Herein, we report the production of ionic polymer-metal composites (IPMCs) hybridized with cellulose nanofibrils (CNF) as a partial substitute for Nafion®. The aim is not only to reduce the production cost and enhance respective mechanical/thermal properties but also to bestow a considerable degree of biodegradability to such products. Formulations with di erent CNF/Nafion®
ratios were produced in a thin-film casting process. Crack-free films were air-dried and plated by platinum (Pt) through an oxidation-reduction reaction. The produced hybrids were analyzed in terms of thermal stability, mechanical and morphological aspects to examine their performance compared to the Nafion-based IPMC prior to plating process. Results indicated that films with higher CNF loadings had improved tensile strengths and elastic moduli but reduced ductility. Thermogravimetric analysis (TGA) showed that the incorporation of CNF to the matrix reduced its thermal stability almost linearly, however, the onset of decomposition point remained above 120 C, which was far above the
temperature the composite membrane is expected to be exposed to. The addition of a cross-linking agent to the formulations helped with maintaining the integrity of the membranes during the plating process, thereby improving surface conductivity. The focus of the current study was on the physical
and morphological properties of the films, and the presented data advocate the potential utilization of CNF as a nontoxic and sustainable bio-polymer for blending with perfluorosulfonic acid-based co-polymers, such as Nafion®, to be used in electroactive membranes.
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Eco-Friendly Cellulose Nanofiber Extraction from Sugarcane Bagasse and Film Fabrication
The development of cost-effective cellulose fibers by utilizing agricultural residues have been attracted by the scientific community in the past few years; however, a facile production route along with minimal processing steps and a significant reduction in harsh chemical use is still lacking. Here, we report a straightforward ultrasound-assisted method to extract cellulose nanofiber (CNF) from fibrous waste sugarcane bagasse. X-ray diffraction-based crystallinity calculation showed 25% increase in the crystallinity of the extracted CNF (61.1%) as compared to raw sugarcane bagasse (35.1%), which is coherent with Raman studies. Field emission scanning electron microscopy (FE-SEM) images revealed thread-like CNF structures. Furthermore, we prepared thin films of the CNF using hot press and solution casting method and compared their mechanical properties. Our experiments demonstrated that hot press is a more effective way to produce high strength CNF films; Young’s modulus of the thin films prepared from the hot press was ten times higher than the solution casting method. Our results suggest that a combination of ultrasound-based extraction and hot press-based film preparation is an efficient route of producing high strength CNF films.
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- Award ID(s):
- 1735971
- NSF-PAR ID:
- 10255453
- Date Published:
- Journal Name:
- Sustainability
- Volume:
- 12
- Issue:
- 15
- ISSN:
- 2071-1050
- Page Range / eLocation ID:
- 6015
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The inferior water vapor permeability and water resistance properties are the major challenges that hindered the development of chitosan‐CNF composites for packaging applications. In this study, the chitosan‐CNF composite films were prepared with in situ crosslinking of citric acid (CA) to reduce the percent water uptake (WU) and water vapor permeability (WVP). The composite films were produced by the solvent casting method with 10%, 15%, and 20% CNF as a reinforcement, 20%, 25%, and 30% CA as a crosslinker, and 20% glycerol as a plasticizer. The Fourier transform infrared (FTIR) spectra of composite films with a peak at 1710 cm−1confirmed the effective crosslinking of citric acid on the chitosan‐CNF matrix. The crosslinked composite films exhibited the lowest WU of 39% and WVP of 9.99 × 10−7g/Pa s m2with reduced light transmittance due to CNF reinforcement. The scanning electron microscopy (SEM) study showed the smooth surface morphology of composite films. The CA crosslinking slightly decreased the tensile strength of composite films. However, the composite film with optimal CNF and CA concentration (25% and 20%, respectively) exhibited comparable tensile strength with other synthetic and biopolymer composites and can be used as a potential biopolymer composite for packaging applications.
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The multiscale morphology and device performance of printed semiconducting polymers are highly sensitive to the substrate/ink interfacial properties during solution coating. There is an urgent need for general design rules correlating the substrate properties and conjugated polymer (CP) morphology, which do not yet exist. Dynamic surfaces are particularly promising for templating highly crystalline and highly aligned conjugated polymer thin films and have been shown in recent studies. Herein, we implement the dynamic-templating method using a series of liquid-infused nanoporous substrates as a tool to study the impact of template reconfigurability and chemistry on the multiscale morphology of conjugated polymer thin films, using a high performing donor–acceptor polymer (DPP-BTz) as a model compound. By quantifying the enthalpy of adsorption, we demonstrate that the strength of template–CP interactions directly measures the effectiveness of dynamic surfaces in promoting conjugated polymer crystallization and alignment. We further show that the enthalpy of interactions increases by enhancing the template dynamics and is sensitively modulated by template chemistry. Specifically, increasing the template–CP interactions leads to a larger domain size and higher degree of crystallinity in templated conjugated polymer thin films prepared by meniscus-guided solution coating. This observation validates our hypothesis that dynamic templates function by promoting the nucleation of conjugated polymers. We also demonstrate that such dynamic-template-dependent morphology is independent of coating speed. Notably, the enhanced morphological properties modulate the charge carrier mobility in field-effect transistors (FETs) over an order of magnitude reaching a hole mobility of 2.8 cm 2 V −1 s −1 . This work is a significant step towards establishing general guidelines on how the substrate–ink interfacial properties influence morphology and performance of solution coated CP thin films.more » « less
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Biocomposites have become more mainstream over the past decades for preserving the environment and producing sustainable materials as a potential substitute to synthetic polymer based composites derived from scarce petroleum materials. However, it is essential to investigate their mechanical, thermal and fire retardancy performance to answer the question of their suitability in automobile, biomedical, construction, film packaging, and commercial industries. In this work, we have studied one such promising biocomposites, jute fiber/poly (3-hydroxy-butyrate-co-3-valerate) (PHBV) and investigated their aforementioned properties. At first, 3–15 wt% halloysite nanotubes (HNTs) were dispersed in PHBV/chloroform mixture using an ultrasound process. PHBV/HNTs thin films were then prepared using the solvent casting method. Finally, jute fiber/PHBV-HNTs bionanocomposites were prepared using the compression mold method. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were performed to study the thermal and fire retardancy properties. Uniaxial tensile and flexure tests were also performed to investigate the mechanical properties. In addition, scanning electron microscopy (SEM) was carried out to analyze the fracture surfaces of flexure tested samples. Results of jute/PHBV composites showed a significant increase in thermal and mechanical properties at 5 wt% HNTs loading in comparison to neat composites (without HNTs). In contrast, the composites with 15 wt% loading showed superior fire retardancy. SEM images of flexure tested samples showed enhanced interfacial bonding and less fiber pullout when compared to neat counterparts.
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/su12156015
