scholarly journals Chitosan-Sulfated Titania Composite Membranes with Potential Applications in Fuel Cell: Influence of Cross-Linker Nature

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1125
Author(s):  
Andra-Cristina Humelnicu ◽  
Petrisor Samoila ◽  
Mihai Asandulesa ◽  
Corneliu Cojocaru ◽  
Adrian Bele ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Stability ◽  
Dielectric Spectroscopy ◽  
Composite Membranes ◽  
Mechanical And Thermal Properties ◽  
Fenton Reagent ◽  
Sulfated Titania ◽  
Electrolyte Membranes ◽  
Potential Applications ◽  
Cross Linker

Chitosan-sulfated titania composite membranes were prepared, characterized, and evaluated for potential application as polymer electrolyte membranes. To improve the chemical stability, the membranes were cross-linked using sulfuric acid, pentasodium triphosphate, and epoxy-terminated polydimethylsiloxane. Differences in membranes’ structure, thickness, morphology, mechanical, and thermal properties prior and after cross-linking reactions were evaluated. Membranes’ water uptake capacities and their chemical stability in Fenton reagent were also studied. As proved by dielectric spectroscopy, the conductivity strongly depends on cross-linker nature and on hydration state of membranes. The most encouraging results were obtained for the chitosan-sulfated titania membrane cross-linked with sulfuric acid. This hydrated membrane attained values of proton conductivity of 1.1 × 10−3 S/cm and 6.2 × 10−3 S/cm, as determined at 60 °C by dielectric spectroscopy and the four-probes method, respectively.

scholarly journals Effect of the Cross-Linking Density on the Swelling and Rheological Behavior of Ester-Bridged β-Cyclodextrin Nanosponges

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 478
Author(s):  
Gjylije Hoti ◽  
Fabrizio Caldera ◽  
Claudio Cecone ◽  
Alberto Rubin Pedrazzo ◽  
Anastasia Anceschi ◽  
...  
Keyword(s):  
Scale Up ◽  
Future Application ◽  
Cross Linking ◽  
Synthesis Reaction ◽  
Dependent Behavior ◽  
Cyclodextrin Nanosponges ◽  
Potential Applications ◽  
Cross Linker ◽  
The Cross ◽  
Shed Light

The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged NSs based on β-cyclodextrin (β-CD) and different quantities of pyromellitic dianhydride (PMDA), used as a cross-linking agent in stoichiometric proportions of 2, 3, 4, 5, 6, 7, 8, 9, and 10 moles of PMDA for each mole of CD, were synthesized and characterized in terms of swelling and rheological properties. The results, from the swelling experiments, exploiting Flory–Rehner theory, and rheology, strongly showed a cross-linker content-dependent behavior. The study of cross-linking density allowed to shed light on the efficiency of the synthesis reaction methods. Overall, our study demonstrates that by varying the amount of cross-linking agent, the cross-linked structure of the NSs matrix can be controlled effectively. As PMDA βCD-NSs have emerged over the years as a highly versatile class of materials with potential applications in various fields, this study represents the first step towards a full understanding of the correlation between their structure and properties, which is a key requirement to effectively tune their synthesis reaction in view of any specific future application or industrial scale-up.

Composite proton exchange membranes produced using chitosan and kaolin solvent-free fluid

2020 ◽  
Vol 40 (6) ◽  
pp. 495-506
Author(s):  
Chun-Chun Huang ◽  
Syang-Peng Rwei ◽  
Yun-Shao Huang ◽  
Yao-Chi Shu
Keyword(s):  
Direct Methanol Fuel Cells ◽  
Composite Membranes ◽  
Proton Exchange ◽  
Solvent Free ◽  
Free Fluid ◽  
Exchange Method ◽  
Polymer Substrates ◽  
Practical Applications ◽  
Inorganic Substances ◽  
Electrolyte Membranes

AbstractIn this study, composite membranes produced by combining both biopolymer chitosan (CS) and kaolin solvent-free fluid (kaolin-SF) were used as substitutes for the electrolyte membranes in direct-methanol fuel cells. To improve the interfacial morphologies between organic and inorganic substances, kaolin-SF was prepared using the ion exchange method. Subsequently, kaolin-SF of various doping proportions was mixed with CS crosslinked with sulfuric acid to produce thin membranes. The results of heat exhaustion and scanning electron microscope image analysis indicated that kaolin-SF was successfully doped into the CS polymer substrates, and this addition enhanced the thermal stability and mechanical properties of the CS polymer substrates. As long as the concentration of kaolin-SF was below 5 wt.%, the water absorption rate and proton conductivity of the CS/kaolin-SF composite membranes increased along with the kaolin-SF content. These results indicate that CS/kaolin-SF composite membranes are suitable for practical applications.

scholarly journals Reversible Protein Capture and Release by Redox-Responsive Hydrogel in Microfluidics

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 267
Author(s):  
Chen Jiao ◽  
Franziska Obst ◽  
Martin Geisler ◽  
Yunjiao Che ◽  
Andreas Richter ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Disulfide Bonds ◽  
Stimuli Responsive ◽  
Disulfide Exchange ◽  
Protein Capture ◽  
Wide Range ◽  
Redox Responsive ◽  
Potential Applications ◽  
Capture And Release ◽  
Cross Linker

Stimuli-responsive hydrogels have a wide range of potential applications in microfluidics, which has drawn great attention. Double cross-linked hydrogels are very well suited for this application as they offer both stability and the required responsive behavior. Here, we report the integration of poly(N-isopropylacrylamide) (PNiPAAm) hydrogel with a permanent cross-linker (N,N′-methylenebisacrylamide, BIS) and a redox responsive reversible cross-linker (N,N′-bis(acryloyl)cystamine, BAC) into a microfluidic device through photopolymerization. Cleavage and re-formation of disulfide bonds introduced by BAC changed the cross-linking densities of the hydrogel dots, making them swell or shrink. Rheological measurements allowed for selecting hydrogels that withstand long-term shear forces present in microfluidic devices under continuous flow. Once implemented, the thiol-disulfide exchange allowed the hydrogel dots to successfully capture and release the protein bovine serum albumin (BSA). BSA was labeled with rhodamine B and functionalized with 2-(2-pyridyldithio)-ethylamine (PDA) to introduce disulfide bonds. The reversible capture and release of the protein reached an efficiency of 83.6% in release rate and could be repeated over 3 cycles within the microfluidic device. These results demonstrate that our redox-responsive hydrogel dots enable the dynamic capture and release of various different functionalized (macro)molecules (e.g., proteins and drugs) and have a great potential to be integrated into a lab-on-a-chip device for detection and/or delivery.

scholarly journals COMPOSITE OF CHITOSAN VANILIN / SULFONATED POLYSTYRENE AS POLYMER ELECTROLYTE MEMBRANES : CATIONIC EXCHANGE CAPACITY, SWELLING DEGREE AND THERMAL PROPERTIES

2016 ◽  
Vol 10 (2) ◽  
pp. 116
Author(s):  
Edi Pramono ◽  
Candra Purnawan ◽  
Yuniawan Hidayat ◽  
Jati Wulansari ◽  
Sayekti Wahyuningsih
Keyword(s):  
Thermal Properties ◽  
Composite Membranes ◽  
Exchange Capacity ◽  
Membrane Composition ◽  
Sulfonated Polystyrene ◽  
Swelling Degree ◽  
Electrolyte Membranes ◽  
Three Stages ◽  
Cationic Exchange

Research on the preparation and characterization of sulfonated polystyrene (PST) /chitosan vanillin (KV) composite as electrolyte membranes has been conducted in order to investigate the effect of PST and KV composition  to its chemical and physical properties. Polystyrene was modified by sulfonation reaction to produces PST<strong>, </strong>meanwhile chitosan was modified by schift base reaction to produces KV. The composite membranes were prepared by casting method and were characterized in order to identify the functional groups contained in the composite, the cation exchange capacity (CEC), the Swelling Degree (SD), the thermal properties and the morphology. The peak of imine vibration in the FTIR spectrum indicates that the chitosan vanilin was succesfully synthesized. Meanwhile, the peak of sulfonate vibration indicates the product of sulfonation on polystyrene. The result of CEC analysis shows that the addition of sulfonate groups on polystyrene and the addition of phenolic groups on chitosan increase the CEC value. The increasing of PST and KV concentration in membrane enhance the CEC value. However, the increasing of PST concentration in membrane composition even decrease the Swelling Degree of membranes. Meanwhile, the increasing of KV concentration increase the swelling degree of membranes. Thermal analysis shows that the thermal decomposition of membranes occurs in three stages i.e. the dehydration of water molecules, the degradation of the subtituen groups and the plasticizer and the degradation of the back bone of chitosan and polystyrene.

A Novel, Low-Cost C-C Composite Heat Sink Material

1996 ◽  
Vol 445 ◽  
Author(s):  
W. Kowbel ◽  
V. Chellappa ◽  
J.C. Withers
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Low Cost ◽  
Mechanical And Thermal Properties ◽  
New Class ◽  
Dielectric Coatings ◽  
Potential Applications ◽  
New Material ◽  
New Type ◽  
Composite Heat

AbstractRapid advances in high power electronics packaging require the development of new heat sink materials. Advanced composites designed to provide thermal expansion control as well as improved thermal conductivity have the potential to provide benefits in the removal of excess heat from electronic devices. Carbon-carbon (C-C) composits are under consideration for several military and space electronic applications including SEM-E electronic boxes. The high cost of C-C composits has greatly hindered their wide spread commercialization. A new manufacturing process has been developed to produce high thermal conductivity (over 400 W/mK) C-C composites at greatly reduced cost (less than $50/lb). This new material has potential applications as both a heat sink and a substrate. Dielectric coatings such as A1N and diamond were applied to this new type of heat sink material. Processing, as well as mechanical and thermal properties of this new class of heat sink material will be presented.

scholarly journals Polymer Electrolyte Membranes Based on Nafion and a Superacidic Inorganic Additive for Fuel Cell Applications

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 914 ◽  
Author(s):  
Lucia Mazzapioda ◽  
Stefania Panero ◽  
Maria Assunta Navarra
Keyword(s):  
Fuel Cell ◽  
Ion Exchange ◽  
Proton Exchange Membrane ◽  
Sol Gel ◽  
Composite Membranes ◽  
Exchange Capacity ◽  
Proton Exchange ◽  
Thermal Transitions ◽  
Ion Exchange Capacity ◽  
Electrolyte Membranes

Nafion composite membranes, containing different amounts of mesoporous sulfated titanium oxide (TiO2-SO4) were prepared by solvent-casting and tested in proton exchange membrane fuel cells (PEMFCs), operating at very low humidification levels. The TiO2-SO4 additive was originally synthesized by a sol-gel method and characterized through x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and ion exchange capacity (IEC). Peculiar properties of the composite membranes, such as the thermal transitions and ion exchange capacity, were investigated and here discussed. When used as an electrolyte in the fuel cell, the composite membrane guaranteed an improvement with respect to bare Nafion systems at 30% relative humidity and 110 °C, exhibiting higher power and current densities.

Biocompatibility Evaluation of Cellulose Nanowhisker from Bamboo Fibers for Potential Applications of Drug Delivery In Vitro

2014 ◽  
Vol 787 ◽  
pp. 468-473
Author(s):  
Yong Zhang ◽  
Lan Ma ◽  
Ye Li Yu ◽  
Ju Ming Yao
Keyword(s):  
Drug Delivery ◽  
Sulfuric Acid ◽  
Acid Hydrolysis ◽  
Oral Drug ◽  
Cytotoxicity Test ◽  
Cellulose Nanowhisker ◽  
Potential Applications ◽  
Bamboo Fibers ◽  
Cellulase Hydrolysis

The biocompatibility of the cellulose nanowhisker (CNW) from cellulase hydrolysis was evaluated in vitro for potential applications in drug delivery system. The assessments were comprised of cytotoxicity analysis and proliferation of human osteosarcoma MG-63 cells that were cultured with the resultant CNW. Some morphological and physico-chemical characteristics of the CNW were investigated. The cellulase hydrolysis conditions were optimized at a cellulase dosage of 0.01 mL/g dried fibers, a hydrolysis temperature of 60 °C, hydrolysis time of 3 h and bamboo fiber concentration of 2 wt%. Under these conditions, the as-prepared CNW retained more properties similar to the original bamboo fibers than those fabricated by sulfuric acid hydrolysis. Indirect cytotoxicity test of the CNW revealed it non-toxicity to the cells. The proliferation of the MG-63 cells with the CNW from cellulase hydrolysis was better than that from sulfuric acid hydrolysis. These results together with the fact that the cellulose hydrolysis preparation of CNW is simple and inexpensive make it a good candidate for the design of oral drug delivery device.

Chitosan Polyelectrolyte Complexes for Use in Tissue Engineering and Drug Delivery

2007 ◽  
Vol 539-543 ◽  
pp. 577-582
Author(s):  
Silvia Bubeníková ◽  
Igor Lacík ◽  
Dušan Bakoš ◽  
Lucia Vodná
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Reaction Time ◽  
Drug Delivery Systems ◽  
Chondroitin Sulphate ◽  
Delivery Systems ◽  
Medical Field ◽  
Polyelectrolyte Complexes ◽  
Potential Applications ◽  
Cross Linker

The paper presents the first part of the work focused on preparation of biodegradable chitosan microcapsules with tailored properties for potential applications in medical field as drug temporary carriers. In this paper, we aimed to prepare chitosan and chondroitin sulphate microcapsules using TPP as the second cross-linker and investigate the formation of the capsule membrane and its permeability in dependence on conditions of polyionic complexation. As a model, TPP was used to assess an influence of concentration and reaction time on the microcapsule formation. The method of inverse SEC was used for pores size and permeability limit of capsules assessment. For chitosan/CHS/TPP capsules, the distribution of pores size in the membrane is rather broad, which can be suitable for applications in tissue engineering and drug delivery systems.

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