| 1. |
- Aguilar-Sanchez, Andrea, et al.
(författare)
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Waterborne nanocellulose coatings for improving the antifouling and antibacterial properties of polyethersulfone membranes
- 2021
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 620
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a waterborne nanocellulose coating process to change the surface characteristics and mitigate fouling of commercially available polyethersulfone (PES) microfiltration membranes. An extensive comparative study between nanoporous and nano-textured layers composed of cellulose nanocrystals (CNC) or TEMPO-oxidized cellulose nanofibrils (T-CNF), which were coated on the PES membrane by taking advantage of the electrostatic interactions between the PES substrate, a polyallylamine hydrochloride (PAHC1) anchoring layer, and the nanocellulose functional layer. Coated PES membranes exhibited decreased surface roughness and pore sizes as well as rejection of compounds with a M-w above 150 kDa, while the water permeability and mechanical properties of remained largely unaffected. The coatings improved the wettability as confirmed by a reduction of the contact angle by up to 52% and exhibited a higher negative surface charge compared to the uncoated membranes over a pH range of 4-8. A significant reduction in organic fouling was observed for the coated membranes demonstrated by bovine serum albumin (BSA) adsorption studies on T-CNF and CNC surfaces using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), UV-vis spectroscopy and FTIR mapping after exposing the membranes to dynamic adsorption of BSA. The T-CNF coating exhibited effective antibacterial action against Escherichia coli (E. coli) attributed to the pH reduction effect induced by the carboxyl groups; while CNC coatings did not show this property. This work demonstrates a simple, green, and easy-to-scale layer-by-layer coating process to tune the membrane rejection and to improve antifouling and antibacterial properties of commercially available membranes.
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| 2. |
- Finnveden, Maja, et al.
(författare)
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One-Component Thiol-Alkene Functional Oligoester Resins Utilizing Lipase Catalysis
- 2016
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Ingår i: Macromolecular Chemistry and Physics. - : John Wiley & Sons. - 1022-1352 .- 1521-3935.
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Tidskriftsartikel (refereegranskat)abstract
- Chemo-enzymatic methods are powerful tools for the synthesis of novel materials. By combining the flexibility of chemical synthesis and the high selectivity of enzymes, a variety of functional materials can be achieved. In the present study, a series of α,ω-thiol telechelic oligoesters with varying amount of internal alkenes are prepared using selective lipase catalysis and are subsequently cross-linked by thiol-ene chemistry yielding alkene functional networks. Due to the reactivity of thiols and alkenes almost all present thiol-ene systems consist of two components. This work demonstrates that selective lipase catalysis in combination with renewable monomers with internal alkenes is a promising system for achieving one-component thiol-alkene functional resins with good storage stability and a high degree of thiol end-groups. The developed chemo-enzymatic route yields polymer networks with tailored amount of alkene functionalities in the final thermoset, which facilitate further postmodification.
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| 3. |
- Johansson, Mats, 1961-, et al.
(författare)
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Biobased feedstock for novel coating systems
- 2017
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Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 254
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
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| 5. |
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| 6. |
- Nameer, Samer, et al.
(författare)
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Bio-based multifunctional fatty acid methyl esters as reactive diluents in coil coatings
- 2019
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Ingår i: Progress in organic coatings. - : Elsevier. - 0300-9440 .- 1873-331X. ; 136
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Tidskriftsartikel (refereegranskat)abstract
- The increased environmental awareness has driven academia and industry to utilize environmentally benign sources. An industrially available process that is effective in the coatings industry is the coil-coating process where sheet steel can be pre-coated. During this process volatile organic compounds (VOCs) are generated and incinerated for energy recovery. One way to minimize VOCs is to use a reactive diluent i.e. a molecule that acts both as a solvent as well as chemically react into the final coating upon curing. Fatty acid methyl esters obtained from renewable resources such as vegetable oils are suitable candidates as reactive diluents. In this paper epoxidized fatty acid methyl esters (e-FAMEs) obtained from epoxidized linseed oil where compared with fatty acid methyl esters (FAMEs) obtained from rapeseed oil as reactive diluents in coil-coating formulations. Coil-coating formulations were followed by real-time Fourier transform infrared spectroscopy (RT-FTIR) in order to evaluate the e-FAMEs or the FAMEs reactivity in the coating system. In addition, coil-coating formulation containing e-FAME or FAME where cured in a pilot scale simulated coil-coating process. Moreover, thermal properties of the final coatings were evaluated by differential scanning calorimetry (DSC).
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| 7. |
- Nameer, Samer, et al.
(författare)
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Biobased Cationically Polymerizable Epoxy Thermosets from Furan and Fatty Acid Derivatives
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:7, s. 9442-9450
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Tidskriftsartikel (refereegranskat)abstract
- In the pursuit of environmentally friendly building blocks in polymer chemistry the utilization of biobased monomers is highly desired. In the present study, the biobased monomer 2,5-furandicarboxylic acid (FDCA) has been extended into epoxy thermosets. The study presents the synthesis of diallyl furan-2,5-dicarboxylate (DAFDC) followed by an epoxidation of the allyls to form diglycidyl furan-2,5-dicarboxylate (DGFDC). DGFDC was then copolymerized in both stoichiometric and off-stoichiometric ratios with epoxidized fatty methyl esters to form a range of thermosets. The cross-linking reaction was either thermally or UV-induced cationic polymerization utilizing onium salt initiators where the reactivity was studied by DSC and real-time fourier transform infrared analysis. Furthermore, the structure-property relationships of the final thermosets were determined by dynamic mechanical thermal analysis revealing a possibility to tune the properties over a wide range. In addition thermosets were made from diglycidyl Bisphenol-A (DGEBA) with epoxidized fatty methyl esters made for comparative purposes.
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| 8. |
- Nameer, Samer
(författare)
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Exploring fatty acid derivatives from renewable resources as raw materials for coating applications
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the work presented herein, epoxy fatty acid derivatives were explored in the formation of thermosets for coating applications. The epoxy fatty acid derivatives were obtained from renewable resources such as birch tree bark and epoxidized linseed oil. The birch bark was used to isolate 9,10-epoxy-18-hydroxyoctadecanoic acid (EFA) and the epoxidized linseed oil was used to retrieve methyl stearate and 3 different epoxy methyl esters: epoxy methyl oleate/linoleate/linolenate (EMO/EMLO/EMLEN). The obtained epoxy fatty acid derivatives were used in resin formulations together with other reactants or in the synthesis of multifunctional oligomer resins using enzyme catalysis. All resins were cured using different polymerization techniques to form thermosets with a wide variety of properties.Multifunctional oligomer resin were synthesized using Candida Antarctica lipase-B (CALB) as enzyme. It was demonstrated that the synthesis was efficient and the oligomers were obtained from “one-pot” route. In addition, the selectivity of CALB was useful in preserving a variety of functional groups (epoxides, alkenes and thiols) in the final oligomers. The oligomers were cross-linked by either thiol-ene chemistry or cationic polymerization resulting in functional thermosets. It was further shown that surface properties of the cured thermosets could be changed by using post-functionalization.Pure fatty acid methyl esters cure into soft materials. An approach in increasing the thermal and mechanical properties was investigated. The 3 different epoxy functional methyl esters together with a furan-2,5-dicarboxylic acid derivative were investigated in the formation of thermosets. Glass transition temperature (Tg) below 0 °C and above 100 °C were obtained by varying the stoichiometric feed of the reactants.The thermal curing of EFA as a one-component system was investigated by model studies showing that a self-catalyzed process occur. EFA thermally cures into a thermoset without the need of an added catalyst. Furthermore, the thermoset showed adhesive properties.Crude mixture containing methyl stearate, EMO, EMLO and EMLEN obtained from epoxidized linseed oil were investigated as reactive diluent in coil-coatings. The mixture was also compared with commercially available reactive diluents such as fatty acid methyl esters (FAME) obtained from rapeseed oil. The results obtained showed that more fatty methyl esters could be incorporated in the final thermoset when using the epoxidized linseed oil fatty acid derivatives.Real-time Fourier-transform infrared spectroscopy (RT-FTIR) was used during most of the work presented in the thesis and proved to be a powerful tool in monitoring the different reactions and comparing relative reaction rates.
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| 9. |
- Nameer, Samer, et al.
(författare)
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Fully bio-based aliphatic thermoset polyesters via self-catalyzed self-condensation of multifunctional epoxy monomers directly extracted from natural sources
- 2017
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Ingår i: Journal of Coatings Technology Research. - : Springer. - 1945-9645 .- 1547-0091 .- 1935-3804. ; 14:4, s. 757-765
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Tidskriftsartikel (refereegranskat)abstract
- The use of bio-based raw material is regarded as a sustainable way to address environmental concerns. A naturally occurring monomer, 9,10-epoxy-18-hydroxyoctadecanoic acid (EFA), was retrieved from outer birch bark. A series of model experiments revealing relative reaction rates for epoxide, carboxylic acid, and alcohol functional groups was investigated. Real-time Fourier transform infrared spectroscopy and nuclear magnetic resonance were used to follow the different model experiments. The results on the model systems were then compared to the thermoset formation of thermally cured EFA. Finally, the adhesive properties of crosslinked EFA on different substrates were evaluated.
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| 10. |
- Nameer, Samer, et al.
(författare)
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One-pot enzyme-catalyzed synthesis of dual-functional polyester macromers towards surface active hydrophobic films
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Selective enzyme catalysis is a valuable tool for the processing of monomers into value-added materials. In the present study natural resources were used to retrieve an ω-hydroxy fatty acid monomer containing an epoxide functionality. A procedure was developed for the synthesis of dual-functional oligomers by utilizing lipase catalysis in a one-pot synthesis route. The chemoselectivity of the enzyme allowed addition of thiol monomers to the retrieved epoxy monomers, without harming the epoxides, achieving a thiol-epoxy functional polyester resin. The synthesis reached full conversion (>99 %) after 8 h. It was possible to selectively crosslink the resin, through UV-initiated cationic polymerization of the epoxides into thiol-functional thermosets. The curing performance was followed in situ by Real-Time FTIR. The thiol groups on the surface of the film were accessible for post-modification.
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