| 1. |
- Ajjan, Fátima, et al.
(författare)
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Innovative polyelectrolytes/poly(ionic liquid)s for energy and the environment
- 2017
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Ingår i: Polymer international. - : WILEY. - 0959-8103 .- 1097-0126. ; 66:8, s. 1119-1128
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Forskningsöversikt (refereegranskat)abstract
- This paper presents the work carried out within the European project RENAISSANCE-ITN, which was dedicated to the development of innovative polyelectrolytes for energy and environmental applications. Within the project different types of innovative polyelectrolytes were synthesized such as poly(ionic liquid)s coming from renewable or natural ions, thiazolium cations, catechol functionalities or from a new generation of cheap deep eutectic monomers. Further, macromolecular architectures such as new poly(ionic liquid) block copolymers and new (semi)conducting polymer/polyelectrolyte complexes were also developed. As the final goal, the application of these innovative polymers in energy and the environment was investigated. Important advances in energy storage technologies included the development of new carbonaceous materials, new lignin/conducting polymer biopolymer electrodes, new iongels and single-ion conducting polymer electrolytes for supercapacitors and batteries and new poly(ionic liquid) binders for batteries. On the other hand, the use of innovative polyelectrolytes in sustainable environmental technologies led to the development of new liquid and dry water, new materials for water cleaning technologies such as flocculants, oil absorbers, new recyclable organocatalyst platforms and new multifunctional polymer coatings with antifouling and antimicrobial properties. All in all this paper demonstrates the potential of poly(ionic liquid)s for high-value applications in energy and enviromental areas. (c) 2017 Society of Chemical Industry
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| 2. |
- Amanizadeh, Farhad, et al.
(författare)
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Starve fed emulsion copolymerization of vinyl acetate and 1-hexene at ambient pressure
- 2014
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 63:10, s. 1850-1855
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Tidskriftsartikel (refereegranskat)abstract
- A novel emulsion copolymer of vinyl acetate (VAc) and 1-hexene was synthesized at ambient pressure. The feeding technique, initiation system and reaction time of the copolymerization were optimized based on molecular characteristics such as the weight contribution of 1-hexene in the copolymer chains and glass transition temperature (T-g) as well as on bulk properties like minimum film-formation temperature (MFFT) and solid content. According to nuclear magnetic resonance spectroscopy and differential scanning calorimetry results, the combination of starve feeding and redox initiation, within a reaction time of 4h, effectively led to the copolymerization at ambient pressure between highly reactive polar VAc monomers and non-polar 1-hexene monomers of low reactivity. The copolymer showed a lower T-g and MFFT, and a reasonable solid content compared to the poly(vinyl acetate) (PVAc) homopolymer. The consumption rate, hydrolysis of acetate groups and chain transfer reactions during the polymerization were followed using infrared spectroscopy. Based on the results, the undesirable reactions between the VAc blocks were hindered by the neighbouring 1-hexene molecules. Tensile testing revealed an improvement in the toughness and elongation at break of VAc-1-hexene films compared to PVAc films.
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| 3. |
- Camacho, W., et al.
(författare)
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Near infrared (NIR) spectroscopy compared with thermogravimetric analysis as a tool for on-line prediction of water diffusion in polyamide 6,6
- 2002
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 51:12, s. 1366-1370
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Tidskriftsartikel (refereegranskat)abstract
- NIR spectroscopy in the transmission mode and thermogravimetric analysis were used to predict diffusion of water into polyamide 6,6 samples immersed in water at 40, 60, 75 and 90degreesC for different periods of time. The sorption curves between 40 and 75 were sigmoidal indicating that the surface concentration was time dependent. The sorption curves were readily fitted by the use of a time-dependent surface concentration and a water-concentration-dependent diffusivity. The zero-concentration water diffusivity decreased non-linearly and the activation energy of diffusion increased from 24 to 58 kJ mol(-1), with decreasing temperature. The surface concentration relaxation time decreased rapidly. The sorption of water in thick polyamide samples was readily characterized by FT-NIR spectroscopy. The accuracy and feasibility of this method was similar to conventional thermogravimetric methods. The greatest advantage of FT-NIR, however, is the possibility of detecting and monitoring the moisture concentration on-line and in a non-destructive way.
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| 4. |
- de Melo, J. Sergio Seixas, et al.
(författare)
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Fluorescence studies on the interaction between pyrene-labelled poly(acrylic acid) and cyclodextrins
- 2007
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Ingår i: Polymer International. - : Wiley. - 0959-8103 .- 1097-0126. ; 56:7, s. 882-899
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Tidskriftsartikel (refereegranskat)abstract
- The interactions, in aqueous media, between a pyrene-labelled polyelectrolyte poly(acrylic acid) (PAAMePy) with two different degrees of labelling and beta- and gamma-cyclodextrins (beta- and gamma-CD) were studied using absorption and fluorescence (steady-state and time-resolved) techniques. In addition to qualitative and quantitative parameters obtained from absorption and steady-state fluorescence spectra, time-resolved fluorescence data are presented, allowing additional important observations regarding the nature of the interactions. From the overall data it was possible to conclude that in the case of interaction with gamma-CD the efficient encapsulation of two pyrene units into the cavity of the cyclodextrin molecule leads to a decrease in the number of available free monomers and an increase in the number of preformed ground-state dimers (GSDs) of pyrene. It was also shown that contrary to the situation in water, where only intramolecular interactions are present, the addition of gamma-CD leads to new interpolymeric interactions. The absence of significant changes is noted when the interactions of PAAMePy polymers take place with beta-CD. The excimer-to-monomer fluorescence intensity ratio (I-E/I-M) was found to increase with the added amount of gamma-CD but not with beta-CD. This increase is justified on the basis of the increase of the GSD contribution. The photophysical behaviour was found to be dependent on the pH of the media, but with the absence of relevant interactions between CD and PAAMePy polymer at alkaline values. (C) 2007 Society of Chemical Industry.
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| 5. |
- Detta, Nicola, et al.
(författare)
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Melt electrospinning of polycaprolactone and its blends with poly(ethylene glycol)
- 2010
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 59:11, s. 1558-1562
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Tidskriftsartikel (refereegranskat)abstract
- Melt electrospinning is one aspect of electrospinning with relatively little published literature, although the technique avoids solvent accumulation and/or toxicity which is favoured in certain applications In the study reported, we melt-electrospun blends of poly(epsilon-caprolactone) (PCL) and an amphiphilic diblock copolymer consisting of poly(ethylene glycol) and PCL segments (PEG-block PCL) A custom-made electrospinning apparatus was built and various combinations of instrument parameters such as voltage and polymer feeding rate were investigated Pure PEG-block-PCL copolymer melt electrospinning did not result in consistent and uniform fibres due to the low molecular weight, while blends of PCL and PEG-block-PCL, for some parameter combinations and certain weight ratios of the two components, were able to produce continuous fibres significantly thinner (average diameter of ca 2 mu m) compared to pure PCL The PCL fibres obtained had average diameters ranging from 6 to 33 mu m and meshes were uniform for the lowest voltage employed while mesh uniformity decreased when the voltage was increased This approach shows that PCL and blends of PEG block-PCL and PCL can be readily processed by melt electrospinning to obtain fibrous meshes with varied average diameters and morphologies that are of interest for tissue engineering purposes.
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| 6. |
- El Ghaoui, Hanane, et al.
(författare)
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Bismuth complex catalysts for the in situ preparation of polycaprolactone/silicate bionanocomposites
- 2014
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 63:4, s. 709-717
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Tidskriftsartikel (refereegranskat)abstract
- Solvent-free, bismuth-catalysed in situ polymerization of caprolactone in the presence of layered silicates enables the formulation of a series of polycaprolactone/silicate bionanocomposites. Three organophilic montmorillonites obtained by cationic exchange reaction with tetrabutylammonium iodide, benzyltriethylammonium chloride and vinylbenzyltriphenylphosphonium chloride salts, respectively, were used as reinforcing reagents for these materials. The effects of clay and bismuth catalyst type (bismuth(III) acetate and triphenylbismuth) are discussed on the basis of composite morphologies and molecular weights of resulting polymers.
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| 7. |
- Gabilondo, Nagore, et al.
(författare)
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Property tailoring of phenol-formaldehyde matrices by control of reactant molar ratio and thermoplastic modification
- 2011
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 60:5, s. 851-858
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Tidskriftsartikel (refereegranskat)abstract
- High modulus, strength and thermal stability make phenol-formaldehyde resins (PFRs) interesting as matrices for nanocomposites. Four PFR matrices synthesized with different formaldehyde (F) to phenol (P) molar ratios were investigated, as well as the influence of thermoplastic modification on their mechanical properties. The effectiveness of a specific curing cycle for obtaining macrovoid- and microvoid-free specimens by controlling the thickness of samples is demonstrated. Fourier transform infrared spectroscopy results reveal that F content increases the presence of oxidized linkages as benzophenones and fully substituted aromatic structures. PFR matrices with highest F content present the highest values of main transition temperature and flexural modulus up to an F/P ratio of 1.8, revealing the achievement of a densely crosslinked and rigid structure. A selected PFR matrix was modified with 5, 10 and 15 wt% of two poly(vinyl butyral) (PVB) thermoplastics of differing molecular weight. Phase separation occurs before gelation in all cases leading to different morphologies, observed using atomic force microscopy and optical microscopy, depending on PVB content: PVB-rich particles in PFR-richmatrix for 5 wt% and co-continuous dual morphology for 10 and 15 wt% for both PVBs. Strength improvement is achieved for PFR matrices modified with 5 wt% of PVB associated with a tailored particulate morphology with a particle size of around 1.2 mu m. Finally, 5 and 10 wt% PVB-modified PFR materials exhibit a very high thermal stability with degradation temperatures very close to those for neat PFR matrix.
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| 8. |
- Gamiz Gonzalez, Maria Amparo, et al.
(författare)
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Synthesis of highly swellable hydrogels of water-soluble carboxymethyl chitosan and poly(ethylene glycol)
- 2017
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Ingår i: Polymer international. - : WILEY. - 0959-8103 .- 1097-0126. ; 66:11, s. 1624-1632
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Tidskriftsartikel (refereegranskat)abstract
- Highly swellable hydrogels were produced by crosslinking of high molecular weight carboxymethylated chitosan (CmCHT) with poly(ethylene glycol) (PEG) oligomers. The hydrogel swelling capacity could be controlled via the crosslinking density and ranged from 900% to 5600%. The hydrogels showed good homogeneity with a high interconnected porosity in the swollen state and with nanodomains rich in CmCHT and others rich in PEG diglycidyl ether. Oscillatory frequency sweep analysis showed a storage modulus of 27kPa for the hydrogel with the highest crosslinking density, which together with the exhibited enzyme degradability with lysozyme at 59days indicate that these hydrogels have potential use in delivery systems or soft tissue regeneration.
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| 9. |
- Gedefaw, Desta Antenehe, 1971, et al.
(författare)
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Conjugated polymers with polar side chains in bulk heterojunction solar cell devices
- 2014
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Ingår i: Polymer International. - : Wiley. - 1097-0126 .- 0959-8103. ; 63:1, s. 22-30
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Tidskriftsartikel (refereegranskat)abstract
- Two polymers with polar side chains, namely poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(5',8'-di-2-thienyl-(2',3'-bis(3''-(2-(2-methoxyethoxy)ethoxy)phenyl)quinoxaline))] (P1) and poly[2,7-(9,9-bis(2-(2-methoxyethoxy)ethyl)fluorene)-alt-5,5-(5',8'-di-2-thienyl-(2',3'-bis(3''-(2-(2-methoxyethoxy)-ethoxy)phenyl)quinoxaline))] (P2), were synthesized for solar cell application. A series of bulk heterojunction solar cells were systematically fabricated and characterized by varying the electron-acceptor materials, processing solvents and thickness of the active layer. The results show that P1, with a higher molecular weight and good film-forming properties, performed better. The best device showed an open circuit voltage of 0.87 V, a short circuit current of 6.81 mA cm(-2) and a power conversion efficiency of 2.74% with 1:4 polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) mixture using o-dichlorobenzene (o-DCB) as processing solvent. P2 on the other hand showed a poorer performance with chlorobenzene as processing solvent, but a much improved performance was obtained using o-DCB instead. Thus, an open circuit voltage of 0.80 V, short circuit current of 6.21 mA cm(-2) and an overall power conversion efficiency of 2.22% were recorded for a polymer:PCBM[70] mixing ratio of 1:4. This is presumably due to the improvement of the morphology of the active layer using o-DCB as processing solvent. (c) 2013 Society of Chemical Industry
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| 10. |
- Hobzova, R., et al.
(författare)
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Methacrylate hydrogels reinforced with bacterial cellulose
- 2012
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Ingår i: Polymer International. - : Wiley. - 1097-0126 .- 0959-8103. ; 61:7, s. 1193-1201
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Tidskriftsartikel (refereegranskat)abstract
- Composite hydrogels consisting of nanofibrous bacterial cellulose (BC) embedded in a biocompatible polymeric matrix of various methacrylates were synthesized by UV polymerization using the ever-wet technique. The effect of monomer(s) type and ratio, system dilution at polymerization, monomer(s) hydrophilicity, crosslink density and cellulose/hydrogel ratio was investigated. The effect of BC reinforcement on equilibrium swelling depends on whether the neat gel swells more when brought into contact with water. The major improvement achieved by introduction of 1%2% BC concerns mechanical properties. Compared with neat gels, the storage shear modulus G' increased by a factor 10-20, and the loss part G? also rose significantly. The compression modulus ranged from 2 to 5.5 MPa for composites swollen to equilibrium (20-70 wt% water). The BC-hydrogel composites are considered for application in the tissue engineering area.
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| 11. |
- Jiang, Zhiping, et al.
(författare)
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Fine tuning the hydrophobicity of counter-anions to tailor pore size in porous all-poly(ionic liquid) membranes
- 2019
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 68:9, s. 1566-1569
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Tidskriftsartikel (refereegranskat)abstract
- Charged porous polymer membranes (CPMs) emerging as a multifunctional platform for diverse applications in chemistry, materials science and biomedicine have been attracting widespread attention. Fabrication of CPMs in a controllable manner is of particular significance for optimizing their function and maximizing practical values. Herein, we report the fabrication of CPMs exclusively from poly(ionic liquid)s (PILs), and their pore size and wettability were precisely tailored by rational choice of counter-anions. Specifically, a stepwise subtle increase in hydrophobicity of the counter-anions by extending the length of fluorinated alkyl substituents, i.e. from bis(trifluoromethane sulfonyl)imide to bis(pentafluoroethane sulfonyl)imide and bis(heptafluoropropane sulfonyl)imide, decreased the average pore size gradually from 1546 to 157 and 77 nm, respectively. Meanwhile, the corresponding water contact angles increased from 90 degrees to 102 degrees and 120 degrees. The sensitive control over the porous architectures and surface wettability of CPMs by systematic variation of anion hydrophobicity provides solid proof of the impact of PIL anions on CPM structure.
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| 12. |
- Li, Jing, et al.
(författare)
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Preparation and properties of modified graphene oxide incorporated waterborne polyurethane acrylate
- 2019
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Ingår i: Polymer international. - : Society of Chemical Industry. - 0959-8103 .- 1097-0126. ; 68:6, s. 1091-1101
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a new modifier (KPG) was prepared by modifying graphene oxide with gamma-glycidoxypropyl trimethoxysilane (KH560) and polydimethylsiloxane (PDMS). KPG was in turn added to aqueous urethane acrylate for the fabrication of waterborne polyurethane polyacrylate emulsion modified with KH560-PDMS composite (KPG/WPUA). Textural characterizations of the KPG/WPUA coating were achieved via Fourier transform infrared, SEM, TGA and AFM techniques, which revealed that the KPG/WPUA film possessed a smooth surface. The synthesized KPG/WPUA films were tested for mechanical properties, hydrophobicity and acid/water corrosion performance which suggested their highly hydrophobic surface. KPG/WPUA with 0.1% KPG showed a contact angle of 118.35 degrees, 30.35 degrees higher than that of pristine WPUA. The KPG/WPUA film exhibited higher thermal stability, i.e. a 5% weight loss temperature of 305 degrees C, which was 30 degrees C higher than that of pristine WPUA film. The Young's modulus and elongation at break of the KPG/WPUA film were 34.1 MPa and 74.88% respectively, which were higher than that of WPUA film. Furthermore, KPG/WPUA films exhibited greater resistance (without obvious blistering and the white spotting phenomenon) to H2O2, HCl and water corrosion than pristine WPUA. The superior performance of KPG/WPUA films was attributed to the network chain structure formed upon the introduction of KPG into WPUA. The outstanding performance of KPG/WPUA films in terms of mechanical properties, thermal stability and high resistance to acidic and water corrosion makes them interesting alternative contenders for target applications. (c) 2019 Society of Chemical Industry
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| 13. |
- Mauri, Massimiliano, 1987, et al.
(författare)
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Click chemistry-type crosslinking of a low-conductivity polyethylene copolymer ternary blend for power cable insulation
- 2020
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Ingår i: Polymer International. - : Wiley. - 1097-0126 .- 0959-8103. ; 69:4, s. 404-412
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Tidskriftsartikel (refereegranskat)abstract
- High-voltage direct-current power cables are vital for the efficient transport of electricity derived from renewable sources of energy. The most widely used material for high-voltage power cable insulation - low-density polyethylene (LDPE) - is usually crosslinked with peroxides, a process that releases unwanted by-products. Hence, by-product-free crosslinking concepts that mitigate the associated increase in electrical conductivity are in high demand. Click chemistry-type crosslinking of polyethylene copolymer mixtures that contain glycidyl methacrylate and acrylic acid co-monomers is a promising alternative, provided that the curing reaction can be controlled. Here, we demonstrate that the rate of the curing reaction can be adjusted by tuning the number of epoxy and carboxyl groups. Both dilution of copolymer mixtures with neat LDPE and the selection of copolymers with a lower co-monomer content have an equivalent effect on the curing speed. Ternary blends that contain 50 wt% of neat LDPE feature an extended extrusion window of up to 170 degrees C. Instead, at 200 degrees C rapid curing is possible, leading to thermosets with a low direct-current electrical conductivity of about 10(-16) S cm(-1) at an electric field of 20 kV mm(-1) and 70 degrees C. The conductivity of the blends explored here is comparable to or even lower than values measured for both ultraclean LDPE and a peroxide-cured commercial crosslinked polyethylene grade. Hence, click chemistry curing represents a promising alternative to radical crosslinking with peroxides. (c) 2019 Society of Chemical Industry
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| 14. |
- Michalak, Michal, et al.
(författare)
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Polyhydroxyalkanoate-based drug delivery systems
- 2017
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Ingår i: Polymer international. - : WILEY. - 0959-8103 .- 1097-0126. ; 66:5, s. 617-622
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Forskningsöversikt (refereegranskat)abstract
- Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA-based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini-review presents some recent scientific developments in the preparation of functionalized PHAs, PHA-drug and PHA-protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications.
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| 15. |
- Peltzer, Mercedes, et al.
(författare)
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Surface modification of cellulose nanocrystals by grafting with poly(lactic acid)
- 2014
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 63:6, s. 1056-1062
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Tidskriftsartikel (refereegranskat)abstract
- The use of biopolymers obtained from renewable resources is currently growing and they have found unique applications as matrices and/or nanofillers in 'green' nanocomposites. Grafting of polymer chains to the surface of cellulose nanofillers was also studied to promote the dispersion of cellulose nanocrystals in hydrophobic polymer matrices. The aim of this study was to modify the surface of cellulose nanocrystals by grafting from L-lactide by ring-opening polymerization in order to improve the compatibility of nanocrystals and hydrophobic polymer matrices. The effectiveness of the grafting was evidenced by the long-term stability of a suspension of poly(lactic acid)-grafted cellulose nanocrystals in chloroform, by the presence of the carbonyl peak in modified samples determined by Fourier transform infrared spectroscopy and by the modification in C1s contributions observed by X-ray photoelectron spectroscopy. No modification in nanocrystal shape was observed in birefringence studies and transmission electron microscopy.
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| 16. |
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| 17. |
- Stålgren, Johan Jim Roger, et al.
(författare)
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Synthesis and characterization of cationic polymeric salts : derivatives of 2-(dimethylamino)ethyl-2-methacrylate, containing oligomeric ethylene oxide side-chains
- 2003
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 52:3, s. 399-405
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Tidskriftsartikel (refereegranskat)abstract
- A novel set of cationic polyelectrolytes has been prepared. The polyelectrolytes have a high cationicity with each segment carrying one positively charged quaternary ammonium group. The polyelectrolytes also contain grafted oligo(ethylene oxide) (110) chains. The grafted EO chains are, according to NMR measurements, six units long. The graft density of EO chains has been varied and polymers having approximately 100%, 20% and 10% of the segments with a grafted EO chain have been prepared. The obtained products were characterized using H-1 and C-13 NMR spectroscopy. Aqueous solutions of the cationic polymers were characterized by dynamic light-scattering (DLS) measurements. It was found to be important to include a radical inhibitor to prevent crosslinking reactions during isolation and purification. In general the DLS measurements showed a bimodal size distribution. The majority of the polymers (about 75wt%) were found to have a hydrodynamic radius of 6-8 mn, with the remaining polymers being dominated by a fraction with a hydrodynamic radius in the range 120-140nm.
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| 18. |
- Sun, Hui, et al.
(författare)
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Facile polyester surface functionalization via hydrolysis and cell-recognizing peptide attachment
- 2006
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Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 55:11, s. 1336-1340
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Tidskriftsartikel (refereegranskat)abstract
- Facile surface modification of biodegradable polycaprolactone via alkali hydrolysis and subsequent attachment of a cell-recognizing peptide to the hydrolysed polymer surface is reported. Surface hydrolysis was carried out in sodium hydroxide solution. The modification was studied with regard to hydrolysis time, temperature and alkaline concentration. A cell-recognizing peptide was covalently attached to the hydrolysed polymer surface. Contact angle measurements, X-ray photoelectron spectroscopy and ultraviolet spectroscopy were used to characterize the modified surface and to confirm the occurrence of the coupling reaction.
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| 19. |
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| 20. |
- Feas, Xesus, et al.
(författare)
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Molecularly imprinted polyallylamine hydrogels: another reassessment
- 2010
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Ingår i: Polymer International. - : Wiley. - 0959-8103. ; 59:1, s. 11-15
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Tidskriftsartikel (refereegranskat)abstract
- Researchers in the scientific community actively discuss the fact that polymer hydrogels synthesized by crosslinking polly(allylamine hydrochloride) (PAH) with epichlorohydrin (EPI) in the presence of D-glucose-6-phosphate monobarium salt do not show or show imprinting on the molecular level. In the work reported here, a polymer hydrogel was synthesized in the presence of flumequine (FQ) by crosslinking PAH with EPI in an aqueous system. The extent of FQ binding was assessed using liquid chromatography coupled with laser-induced fluorescence detection. A hydrogel-imprinting system was found to display FQ selectivity in binding assays (75.1 and 41.9%) compared with hydrogel formed in the absence of a template (41.6 and 20.4%). High-magnification scanning electron microscopy (SEM) images show that both of the hydrogels are highly ordered, exhibiting a 'honeycomb' pattern distribution. For the effect of the template molecule in the polymer structure (i.e. the imprinting effect in hydrogel morphology), appreciable differences were observed for images obtained. The non-imprinted polymer had a uniform, smoothly shaped surface. By contrast, the hydrogel molecular imprinting polymer surface was more globular. This difference was likely caused by the structure of the target molecule. Binding experiment results correlate with surface morphology, as analysed using SEM, and indicate that imprinted hydrogels have recognizable cavities with an affinity for used FQ from the imprint. (C) 2009 Society of Chemical Industry
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| 21. |
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| 22. |
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| 23. |
- Ubhayasekera, Wimal
(författare)
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Structure and function of chitinases from glycoside hydrolase family 19
- 2011
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Ingår i: Polymer International. - : Wiley. - 0959-8103. ; 60:6, s. 890-896
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Forskningsöversikt (refereegranskat)abstract
- Glycoside hydrolase family 19 chitinases are found in plants, bacteria and viruses, playing various roles. Plant chitinases are important for defence and development, whereas bacterial examples are useful for nutrition. The available structural studies show that family 19 enzymes are highly alpha-helical bi-lobed structures with a wide cleft lined by conserved residues important for catalysis and substrate binding. Class I and II plant chitinases possess loops which are absent in class IV and/or bacterial chitinases. One of the loops seems to retain a significant function. These inverting endochitinases demonstrate a possible opening-closing mechanism of the catalytic cleft during chitin hydrolysis due to loop movements. However, complex structures with inhibitors and/or substrate/product analogues are required for a deeper understanding of these enzymes. (C) 2011 Society of Chemical Industry
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