed by surface initiated atom transfer radical polymerization (SI‐ATRP) of GMA from the initiator‐bound sMWCNT surface. This is achieved by the procedure consisting of three important steps: introduction of amino groups onto the sMWCNT and attachment of polymerization initiator, 2‐bromo‐2‐methylpropinonyl bromide, and polymerization of GMA. The structure and properties of the resultant polymeric conjugates were characterized by Fourier transform infrared (FT‐IR) spectroscopy, Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) and SEM. The FT‐IR analysis of polymeric conjugates shows infrared (IR) peaks characteristic of GMA. AFM, TEM and SEM images clearly show the formation of poly(glycidyl methacrylate)(PGMA) polymer on sMWCNT surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of reactive phosphonated methacrylates

Five novel phosphonated mono‐ and dimethacrylate monomers have been synthesized by two different routes. Monomers 1 and 2 were synthesized by reactions of methacryloyl chloride with diethyl (2‐hydroxyphenyl) phosphonate or tetraethyl (2,5‐dihydroxy‐1,4‐phenylene) bisphosphonate; monomers 3 and 4 by reactions of α‐(chloromethyl)acryloyl chloride (CMAC) first with dimethyl (2‐hydroxyethyl) phosphonate and then with benzoic or formic acids. The reaction of CMAC with two moles of dimethyl (2‐hydroxyethyl) phosphonate gave monomer 5 . Thermal homopolymerization of monomers 1 , 3 , 4 , and 5 and copolymerization of monomer 1 with methyl methacrylate (MMA) were investigated using azobisisobutyronitrile (AIBN) at 60 °C. Glass transition temperatures were observed for poly‐ 1 , poly(MMA‐co‐ 1 ) (50:50), poly(MMA‐co‐ 1 ) (90:10), PMMA, poly‐ 3 , and poly‐ 5 at 52, 90, 99, 129, 50, and 70 °C, respectively. TGA analysis of these polymers indicated formation of char on combustion. Homo‐ and/or copolymerization behavior of the synthesized monomers with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy propyloxy) phenyl] propane (Bis‐GMA) were investigated with photodifferential scanning calorimetry. The maximum rate of polymerizations decreased in the following order: Bis‐GMA～ 3 > 1 > 4 > 5 . The conversions of monomers 1 , 3 , 4 , and 5 (73.9, 85.9, 98.2, and 62.2%) were very high compared with Bis‐GMA (40.5%). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5737–5746, 2009     

A successive route to amphiphilic graft copolymers with a hydrophilic poly(3‐hydroxypropyl methacrylate) backbone and hydrophobic polystyrene side chains

A successive method for preparing novel amphiphilic graft copolymers with a hydrophilic backbone and hydrophobic side chains was developed. An anionic copolymerization of two bifunctional monomers, namely, allyl methacrylate (AMA) and a small amount of glycidyl methacrylate (GMA), was carried out in tetrahydrofuran (THF) with 1,1‐diphenylhexyllithium (DPHL) as the initiator in the presence of LiCl ([LiCl]/[DPHL]₀ = 2), at −50 °C. The copolymer poly(AMA‐co‐GMA) thus obtained possessed a controlled molecular weight and a narrow molecular weight distribution (M_w /M_n = 1.08–1.17). Without termination and polymer separation, a coupling reaction between the epoxy groups of this copolymer and anionic living polystyrene [poly(St)] at −40 °C generated a graft copolymer with a poly(AMA‐co‐GMA) backbone and poly(St) side chains. This graft copolymer was free of its precursors, and its molecular weight as well as its composition could be well controlled. To the completed coupling reaction solution, a THF solution of 9‐borabicyclo[3.3.1]nonane was added, and this was followed by the addition of sodium hydroxide and hydrogen peroxide. This hydroboration changed the AMA units of the backbone to 3‐hydroxypropyl methacrylate, and an amphiphilic graft copolymer with a hydrophilic poly(3‐hydroxypropyl methacrylate) backbone and hydrophobic poly(St) side chains was obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1195–1202, 2000     

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)₃] successfully yielded linear polyesters having hydroxyl functionality (M_n = ca. 1.0 × 10⁴). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009     

FDCA基聚酯的合成、性能及应用研究进展

生物质资源是一种储量丰富的可再生资源。生物质资源的高效利用不仅具有非常巨大的经济和生态价值,而且对新能源与生物基合成材料的可持续发展战略具有重大意义。由植物纤维素等生物质材料经生物或者简单化学过程处理,可获得丰富的生物基单体2,5-呋喃二甲酸(FDCA)。FDCA可用于生物基聚酯材料的合成。FDCA系列聚酯材料性能优异,可作为由石油基单体对苯二甲酸(PTA)而合成的芳香族聚酯材料(例如PET)的一种潜在的高性能生物可降解替代材料。本文简要说明了生物基单体FDCA的物性及制备方法,并重点阐述了包括聚呋喃二甲酸乙二酯(PEF)与聚呋喃二甲酸丁二酯(PBF)等一系列FDCA基聚酯材料的合成及性质,同时对FDCA基聚酯材料的应用进展进行了简要介绍,最后对FDCA基聚酯生物基合成材料的发展前景作了初步展望。     

Hydroxyl Functionalized Uniform‐Porous Beads,Synthesis and Chromatographic Use

Uniform‐porous poly(dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate), poly(DHPM‐co‐EDM) particles were synthesized as an alternative packing material for reversed phase chromatography. In the synthesis, poly(glycidyl methacrylate‐ethylene dimethacrylate), poly(GMA‐co‐EDM) particles were obtained by a multi‐stage swelling and polymerization protocol, the so called “modified seeded polymerization”. For this purpose, 2.4 µm polystyrene seed particles were first swollen by dibutyl phthalate (DBP) and then by a monomer mixture including glycidyl methacrylate and ethylene dimethacrylate. The repolymerization of monomer phase in the swollen seed particles provided porous uniform particles approximately 7 µm in size. Poly(DHPM‐co‐EDM) particles were obtained by the acid hydrolysis of the particles synthesized with different GMA feed concentrations. These particles were used as column‐packing material in the reversed phase separation of alkylbenzenes. The retention factor‐acetonitrile concentration diagrams clearly showed that the polarity of packing material could be controlled by changing the GMA feed concentration in the “modified seeded polymerization”. The packing materials with more hydrophobic character (i.e., poly(EDM) and poly(DHPM‐co‐EDM) particles produced with the GMA feed concentrations up to 20%) exhibited better chromatographic performance in the reversed phase mode.     

Studies of methyl methacrylate–glycidyl methacrylate copolymers: Copolymerization to low molecular weights and modification by ring-opening reaction of epoxy side groups

The copolymerization of methyl methacrylate (MMA) with glycidyl methacrylate (GMA) at 60°C with 2,2′-azobisisobutyronitrile (AIBN) as radical initiator and in the presence of thiophenol (TP) as chain-transfer agent has been investigated. Monomer reactivity ratios for MMA and GMA are found to be r₁ (MMA) = 0.80 ± 0.015 and r₂ (GMA) = 0.70 ± 0.015, from which Q and e values are calculated to be 0.68 and ?0.36 for GMA. The initial rate of copolymerization R_p at 60°C with AIBN (0.02 mole/l.) and TP (0.1, 0.01 mole/l.) were found to increase nonlinearly with increasing GMA concentration in the monomer feed. Homopolymerizations of MMA and GMA monomers were studied in the presence and in the absence of thiophenol. The values of δ (= k_t^1/2/k_p) for MMA and GMA were determined to be 10.25 and 3.00 (mole-sec/l.)^1/2, respectively. Using the values r₁ (MMA), r₂ (GMA), δ₁ (MMA), δ₂ (GMA), and R_p, the cross-termination constants ? for MMA–GMA monomers were determined (average value ? = 0.42). The increase in R_p values with increasing GMA content has been attributed to the cross-termination of MMA–GMA radicals. The transfer constant of TP has also been determined for GMA and found to be 1.00. A MMA–GMA copolymer of low molecular weight, containing 2.01% of oxirane oxygen, was modified by opening of the oxirane ring of GMA by reaction with diethanolamine (DEA). The reaction was carried out at 70 ± 1°C, the copolymer content of epoxy groups and the amine being assumed to be in the molar ratio of 1:4. Addition of a hydrogen-bond acceptor like nitrobenzene decreases, while addition of a hydrogen-bond donor like phenol increases the rate of epoxy ring opening with DEA. This indicates that a hydrogen-bonded intermediate is involved in this reaction and that it weakens the epoxy ring and enhances the rate of its opening with DEA. From the studies of the conversion rates, existence of a “nonspecific” side reaction has been shown which involves the reaction of the terminal epoxy groups of the copolymer and the hydroxyl groups of DEA or formed in the reaction with DEA (involves a chain coupling). DEA can be trifunctional in this reaction. This has been further confirmed from the increase of number-average molecular weights M?_n of the copolymers resulting from this coupling and the nitrogen content in the copolymers after modification with DEA.     

Development of reactive methacrylates based on glycidyl methacrylate

Six methacrylate monomers have been synthesized for use as reactive diluents in dental composites and evaluated to investigate the relationship between molecular structure and monomer reactivity. Four were synthesized by reactions of glycidyl methacrylate (GMA) with various acids, 2‐(2‐methoxyethoxy)acetic acid ( 1 ), 2‐(2‐(2‐methoxyethoxy)ethoxy)acetic acid ( 2 ), cyanoacetic acid ( 3 ), and benzoic acid ( 4 ); others were synthesized by reactions of GMA with diethyl hydrogen phosphate ( 5 ) or methanol ( 6 ). Monomers 1 and 2 are novel, 3 seems to be novel, 4 and 6 were synthesized via a novel method, and the synthesis of 5 was described in the literature. The monomers showed high crosslinking tendencies during thermal bulk polymerizations. The photo‐, homo‐, and copolymerization behavior of the monomers with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy)phenyl]propane (Bis‐GMA) were investigated. The maximum rate of polymerizations of monomers 2 – 6 was found to be greater than triethyleneglycol dimethacrylate, Bis‐GMA, 2‐hydroxyethyl methacrylate, and glycerol dimethacrylate. For the more reactive monomers ( 2 , 3 , and 4 ), the oxygen sensitivity of polymerization was found to be low due to a hydrogen abstraction/chain transfer reaction. The computationally calculated dipole moment and lowest unoccupied molecular orbital energies indicated that there seems to be a correlation between these quantities and reactivity for ester linked monomers ( 1 – 5 ), which was also supported by ¹³C NMR data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3787–3796, 2010     

Temperature‐Directed Biocatalysis for the Sustainable Production of Aromatic Aldehydes or Alcohols

The biosynthesis of aromatic aldehydes and alcohols from renewable resources is currently receiving considerable attention because of an increase in demand, finite fossil resources, and growing environmental concerns. Here, a temperature‐directed whole‐cell catalyst was developed by using two novel enzymes from a thermophilic actinomycete. Ferulic acid, a model lignin derivative, was efficiently converted into vanillyl alcohol at a reaction temperature at 30 °C. However, when the temperature was increased to 50 °C, ferulic acid was mainly converted into vanillin with a productivity of 1.1 g L^?1 h^?1. This is due to the fact that the redundant endogenous alcohol dehydrogenases (ADHs) are not active at this temperature while the functional enzymes from the thermophilic strain remain active. As the biocatalyst could convert many other renewable cinnamic acid derivatives into their corresponding aromatic aldehydes/alcohols, this novel strategy may be extended to generate a vast array of valuable aldehydes or alcohols.     

Graft Polymerization of Vinyl Monomers Onto Carbon Black by Use of the Redox System Consisting of Ceric Ions and Carbon Black Carrying Alcoholic Hydroxyl Groups

The radical graft polymerization of vinyl monomers onto carbon black initiated by a redox system consisting of ceric ion and carbon black having alcoholic hydroxyl groups was investigated. The introduction of alcoholic hydroxyl groups onto the carbon black surface was achieved by the reaction of carbon black with alcoholic hydroxyl radicals, formed by the reaction of alcohol with benzoyl peroxide. The rate of the polymerization of acrylamide (AAm) initiated by the redox system was found to increase in the following order of hydroxyl groups: 1-hydroxyoctyl < 1-hydroxypropyl < 1-hydroxyethyl < hydroxymethyl < 1-hydroxy-1-methylethyl. In the redox polymerization, poly-AAm was effectively grafted onto carbon black by propagation of the polymer from the radical formed by the reaction of ceric ions with the alcoholic hydroxy groups. The percentage of grafting increased with increasing conversion. By use of this redox system, poly(acrylic acid), polyacrylonitrile, and poly(N-vinyl-2-pyrrolidone) could be grafted onto carbon black, but poly(methyl methacrylate) and polystyrene could not be so grafted. The graft polymerization of AAm by use of a redox system consisting of ceric ion and PVA-grafted carbon black was also investigated.     

Synthesis and characterization of novel poly(amide urea)s,materials with outstanding mechanical properties

Four novel A‐B condensation monomers containing an amine and a carboxylic acid function are described, along with their polymerization to give main chain aromatic poly(amide urea)s. The monomers, and the polymer structural unit, are N,N′‐diphenylurea derivatives. When comparing wholly aromatic polyamides, or aramids, with the poly(amide urea)s described herein, we find that the chemical resistance to hydrolysis of the later polymers increases and their thermal resistance is diminished due to the main chain urea groups, whereas their water uptake is not greatly modified. The most striking result of the new poly(amide urea)s is their outstanding mechanical resistance: their Young's modulus rises as high as 5.5 GPa and their tensile strengths as high as 170 MPa for unoriented films prepared at laboratory scale by casting. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5398–5407, 2007     

生物基超韧聚乳酸复合材料的制备与性能

采用来源于可再生资源的聚醚酰胺弹性体（PEBA）增韧聚乳酸（PLA）制备超韧聚乳酸（PLA/PEBA-GMA）复合材料.为了提高PEBA与PLA之间的相容性,选择极性单体甲基丙烯酸缩水甘油酯（GMA）、共接枝单体乙烯基吡咯烷酮（NVP）及引发剂过氧化二异丙苯（DCP）对PEBA进行接枝改性制备PEBA-GMA.研究了接枝单体组分的用量（m/g）对PLA/PEBA-GMA复合材料性能的影响.研究发现,随着接枝单体组分用量的提高,复合材料的缺口冲击强度逐渐增大,当接枝单体组分GMA,NVP和DCP的用量分别为2.5,2.5和0.25 g时,复合材料的冲击强度高达88.6 kJ/m²,断裂伸长率为164.1%.研究表明,在熔融共混过程中,聚乳酸的端基（—OH和—COOH）与PEBA-GMA上环氧基团发生反应,有效改善两相间的界面相容性,随着接枝单体组分比例的提高,分散相PEBA-GMA的粒子尺寸逐渐减小且分布均匀.     

Hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s: Synthesis,characterization, end‐group modification,and optical properties

Novel AB₂‐type monomers such as 3,5‐bis(4‐methylolphenoxy)benzoic acid ( monomer 1 ), methyl 3,5‐bis(4‐methylolphenoxy) benzoate ( monomer 2 ), and 3,5‐bis(4‐methylolphenoxy)benzoyl chloride ( monomer 3 ) were synthesized. Solution polymerization and melt self‐polycondensation of these monomers yielded hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s. The structure of these polymers was established using FTIR and ¹H NMR spectroscopy. The molecular weights (M_w) of the polymers were found to vary from 2.0 × 10³ to 1.49 × 10⁴ depending on the polymerization techniques and the experimental conditions used. Suitable model compounds that mimic exactly the dendritic, linear, and terminal units present in the hyperbranched polymer were synthesized for the calculation of degree of branching (DB) and the values ranged from 52 to 93%. The thermal stability of the polymers was evaluated by thermogravimetric analysis, which showed no virtual weight loss up to 200 °C. The inherent viscosities of the polymers in DMF ranged from 0.010 to 0.120 dL/g. End‐group modification of the hyperbranched polymer was carried out with phenyl isocyanate, 4‐(decyloxy)benzoic acid and methyl red dye. The end‐capping groups were found to change the thermal properties of the polymers such as T_g. The optical properties of hyperbranched polymer and the dye‐capped hyperbranched polymer were investigated using ultraviolet‐absorption and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5414–5430, 2008     

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35 %, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC⁴D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of <15 % (averaged for several metal ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.     

One-step functionalization of multi-walled carbon nanotubes by radiation-induced graft polymerization and their application as enzyme-free biosensors

This paper describes the functionalization of multi-walled carbon nanotubes (MWNTs) by radiation-induced graft polymerization (RIGP) of vinyl monomers with functional groups and the application of these MWNTs in enzyme-free biosensors. The vinyl monomers used were acrylic acid (AAc), methacrylic acid (MAc), glycidyl methacrylate (GMA), maleic anhydride (MAn), and 4-vinylphenylboronic acid (VPBAc). Tubular-type MWNTs were obtained via RIGP of various vinyl monomers. The poly(VPBAc)-grafted MWNTs (PVBAc-g-MWNTs) were used as sensing sites in enzyme-free glucose sensors for the detection of glucose without enzymes. The PVBAc-g-MWNTs electrode displayed an excellent linear response to glucose concentration in the range 1.0–10 mM. The functionalized MWNTs prepared by RIGP can be used as biosensor materials.     

Copolymerization of N‐vinylcaprolactam and glycidyl methacrylate: Reactivity ratio and composition control

Free‐radical copolymerizations of N‐vinylcaprolactam (VCL) and glycidyl methacrylate (GMA) were investigated to synthesize temperature‐responsive reactive copolymers with minimized compositional heterogeneity. The average copolymer composition was determined by Fourier transform infrared and nuclear magnetic resonance techniques. The reactivity ratios for VCL and GMA were found to be 0.0365 ± 0.0009 and 6.44 ± 0.36 by the Fineman–Ross method and 0.039 ± 0.006 and 6.75 ± 0.29 by the Kelen–Tudos method, respectively. When prepared by batch polymerization, VCL–GMA copolymers had a highly heterogeneous composition and fractions of different solubilities in water. The use of a gradual feeding technique, which included the sequential addition of more reactive GMA monomer into the reaction, yielded copolymers with much more homogeneous composition. The produced copolymers with 0.9 and 0.11 fractional GMA contents preserved their temperature‐responsive properties and precipitated from aqueous solutions when the temperature exceeded 31 °C. The GMA units in the VCL–GMA copolymers were capable of reacting with amino end‐functionalized poly(ethylene oxide) at room temperature to produce poly(N‐vinylcaprolactam)–poly(ethylene oxide) graft copolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 183–191, 2006     

Casting of poly (vinyl alcohol)/glycidyl methacrylate reinforced with titanium dioxide nanoparticles for proton exchange fuel cells

Gamma irradiation was used for cross-linking poly (vinyl alcohol) (PVA) and glycidyl methacrylate (GMA) mixtures of different compositions. Specifically, 0.5 wt% titanium dioxide (TiO₂) nanoparticles were added and blended well with the casting mixture prior to exposure to the irradiation dose. Next, 10 kGy was found to be the optimum dose for achieving the desired physical and chemical properties of the membrane. Characterizations of the cast membranes were carried out by Fourier transformer infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and positron annihilation lifetime spectroscopy (PALS). The properties of the membrane were also characterized by ion exchange capacity (IEC), water uptake, and tensile strength and were assessed in relation to application in proton exchange membrane fuel cells (PEMFCs). A maximum proton conductivity of 7.3 × 10^?2 S cm^?1 was obtained for the membrane having 20 % GMA, 80 % PVA, and 0.5 % TiO₂, and its activity and durability in a membrane electrode assembly (MEA) were compared to those of a commercial Nafion® 1350.     

Conjugated vinyl derivatives of chitooligosaccharide: Synthesis and characterization

The introduction of a conjugated vinyl group to chitooligosaccharide (COS) has been easily accomplished by the coupling of glycidyl methacrylate (GMA) to COS in aqueous solution without an additional catalyst. Depolymerization of chitosan was carried out by deaminative cleavage using sodium nitrite. The average degree of polymerization of COS could be controlled by varying the molar ratio of sodium nitrite and the amino group of chitosan. The degree of substitution (percentage), as determined by ¹H NMR, of GMA to COS increased up to 60% at a reaction time of 48 h. The structure of products (COS‐GMAs) were identified by Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR. The resulting COS‐GMAs were readily soluble in neutral water, like the original COS, and exhibited an excellent antimicrobial activity. The reactivity of COS‐GMA was investigated by the reaction with poly(vinyl alcohol) (PVA). The reaction products were found to have a lower crystallinity than PVA because of the introduction of the COS‐GMA units. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 880–887, 2001