From viral barriers to proton conductors – novel applications for polymeric membranes

Novel applications for polymeric membranes which address the needs of health care industry and development of alternative energy sources are reviewed in this paper. Polyolefin membranes made by thermally-induced separation process can be used as barriers against biological pathogens and splashes of harmful liquid chemicals, or as separators in lithium ion batteries, which can provide an increased margin of safety by shutting down the electrical current in case of battery overheating. Asymmetric membranes made by a combination of immersion precipitation and photopolymerization can be used as proton exchange membranes in fuel cells. Modifications of this novel process could be used to make membranes for other interesting applications

pH-sensitive membranes with crosslinked poly(acrylic acid) hydrogel for controlled delivery

Polymeric pH-sensitive membranes and hydrogels are interesting materials for the controlled delivery of chemical agents triggered by external stimuli. In this contribution, we present a novel membrane design consisting of a polyethersulfone polymeric base and a crosslinked poly(acrylic acid) hydrogel containing pH-responsive carboxyl groups. Membranes were prepared using the modified traditional liquid phase inversion process. Solutions containing all membrane precursors were cast on a glass plate and cured by UV irradiation. UV curing was followed by immersion into the water bath to achieve phase separation and solidification. Obtained membranes exhibited high ion-exchange capacity and a moderate swelling degree dependent on the crosslinker properties. Studies of membrane loading with methylene blue and subsequent release of methylene blue from the membrane into the alkaline and acidic buffered solutions demonstrated pH-dependent delivery kinetics

From viral barriers to proton conductors – novel applications for polymeric membranes

Novel applications for polymeric membranes which address the needs of health care industry and development of alternative energy sources are reviewed in this paper. Polyolefin membranes made by thermally-induced separation process can be used as barriers against biological pathogens and splashes of harmful liquid chemicals, or as separators in lithium ion batteries, which can provide an increased margin of safety by shutting down the electrical current in case of battery overheating. Asymmetric membranes made by a combination of immersion precipitation and photopolymerization can be used as proton exchange membranes in fuel cells. Modifications of this novel process could be used to make membranes for other interesting applications

Corporate social responsibility as a tool for smart, sustainable and inclusive growth

The recently adopted Strategy for the economic and social development of the EU - Europe Strategy 2020, recognizes the concept of the Corporate Social Responsibility (CSR) as one of the tools for the achievement of a smart, sustainable and inclusive growth. Although the integration of CSR concept into business strategies is made on voluntary bases, governments, civil sector, media and academia have an important role in its promotion. The aim of this paper is to analyse the role that CSR plays in the socio-economic development focusing on Serbia. While the Government perceives the importance of CSR for Serbian socioeconomic development, it is noticeable that pressure on companies to undertake socially responsible activities made by media, NGOs, consumers and business partners is not remarkable. In addition, the business community still does not have enough CSR initiatives that would be both beneficial to the community and profitable for companies. The paper argues that education on CSR of the managers and the broader public is essential in raising the awareness of the benefits that CSR offer. Consequently, it would lead towards the wider implementation of CSR in Serbia

Poslovna etika i društvena odgovornost u upravljanju ljudskim resursima

Autori ovog rada, pre svega, nastoje da utvrde ulogu poslovne etike i koncepta društvene odgovornosti u upravljanju ljudskim resursima, a potom vrše analizu poslovne prakse u Srbiji i Bosni i Hercegovini po pitanju odgovornog odnosa prema zaposlenima, fokusirajući se prvenstveno na poštovanje zakonom garantovanih prava radnika, ali i na aktivnosti koje prevazilaze poštovanje zakona. Autori smatraju da postoje argumenti u prilog zahteva da menadžeri treba da poštuju prava zaposlenih, kao i da kompanije imaju odgovornost prema svojim zaposlenima, te da njihove ciljeve treba da uzmu u obzir prilikom definisanja ciljeva kompanije. Uspostavljanje međunarodne inicijative u vidu Globalnog dogovora UN za poštovanje ljudskih i radnih prava, zaštite prirodne okoline i borbe protiv korupcije dodatno potvrđuje neophodnost odgovornog i etičnog upravljanja ljudskim resursima. Srbija i Bosna i Hercegovina su potpisnice ovog Dogovora. Takođe, obe zemlje uspostavile su zakonski okvir koji garantuje zaštitu ljudskih i radnih prava. Međutim, u poslovnoj praksi dveju zemalja primetni su brojni primeri kršenja radnih prava. Takođe, u obe zemlje nedostaju društveno odgovorne aktivnosti prema zaposlenima koje prevazilaze zakonom definisane obaveze

Photopolymerizable monomer formulations for nanoporous proton conducting membranes

Several monomers and crosslinker in a broad range of concentrations in water and 1-Methyl-2-pyrrolidone (NMP) respectively were screened for their mechanical properties, water uptake and conductivity by photo polymerization with a polar photo initiator in porous membranes made of polypropylene and polyethersulfone respectively. As conductive polymer, primarily poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) and poly(2-sulfoethyl methacrylate) (PSEM) respectively as well as polymers of phosphonic acid containing monomers or newly synthesized monomers were used. The conductive monomers were crosslinked with varying hydrophobic and hydrophilic multifunctional monomers like N,N'-methylene bisacrylamide (MBA), 2-Propenoic acid, 2-methyl-, 1,1'-(1,10-decanediyl) ester (D3MA) or polyethyleneglycol diacrylates with two varying chainlengths (PEG-DA700, PEG-DA330). Furthermore several new multifunctional crosslinker with enhanced thermal and ageing stability have been synthesized and tested.\ud The advantage of several different building blocks with known characteristics is the possibility to tune the polymer to special needs of an application. For example, some polymer compositions have good conductivity at lower temperatures whereas other polymers develop better properties at elevated temperatures

Novel crosslinkers for high performance poly-AMPS-based proton exchange membranes for fuel cells

Polymer electrolyte fuel cells (PEFC) gained a lot of interest in recent years as a potential solution for an eco-friendly energy. Proton exchange membranes (PEM) are one of the main components of PEFCs and require mechanical and chemical stability to ensure high proton conductivity and effective separation of anode and cathode under challenging conditions. Best commercial membranes made from sulfonated fluoropolymers, such as Nafion®, are rather expensive. To improve fuel cell performance at a lower cost, 2-acrylamido-2-methylpropane sulfonic acid (AMPS) was investigated recently. 1 Since polyAMPS (PAMPS) excessively swells or even dissolves in water, we investigated several commercial crosslinkers and new multifunctional monomers (Fig. 1) to decrease swelling by crosslinking. AMPS, crosslinker and photoinitiator were dissolved in water and N-methyl-2-pyrrolidone (NMP), respectively. To facilitate conductivity measurements and handling of crosslinked PAMPS formulations after UVinitiated radical polymerization, they were constrained within a porous membrane using a procedure described by Zhou et al. 2 We tested several commercial crosslinkers and according to these results we developed new crosslinkers with enhanced hydrolytical stability and conductivity. In contrast to the commercial crosslinkers, where conductivity increased with increasing amount of crosslinker, our new acrylamide based crosslinkers needed only very low concentrations. They could achieve more than 2.5 times the conductivity of Nafion with only 5 wt% crosslinker. We used this novel crosslinkers to integrate them into asymmetric membranes with interpenetrating proton-conducting morphology for enhanced methanol barrier properties. 3 First results of their performance compared to Nafion will be presented. The research leading to these results has received funding from the European Community's FP7- NMP Programme, under the Project Acronym MultiPlat with Grant Agreement: N 228943 and the Austrian Federal Ministry of Science and Research. The authors would like to thank 3M for PP membrane samples and Ciba SC, Huntsman, Ivoclar Vivadent and Sartomer for samples of photoinitiator and crosslinker. 1 a) Qiao, J., et al., Journal of Materials Chemistry 2005, 15 (41), 4414-4423. b)Diao, H., et al., Macromolecules 43 (15), 6398-6405. 3 Zhou, J., et al., Journal of Membrane Science 2005, 254 (1-2), 89-99. 4 Radovanovic, P., et al., Journal of Membrane Science 2012, 401-402, 254-261

Asymmetric sol-gel proton-conducting membrane

Proton-conducting membranes with interpenetrating polymer network morphology have gained attention in recent years for potential replacement of standard Nafion membranes in direct methanol fuel cells. These membranes generally consist of fine interpenetrating domains of proton-conducting and mechanically-supporting polymer phases, which often leads to improvements in mechanical strength and methanol barrier properties. Asymmetric sol-gel membranes comprising proton-conducting channels of cross-linked sulfonic acid functionalized ionomers embedded within a matrix of thermally-resistant, glassy polymer were prepared by photopolymerization starting from a polymer solution and evaluated in our laboratories. These membranes have an integral top skin layer with fine biomimetic proton-conducting channels, which provides a barrier against methanol crossover, on top of a coarser proton-conducting support. Conductivity of asymmetric membranes over a range of initial polymer concentrations and ion-exchange capacities (IEC) was just slightly lower than for the corresponding symmetric membranes. Methanol barrier properties of asymmetric sol-gel membranes were better than that of Nafion 115 membrane. The crosslinking agent functionality had a major effect on membrane conductivity. Use of trifunctional crosslinking agents resulted in significantly higher conductivities than those obtained with bifunctional agents, even surpassing the conductivity of Nafion membranes

Multifunctionalized Self-supported (Nano) Membranes as Integrated Platform for Plasmonic Metamaterials

We considered the possibility to fabricate multifunctional nanocomposite membranes as a platform for plasmonic metamaterials, simultaneously incorporating pores, built-in functional groups and active nanoparticles. To this purpose we combined lamination and inclusion of nanofillers into the membrane host. For the basic material we chose macroporous crosslinked copolymers based on glycidyl methacrylate (GMA). The epoxy group present in GMA molecule is readily transformed into various functional groups that further serve as affinity enhancers, ensuring the usability of the membranes as pre-concentrators of selected agents in plasmonic sensors. To form GMA-based membranes we used a recently proposed method combining the traditional immersion precipitation with photopolymerization and crosslinking of functional monomers. Further functionalization is obtained by in-situ formation of noble metal nanoparticles directly within the GMA host. In this way membranes with simultaneous plasmonic, adsorbent and catalytic functionality are obtained. We considered the use of the our structures for plasmonic chemical sensors where separator, pre-concentrator and binding agent are integrated with the plasmonic crystal, as well as for plasmonic enhancement of photocatalytic reactions in microreactors. Our approach gives a highly tailorable element compatible with microelectromechanical systems (MEMS) technologies and readily transferable across platforms

Novel crosslinkers for high performance poly-AMPS-based proton exchange membranes for fuel cells

Polymer electrolyte fuel cells (PEFC) gained a lot of interest in recent years as a potential solution for an eco-friendly energy. Proton exchange membranes (PEM) are one of the main components of PEFCs and require mechanical and chemical stability to ensure high proton conductivity and effective separation of anode and cathode under challenging conditions. Best commercial membranes made from sulfonated fluoropolymers, such as Nafion®, are rather expensive. To improve fuel cell performance at a lower cost, 2-acrylamido-2-methylpropane sulfonic acid (AMPS) was investigated recently. 1 Since polyAMPS (PAMPS) excessively swells or even dissolves in water, we investigated several commercial crosslinkers and new multifunctional monomers (Fig. 1) to decrease swelling by crosslinking. AMPS, crosslinker and photoinitiator were dissolved in water and N-methyl-2-pyrrolidone (NMP), respectively. To facilitate conductivity measurements and handling of crosslinked PAMPS formulations after UVinitiated radical polymerization, they were constrained within a porous membrane using a procedure described by Zhou et al. 2 We tested several commercial crosslinkers and according to these results we developed new crosslinkers with enhanced hydrolytical stability and conductivity. In contrast to the commercial crosslinkers, where conductivity increased with increasing amount of crosslinker, our new acrylamide based crosslinkers needed only very low concentrations. They could achieve more than 2.5 times the conductivity of Nafion with only 5 wt% crosslinker. We used this novel crosslinkers to integrate them into asymmetric membranes with interpenetrating proton-conducting morphology for enhanced methanol barrier properties. 3 First results of their performance compared to Nafion will be presented. The research leading to these results has received funding from the European Community's FP7- NMP Programme, under the Project Acronym MultiPlat with Grant Agreement: N 228943 and the Austrian Federal Ministry of Science and Research. The authors would like to thank 3M for PP membrane samples and Ciba SC, Huntsman, Ivoclar Vivadent and Sartomer for samples of photoinitiator and crosslinker. 1 a) Qiao, J., et al., Journal of Materials Chemistry 2005, 15 (41), 4414-4423. b)Diao, H., et al., Macromolecules 43 (15), 6398-6405. 3 Zhou, J., et al., Journal of Membrane Science 2005, 254 (1-2), 89-99. 4 Radovanovic, P., et al., Journal of Membrane Science 2012, 401-402, 254-261