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Growing demand for animal products caused by a growing population and improved living-standards also yields large quantities of manure constituting an eminent problem. Herbivore manure can be utilized as fertilizer or for biogas production, which, however, disregards the full potential of manure as feedstock for lignocellulosics. Thus, an integrated process combining biogas production and isolation of natural fibres next to providing fertilizer precursors would constitute a major leap forward.

Funding Information: The authors acknowledge Tiergarten Schönbrunn for providing the elephant manure, Johannes Theiner from the Microanalytical Laboratory (Faculty of Chemistry) at the University of Vienna for performing elemental analysis and IR-spectroscopy, and the following students for their help with various aspects of the work: Alexander Blocher, Lisa Panzenböck, Hanna Hirn, Nina Troppmaier, Manuel Holzman (all University of Vienna), and Elodie Schaffner (Institut National Polytechnique de Toulouse). The authors also thank Stephan Puchegger from the Faculty Center for Nano Structure Research for his help with the SEM and Antje Potthast (Institute of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna) for measuring the molecular weight of the cellulose. This work was supported by OeAD (WTZ ZA 03/2017) enabling the collaboration with CSIR, Port Elisabeth, South Africa. K.W. is grateful for the financial support provided by the Institute of Materials Chemistry of University of Vienna (371300). E.K. acknowledges the support by FinnCERES Materials Bioeconomy Ecosystem. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. The demand for animal products has significantly increased over the past decades as a result of the growing population and the heightened standards of living. Increased livestock farming does not only yield desired products but also significant quantities of wastes, particularly manure whose storage and application are being monitored with a tightening network of regulations. The problem is that manure is considered merely as a substrate for biogas production or as a fertilizer, whereas the substantial portion of fibers residing in herbivore manure has remained underutilized. Here, we propose a manure management system, in which not only biogas and fertilizer precursors but also high-value materials in the form of (nano)cellulose are produced. We show that high biogas yields can be achieved for elephant manure and the remaining substrate enables effortless isolation of cellulose nanofibers, leading to a significant reduction of the environmental impact compared with traditional systems based on wood.

Hydrophobically modified associating polymers could be effective drag-reducing agents containing weak "links" which after degradation can reform, protecting the polymer backbone from fast scission. Previous studies using hydrophobically modified polymers in drag reduction applications used polymers with

We evaluated the influence of blending various renewable polymer grades and amounts to allow for high stretchability during stretching at 800 mm/s to produce polymer tapes with high Young’s moduli E and yield stress σy similar to industrial production of non-degradable synthetic polymers. Renewable polymer blends based on TPS, PBAT, and PLA with high stretchability as well as high E and σy of stretched tapes comparable to high-density polyethylene (PE-HD) and isotactic polypropylene were identified. High stretchability (up to 380%) was facilitated with TPS-PBAT tapes and comparably high E (up to 5000 MPa) and σy (up to 160 MPa) of stretched tapes were obtained for mixtures of different PLA grades resulting in E-moduli exceeding that of PE-HD. A balance of these properties approaching those of synthetic polymers was achieved with PLA-PBAT blends (stretchability: 340%, E: 4500 MPa, σy: 120 MPa).

The use of chemical and energy intensive delignification processes in industrial pulping generates cellulosic fibres that are hydrophilic, hygroscopic and functionally restricted to paper and cardboard applications. Here, we propose a bio-based alternative to chemical pulping utilising herbivores to harvest and grind lignocellulosic materials followed by natural fungal growth to delignify and hybridise them to generate hierarchical composite papers with altered, water-repelling surface properties. These papers comprise cellulose and fungal biopolymers produced by cultivation of T. versicolor and P. ostreatus on elephant manure. Papers with considerably more hydrophobic surfaces were obtained at glucosamine contents as low as 0.1 wt%. Paper tensile strengths and elastic moduli were improved with longer fungal growth periods, spanning several weeks, resulting in comprehensive interfacing of cellulose microfibrils through tough nanoscale fungal chitin-β-glucan networks within the papers. Papers produced from lignocellulosic material colonised with P. ostreatus for 16 weeks exhibited the highest tensile strengths and more hydrophobic surfaces than T. versicolor. Hybridisation of lignocellulose with fungal biopolymers resulting in improved surface and mechanical properties highlights the extended opportunities of fungal delignification bioprocessing and demonstrates the considerable potential of the fungal biorefinery as an economical, and as of yet underexploited technology.

Fungi-derived leather substitutes are an emerging class of ethically and environmentally responsible fabrics that are increasingly meeting consumer aesthetic and functional expectations and winning favour as an alternative to bovine and synthetic leathers. While traditional leather and its alternatives are sourced from animals and synthetic polymers, these renewable sustainable leather substitutes are obtained through the upcycling of low-cost agricultural and forestry by-products into chitinous polymers and other polysaccharides using a natural and carbon-neutral biological fungal growth process. Following physical and chemical treatment, these sheets of fungal biomass visually resemble leather and exhibit comparable material and tactile properties. Fungi-derived material can substitute for leather. This Review synthesizes information on this process and its environmental and ethical benefits.

The long-term drag reduction capability of poly(ethylene oxide) with a nominal molar weight of [Formula: see text] g/mol dissolved in water was investigated in a pilot-scale pipe flow device (inner diameter of test section 26 mm) at a Reynolds number of 105. A total loss of the initially high (75%) drag reduction capability was observed over a flow distance of several ∼10 km while the molar weight of the polymer was still [Formula: see text] g/mol. Mechanical degradation in the turbulent flow as well as ageing of the polymer dissolved in water caused this loss in drag reduction capability. A simple ansatz of two independent, statistical polymer chain scission mechanisms was used to describe the polymer degradation empirically using a modified Brostow model. This empirical description was applied successfully and suggested that the polymer exhibited at least 15 cleavage points for mechanical degradation.

The abstract is available here: https://uscholar.univie.ac.at/o:1633047

Due to its unique properties, nano fibrillated cellulose (NFC) has been a popular topic of research in recent years. Nevertheless, literature assessing environmental impacts of NFC production is scarce, especially for using other starting materials than wood pulp. Hence, in this study, a new approach of cascaded use of manure to produce biogas and subsequently use the cellulose containing digestate for NFC production (manure scenario) is compared to the production from Kraft pulp from hardwood chips (wood chips scenario) via life cycle assessment (LCA). To produce comparable outputs (NFC and biogas) in both scenarios a typical Austrian biogas plant with maize silage and pig slurry as input material is included in the wood chips scenario. A proxy approach is used to upscale the manure scenario from laboratory to an industrial scale (except for the pulp to NFC step) to ensure comparability of both scenarios. The impact categories global warming potential (GWP), fossil resource scarcity, freshwater eutrophication, human toxicity, terrestrial acidification (TAP) and terrestrial ecotoxicity potential are analysed referring to the functional unit of 1 kg NFC. Results show that the manure scenario has at least 45% lower impacts in all assessed categories. GWP is 4.41 kg CO

The abstract is available here: https://uscholar.univie.ac.at/o:1641772

Greener alternatives to synthetic polymers are constantly being investigated and sought after. Chitin is a natural polysaccharide that gives structural support to crustacean shells, insect exoskeletons, and fungal cell walls. Like cellulose, chitin resides in nanosized structural elements that can be isolated as nanofibers and nanocrystals by various top-down approaches, targeted at disintegrating the native construct. Chitin has, however, been largely overshadowed by cellulose when discussing the materials aspects of the nanosized components. This Perspective presents a thorough overview of chitin-related materials research with an analytical focus on nanocomposites and nanopapers. The red line running through the text emphasizes the use of fungal chitin that represents several advantages over the more popular crustacean sources, particularly in terms of nanofiber isolation from the native matrix. In addition, many β-glucans are preserved in chitin upon its isolation from the fungal matrix, enabling new horizons for various engineering solutions.

The influence of the crystallization temperature and the pressure on the crystallization kinetics, structure and compression strength of γ-polypropylene was investigated. Samples were produced in a custom-made high-pressure crystallization cell and characterized by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). It could be shown that the strength is mainly affected by the mean lamellar thickness. The strength of γ-PP is at least 40% higher than α-PP at the same mean lamellar thickness. This confirms the hypothesis that the arrangement of non-parallel chains restricts the number of possible slip systems so that almost no mobile dislocations are generated. The mode of nucleation is only slightly affected by the crystallization pressure. The Avrami coefficient is n = 2.5 ± 0.1 at the beginning of crystallization and largely independent of pressure.

Contamination of fresh water sources with heavy metal ions constitutes a serious threat to drinking water safety. Treatment of water in order to remove these contaminants, e.g. copper ions, is thus an important task, usually performed by utilizing adsorbents or continuous membrane/filter processes. In particular combinations of these processes, i.e. adsorption or ion-exchange membranes/filters, are potential solutions in this regard. Thereby, materials derived from renewable resources constitute an environmentally benign alternative to traditional adsorption membrane/filter materials. For example, anionic TEMPO-oxidized cellulose nanofibrils (TCNF) were demonstrated to have high affinity towards heavy metal ions but nanopaper membranes made thereof suffer from low permeance and hence limited performance. To achieve high permeance and efficient adsorption of metal ions utilizing pure nanopapers has still not been possible. However, decorating a porous natural fibre substrate with TCNF should allow for high adsorption capacity towards Cu2+ together with high water permeance. We here present natural fibre-nanocellulose composite filters derived from flax and agave fibres, extracted e.g. from tequila residues, decorated with TCNF. The performance of these filters was determined with respect to their permeance and adsorption capacity for copper. It was shown that this new type of filter derived from industrial crop residues is capable of adsorbing high amounts of Cu(II) ions during a continuous filtration process with very high permeances enabled by their highly porous nature.

Agricultural by-products can be upcycled into environmentally-sustainable, inexpensive chitinous materials and nanofibers derived from fungal mycelium for composites, cosmetics, pharmaceuticals and water treatment applications. This study determined the suitability of common agricultural by-products as medium for fungal growth. Growth was measured by quantifying ergosterol, a unique fungal product, in solid and liquid media. The results reveal that fungi grew less on rice hull, sugarcane bagasse and wheat straw agricultural by-products than on commercial wheat grains. However, the liquid agricultural by-product blackstrap molasses facilitated very high biomass production, outperforming the commonly used laboratory nutrient malt extract. Hyphal fusion, sheet formation and hyphal diameter metrics of fungi growing on each substrate were evaluated by SEM to assess suitability for chitin nanofiber production. Utilising these materials offers a cheap, renewable, easily-isolated, and abundant alternative to problematic crustacean chitin that when implemented on a large scale could rapidly upcycle low-value agricultural by-products into high-value chitinous materials.

Polyimides (PI) generally have a high affinity for single-walled carbon nanotubes (SWNTs), but they suffer from poor solubility in most low boiling point organic solvents and low compatibility with common resins (such as epoxy) used in composites, limiting their suitability as dispersants. PI block copolymer systems containing reactive poly(ester carbonate)s have not yet been reported and are expected to act as effective reactive dispersing agents of SWNTs. Herein, PI-derived block copolymers are synthesized via ring-opening copolymerization of lactide (LA) (a control monomer) and allyl-bearing 2-methyl-2-(allyloxycarbonyl)-propylene carbonate (MAC) from the OH-terminal ends of the PI block to produce PLA-PI-PLA (TB1, a control) and PMAC-PI-PMAC (TB2). The allyl pendant group of TB2 allows further facile functionalization to form a third series of epoxidized (EP) derivatives, i.e. PMACEP-block-PI-block-PMACEP (TB3). TB3 copolymer when mixed with a conventional structural epoxy resin forms blends that do not show inferior tensile properties compared with the epoxy, which is unusual. Furthermore, the mixing solvent tetrahydrofuran (THF) can be readily evaporated off after forming the blends. TB3-dispersed (2 wt%) SWNTs added to epoxy increased the tensile strength, modulus, and elongation at break of the resulting nanocomposite films by 40%, 34%, and 26% respectively, compared to the baseline epoxy resin. Furthermore, when TB3b triblock-dispersed SWNTs in epoxy were combined with fuzzy carbon fibers, i.e. carbon nanotube-grafted-carbon fibers (CNT-g-CF), a synergistic interfacial strength reinforcement was observed, together with shifting of the failure mode from the matrix interphase to the carbon fiber-grafted nanotube interface. The ultimate interfacial shear strength between the TB3-dispersed SWNT-epoxy matrix and the fuzzy carbon fibers (i.e., fibers having carbon nanotubes grown on them) measured via single fiber pull-out tests was 100 MPa, which was ca. 11% improvement over the baseline unsized carbon fiber in neat epoxy. To our knowledge, this is the first evidence of a synergistic enhancement in interfacial properties when fuzzy carbon fibers are combined with a SWNT-reinforced epoxy using the new epoxidized TB3 nanotube dispersing agent that forms a strong covalent TB3–epoxy interface. The new functionalizable TB3 synthesis route introduced here is generalizable to other PI-based copolymers with diverse functionalities and solvent compatibilities. ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) NMRC (Natl Medical Research Council, S’pore) MOH (Min. of Health, S’pore) Accepted version

3D Printing, utilizing a layer-by-layer deposition of materials, is advantageous to manufacture parts as it involves fewer process steps, provides great flexibility for prototyping, especially of complex parts, and has low material waste. Yet, the mechanical properties of 3D printed parts have always been a concern due to the weak inter-layer bonding and rough surface. 3D printed continuous fiber reinforced polymer composites (CFRPCs) use continuous fiber reinforcements for the polymer matrix, which significantly improve the mechanical properties of printed parts. CFRPCs are widely used in aerospace, automobile, medical industry and other fields due to their excellent specific mechanical properties. Compared with other 3D printing technologies, fused deposition modeling (FDM) has the advantages of low cost and simple operation to fabricate CFRPCs. In this review article, the choices of various continuous fibers and matrix polymers and their effect on the performance of CFRPCs have been discussed. Furthermore, the latest equipment and methods to fabricate CFRPCs will be summarized, and the key parameters affecting the properties of CFRPCs analyzed. At the end, based on the related research, we critically highlight the challenges and opportunities associated with FDM of CFRPCs to point out the direction of future work.

Polyetheretherketone (PEEK) is a high-performance semi-crystalline thermoplastic polymer with outstanding mechanical properties, high thermal stability, resistance to most common solvents, and good biocompatibility. A high temperature thermally induced phase separation technique was used to produce PEEK foams with controlled foam density from PEEK in 4-phenylphenol (4PPH) solutions. Physical and mechanical properties, foam and bulk density, surface area, and pore morphology of foamed PEEK were characterized and the role of PEEK concentration and cooling rate was investigated. Porous PEEK with densities ranging from 110 to 360 kg/m

A series of carbon black filled polyHIPEs was synthesised following a new preparation protocol. 1 wt% carbon black was dispersed in the monomer mixture. In order to enhance the stability of the suspension, in situ polymer grafting of carbon black was performed by initiating the polymerisation prior to emulsifying the formulation. All of the carbon black filled polymer foams synthesised via the new preparation protocol have the characteristics usually observed for polyHIPEs. Carbon black particles are incorporated into the pore walls without affecting the pore structure of the polyHIPEs. The new preparation protocol positively influenced the properties of the resulting polyHIPEs namely the pore interconnectivity is increased and a water permeability of up to 2.3 D is achieved.

High internal phase emulsions (HIPEs) are indisputably a core technology for various industries involving pharmaceuticals, food, cosmetics, and biologics but they usually require surfactants/co-surfactants to form, which is often undesired. More specifically, micro-HIPEs are thermodynamically stable, optically clear emulsions with droplet sizes in the range of around 1–100 nm that form spontaneously with little energy input but are rare. Mini-/macro-HIPEs have larger droplet sizes in the range of 50–500 nm and >500 nm, respectively, and typically require high energy input for emulsification. We have synthesized a series of chitosan-graft-oligoN-isopropylacrylamide-graft-oligolysine (CSNLYS) copolymers that act as both emulsifiers for HIPEs without needing extraneous surfactants as well as the matrix material of the resulting porous solid polyHIPE. By merely adjusting the length of the oligolysine graft from relatively long to medium to short, we can form either a micro-, mini- or macro-HIPE, respectively. These emulsions can then be solidified into porous polymers, polyHIPEs, simply by increasing the temperature by exploiting the copolymer thermo-responsiveness and then removing the solvents. These porous polyHIPE, particularly the ones from micro-HIPEs, have surface areas as high as 988 m2 g−1 and pore sizes below 200 nm.

By whipping air into a solution containing the pulp processing by-product black liquor, crosslinker and surfactant, stable air-in-black liquor froths were produced. The air volume in the froths was controlled by tuning the viscosity of the black liquor and the whipping time. By the selectively crosslinking the renewable lignin and hemicellulose content in the black liquor froths, lignin foams possessing a porosity of up to 88% have been produced. The porosity, pore and pore throat sizes decreased with increasing viscosity of the continuous liquid phase of the black liquor froths. The resulting lignin foams were pyrolysed to produce renewable carbon foams, which retained the shape and macropore structure of the lignin foam precursor well, opening the door to structurally designable carbon foams from lignin. The work demonstrated that froth templating using an industrial by-product is a viable low-cost method to produce both stable lignin and carbon foams.

Novel structural supercapacitors have been fabricated which can simultaneously carry mechanical loads as well as store electrochemical energy. Structural supercapacitors are fabricated by impregnating activated carbon fibre mat electrodes and glass fibre mat separator with crosslinked polymer electrolytes using the resin infusion under flexible tooling method. Mesoporous silica particles are also used as reinforcements to further improve the electrochemical and mechanical performance of structural supercapacitors. The fabricated structural supercapacitors have been characterised through chronoamperometry method and impedance spectroscopy to evaluate the electrochemical performance and in-plane shear properties to evaluate the mechanical performance. A multifunctional structural supercapacitor, exhibiting simultaneously a power density of 34 W kg−1, an energy density of 0.12 Wh kg−1 and a shear modulus of 1.75 GPa, has been fabricated.

The fiber–matrix interface plays a critical role in determining composite mechanical properties. While a strong interface tends to provide high strength, a weak interface enables extensive debonding, leading to a high degree of energy absorption. Balancing these conflicting requirements by engineering composite interfaces to improve strength and toughness simultaneously still remains a great challenge. Here, a nanostructured fiber coating was realized to manifest the critical characteristics of natural nacre, at a reduced length scale, consistent with the surface curvature of fibers. The new interphase contains a high proportion (∼90 wt %) of well-aligned inorganic platelets embedded in a polymer; the window of suitable platelet dimensions is very narrow, with an optimized platelet width and thickness of about 130 and 13 nm, respectively. An anisotropic, nanostructured coating was uniformly and conformally deposited onto a large number of 9 μm diameter glass fibers, simultaneously, using self-limiting layer-by-layer assembly (LbL); this parallel approach demonstrates a promising strategy to exploit LbL methods at scale. The resulting nanocomposite interphase, primarily loaded in shear, provides new mechanisms for stress dissipation and plastic deformation. The energy released by fiber breakage in tension appear to spread and dissipate within the nanostructured interphase, accompanied by stable fiber slippage, while the interfacial strength was improved up to 30%.

We realised spring/spacer elements, which are crucial components of capacitive energy harvesters, by syringe printing of polyurethane diacrylate and ethylhexyl acrylate based high (HIPE) and medium (MIPE) internal phase emulsion templates followed by UV polymerisation. The resulting micropatterned poly(merised)H/MIPEs are very flexible and reversibly compressible to a strain of 50% as cyclic compression test revealed. Dynamic mechanical analysis has shown constant mechanical behaviour of the macroporous polymer springs under a loading/unloading at a frequent of 2 Hz for 10 h, proving the practical durability of the springs. Within a prototype harvester the micropatterned macroporous springs allowed to compartmentalise Hg droplets and provided the required restoring force to operate the device successfully; the capacitive change of the device within one compression-recovery cycle reached 570 pF.

Trials have been conducted to investigate the shape memory capability of an interleaved composite consisting of carbon fibre reinforced epoxy laminae and polystyrene interleaf layers. It has been shown that the composite can be readily re-shaped by deforming it at an elevated temperature and then cooling the composite in the deformed state. On re-heating, the composite almost fully returns to its original shape. One potential application of the shape memory capability of the interleaved composite is in deployable structures and a simple structure has been manufactured to demonstrate this possibility.

Supported hydrogel membranes were produced by one-pot synthesis by polymerisation of suitable emulsion templates. High internal phase emulsions (HIPEs) with styrene (St), divinylbenzene (DVB) and ethylhexyl acrylate (EHA) in the continuous phase and methacrylic acid (MAA) in the internal phase were polymerised to prepare poly(MAA) hydrogel grafted poly(St- co -DVB- co -EHA) poly(merised)HIPEs. By changing the concentration of the crosslinker, N , N′ -methylenebisacrylamide, in the internal phase of the emulsion template the crosslinking density of the grafted poly(MAA) was tuned. The presence of the hydrogel was indicated by a change in pore morphology, e.g. coverage of the pore throats and the wrinkled pore wall surface, and the increase in the density of the composite polyHIPEs as compared to control polyHIPEs. Moreover, the increase in foam density and reduction of porosity were related to the crosslinking degree of the hydrogel. The water uptake of the composite polyHIPEs exceeded the pore volume of the polyHIPE scaffold supporting the grafted hydrogel. The permeability and rejection of aqueous solutions of polyethylene glycol (PEG) by the hydrogel grafted polyHIPE membranes were strongly pH dependent, the permeability decreased and the rejection of PEG increased with increasing pH due to the increased swelling of the hydrogel. A 91% rejection of 50 kDa PEG for polyHIPE supported hydrogel membranes has been identified, which qualifies such membranes for ultrafiltration applications.

Nitrates constitute a severe problem for the quality of potable water. The removal of nitrates from water can be performed utilizing continuouslyoperating cellulose nanopaper ion-exchangers, which so far are unfortunately of only moderate efficiency. Here we demonstrate cationic cellulosenanopapers comprising cellulose nanofibrils carrying a high amount of ammonium groups (1.6 g mmol−1, i.e. 0.62 mmol g−1), which areanticipated to enable efficient removal of nitrate ions from aqueous solutions. Thin nanopapers were shown to have high adsorption capacities.Therefore we prepared low grammage nanopapers using a papermaking process from cellulose nanofibrils prepared from paper mill sludge. Theperformance of these cationic nanopapers was characterized by their permeance, with these new cationic nanopapers having a permeance of morethan 100 L m−2 h−1 MPa−1, which is far greater than the permeance of conventional nanopapers. Furthermore, nitrate ions were successfullyremoved from water by capturing them through adsorption onto the cationic nanopaper by primarily an ion-exchange mechanism. These cationicnanopapers possessed adsorption capacities of almost 300 mg g−1, which is superior to commonly used nanopaper ion-exchangers and batch-wiseapplied adsorbents. Utilization of an industrial side-stream in combination with very good membrane performance demonstrates the use ofresource efficient technologies in an important sector.

The HTI cellulose triacetate (CTA) and novel thin film composite (TFC) membranes are used to study the multifaceted interactions involved in the fouling and cleaning of forward osmosis (FO) membranes, using calcium alginate as a model foulant. Results show that fouling on the TFC membrane was more significant compared to CTA, arising from a variety of factors associated with surface chemistry, membrane morphology and structural properties. Interestingly, it was observed that in FO mode, membrane surface properties dominated over fouling layer properties in determining fouling behaviour, with some surface properties (e.g. surface roughness) having a greater effect on fouling than others (e.g. surface hydrophilicity). In pressure retarded osmosis (PRO) mode, structural properties of the support played a more dominant role whereby fouling mechanism was specific to the foulant size and aggregation as well as the support pore size relative to the foulant. Whilst pore clogging was observed in the TFC membrane due to its highly asymmetric and porous support structure, fouling occurred as a surface phenomenon on the CTA membrane support layer. Besides pore clogging, the severe fouling observed on the TFC membrane in PRO mode was due to a high specific mass of foulant adsorbed in its porous support. It was observed that a trade-off between enhanced membrane performance and fouling mitigation is apparent in these membranes, with both membranes providing improvement in one aspect at the expense of the other. Hence, significant developments in their surface and structural properties are needed to achieve high anti-fouling properties without compromising flux performance. Measured fouling densities on the studied surfaces suggest that there is not a strong correlation between foulant-membrane interaction and fouling density. Cleaning results suggest that physical cleaning was more efficient on the CTA membrane compared to the TFC membrane. Further, they implied that despite different mechanisms of fouling and quantities of foulant adsorbed in FO membranes, FO is a resilient process with high cleaning efficiencies and fouling reversibility.

The structural component of fungal cell walls comprises of chitin covalently bonded to glucan; this constitutes a native composite material (chitin-glucan, CG) combining the strength of chitin and the toughness of glucan. It has a native nano-fibrous structure in contrast to nanocellulose, for which further nanofibrillation is required. Nanopapers can be manufactured from fungal chitin nanofibrils (FChNFs). FChNF nanopapers are potentially applicable in packaging films, composites, or membranes for water treatment due to their distinct surface properties inherited from the composition of chitin and glucan. Here, chitin-glucan nanofibrils were extracted from common mushroom (Agaricus bisporus) cell walls utilizing a mild isolation procedure to preserve the native quality of the chitin-glucan complex. These extracts were readily disintegrated into nanofibre dimensions by a low-energy mechanical blending, thus making the extract dispersion directly suitable for nanopaper preparation using a simple vacuum filtration process. Chitin-glucan nanopaper morphology, mechanical, chemical, and surface properties were studied and compared to chitin nanopapers of crustacean (Cancer pagurus) origin. It was found that fungal extract nanopapers had distinct physico-chemical surface properties, being more hydrophobic than crustacean chitin.

Mycelium, the vegetative growth of filamentous fungi, has attracted increasing commercial and academic interest in recent years because of its ability to upcycle agricultural and industrial wastes into low-cost, sustainable composite materials. However, mycelium composites typically exhibit foam-like mechanical properties, primarily originating from their weak organic filler constituents. Fungal growth can be alternatively utilized as a low-cost method for on-demand generation of natural nanofibrils, such as chitin and chitosan, which can be grown and isolated from liquid wastes and byproducts in the form of fungal microfilaments. This study characterized polymer extracts and nanopapers produced from a common mushroom reference and various species of fungal mycelium grown on sugarcane byproduct molasses. Polymer yields of ∼10-26% were achieved, which are comparable to those of crustacean-derived chitin, and the nanopapers produced exhibited much higher tensile strengths than the existing mycelium materials, with values of up to ∼25 MPa (mycelium) and ∼98 MPa (mushroom), in addition to useful hydrophobic surface properties resulting from the presence of organic lipid residues in the nanopapers. HCl or H2O2 treatments were used to remove these impurities facilitating tuning of mechanical, thermal, and surface properties of the nanopapers produced. This potentially enables their use in a wide range of applications including coatings, membranes, packaging, and paper.

Carbon aerogel (CAG) is a potential hierarchical reinforcement to improve the matrix-dominated mechanical properties of continuous carbon fibre reinforced polymer (CFRP) composites in both multifunctional and purely structural applications. When using CAG to reinforce a polyethylene glycol diglycidyl ether (PEGDGE) matrix, the interlaminar shear strength, compressive modulus and strength increased approximately four-fold, whilst the out-of-plane electrical conductivity increased by 118%. These mechanical and electrical performance enhancements significantly improve the multifunctional efficiency of composite structural supercapacitors, which can offer weight savings in transport and other applications. However, CAG also has the potential to reinforce conventional continuous CF composites in purely structural contexts. Here, CAG reinforcement of structural epoxy resin composites marginally increased compressive (1.4%) and tensile (2.7%) moduli respectively, but considerably reduced compressive, tensile and interlaminar shear strengths. Fractographic analysis shows that the reduced performance can be attributed to poor interfacial adhesion; in the future, alternative processing routes may resolve these issues to achieve advances in both moduli and strengths over conventional structural CFRPs.

Membranes and filters are essential devices, both in the laboratory for separation of media, solvent recovery, organic solvent and water filtration purposes, and in industrial scale applications, such as the removal of industrial pollutants, e.g. heavy metal ions, from water. Due to their solvent stability, biologically sourced and renewable membrane or filter materials, such as cellulose or chitin, provide a low-cost, sustainable alternative to synthetic materials for organic solvent filtration and water treatment. Here, we investigated the potential of fungal chitin nanopapers derived from A. bisporus (common white-button mushrooms) as ultrafiltration membranes for organic solvents and aqueous solutions and hybrid chitin-cellulose microfibril papers as high permeance adsorptive filters. Fungal chitin constitutes a renewable, easily isolated, and abundant alternative to crustacean chitin. It can be fashioned into solvent stable nanopapers with pore sizes of 10−12 nm, as determined by molecular weight cut-off and rejection of gold nanoparticles, that exhibit high organic solvent permeance, making them a valuable material for organic solvent filtration applications. Addition of cellulose fibres to produce chitin-cellulose hybrid papers extended membrane functionality to water treatment applications, with considerable static and dynamic copper ion adsorption capacities and high permeances that outperformed other biologically derived membranes, while being simpler to produce, naturally porous, and not requiring crosslinking. The simple nanopaper production process coupled with the remarkable filtration properties of the papers for both organic solvent filtration and water treatment applications designates them an environmentally benign alternative to traditional membrane and filter materials.

Access to clean potable water is increasingly becoming a struggle for whole humankind, thus water treatment to remediate wastewater and fresh water sources is an important task. Pollutants in the nanoscale, such as viruses and macromolecules, are usually removed by means of membrane filtration processes, predominantly nanofiltration or ultrafiltration. Cellulose nanopapers, prepared from renewable resources and manufactured by papermaking, have recently been demonstrated to be versatile alternatives to polymer membranes in this domain. Unfortunately, so far nanopaper filters suffer from limited permeance and thus efficiency. We here present nanopapers made from bacterial cellulose dispersed in water or different types of low surface tension organic liquids (alcohol, ketone, ether) through a simple papermaking process. Nanopapers prepared from organic liquids (BC-org) exhibited 40 times higher permeance, caused by a lower paper density hence increased porosity, compared to conventional nanopapers produced from aqueous dispersions, ultimately enhancing the efficiency of bacterial cellulose nanopaper membranes. Despite their higher porosity, BC-org nanopapers still have pore sizes of 15-20 nm similar to BC nanopapers made from aqueous dispersions, thus enabling removal of contaminants the size of viruses by a size-exclusion mechanism at high permeance.

There is increasing focus on the development of bioactive scaffolds for tissue engineering and regenerative medicine that mimic the native nanofibrillar extracellular matrix. Solution blow spinning (SBS) is a rapid, simple technique that produces nanofibers with open fiber networks for enhanced cell infiltration. In this work, highly porous bioactive fibers were produced by combining SBS with thermally induced phase separation. Fibers composed of poly(d,l-lactide) (PLA) and dimethyl carbonate were sprayed directly into a cryogenic environment and subsequently lyophilized, rendering them highly porous. The surface areas of the porous fibers were an order of magnitude higher in comparison with smooth control fibers of the same diameter (43.5 m2·g–1 for porous fibers produced from 15% w/v PLA in dimethyl carbonate) and exhibited elongated surface pores. Macroporous scaffolds were produced by spraying water droplets simultaneously with fiber formation, creating a network of fibers and ice microspheres, which act as in situ macroporosifiers. Subsequent lyophilization resulted in three-dimensional (3D) scaffolds formed of porous nanofibers with interconnected macropores due to the presence of the ice spheres. Nanobioactive glass was incorporated for the production of 3D macroporous, bioactive, therapeutic-ion-releasing scaffolds with potential applications in non-load-bearing bone tissue engineering. The bioactive characteristics of the fibers were assessed in vitro through immersion in simulated body fluid. The release of soluble silica ions was faster for the porous fibers within the first 24 h, with confirmation of hydroxyapatite on the fiber surface within 84 h.

Polymerised high internal phase emulsions (polyHIPEs) have drawn extensive interest in recent years; however, industrial applications do require polyHIPEs to be tough and robust. The mechanical properties of polyHIPEs can be tuned by copolymerisation of polyurethane diacrylate (PUDA) and styrene. The resulting open-porous poly(styrene-co-PUDA)HIPEs were much less brittle and friable when compared to conventional poly(styrene-co-divinylbenzene)HIPEs. Moreover, poly(styrene-co-PUDA)HIPEs have impact strengths up to 10 times higher than poly(styrene-co-divinylbenzene)HIPEs. The styrene/PUDA ratio determines the morphology, thermal and mechanical properties of the poly(styrene-co-PUDA) macroporous polymers. The viscous PUDA promotes the formation of small pores in polyHIPEs. A high PUDA content of the copolymer results in a dual glass transition temperature and low mechanical properties. By using an optimised St/PUDA ratio, we manufactured polyHIPEs with impact strength similar to that of commercial closed-cell polyurethane foam.

Polystyrene-interleaved carbon fibre reinforced epoxy composites exhibiting controllable stiffness have been manufactured. These composites undergo reductions in flexural stiffness of up to 99% when heated above the glass transition temperature T g of the interleaf layers. Potential applications for such materials include their use in morphing and deployable structures. Flexural tests at room temperature indicated that improvements in adhesion between the polystyrene and CFRP layers are required to prevent premature failure of the composites at low shear stresses. Here we investigate how modification of the interleaf layer improves the interlaminar shear strength of the laminates without affecting the stiffness loss at elevated temperatures. Two poly(styrene-co-maleic anhydride) (SMA) films with different maleic anhydride content were prepared and used as interleaf films. Thick adherend shear tests showed that the adhesion strength more than doubled, while flexural tests showed that composites containing SMA interleafs had more than twice the apparent flexural strength of composites containing pure polystyrene layers at 25 °C and yet still undergo significant reductions in stiffness at elevated temperature.

A powder based processing route was developed to allow manufacturing of thermosetting nanocomposites with high (20 wt%) carbon nanotube (CNT) loading fractions. Adaptation of high shear mixing methods, as used in thermoplastic processing, ensured that the CNTs were well distributed and dispersed even at the highest loadings. By minimising flow distances, compression moulding of powders ensured that the CNTs did not agglomerate during consolidation, and yielded a percolated CNT network in a nanocomposite with excellent electrical and thermal conductivities of 67 S m−1 and 0.77 W m−1 K−1, respectively. Unusually, the CNTs provided effective mechanical reinforcement at even the highest loadings; embrittlement is minimised by avoiding large scale inhomogeneities and the maximum measured Young's modulus (5.4 GPa) and yield strength (90 MPa) could make the nanocomposite an attractive matrix for continuous fibre composites. The macromechanical measurements were interpolated using micromechanical models that were previously successfully applied at the nanoscale.

A wet powder impregnation route to manufacture carbon fibre reinforced thermoplastic composites was adapted to accommodate thermosetting matrices reinforced with high fractions (20 wt%/13.6 vol%) of multiwalled carbon nanotubes (CNTs). The produced carbon fibre prepregs were consolidated into laminates with fibre volume fractions of 50–58% and up to 6.1 vol% CNTs. Microscopic imaging confirmed successful consolidation at intermediate CNT loadings, but some voidage at the highest CNT loading due to the highly viscoelastic uncured matrix. Nonetheless, through-thickness electrical conductivity and Mode I interlaminar fracture toughness were enhanced by as much as 152% and 24% to unprecedented values of σ = 53 S m−1 and GIC = 840 J m−2, respectively. Fractographic characterisation indicated that crack deflection was the mechanism responsible for the improved fracture toughness. The material properties were shown to be strongly dependent on the microstructure of the matrix.

Nitrates seriously affect drinking water quality. We herein present a process for the efficient removal of nitrates from water using a nanopaper ion-exchanger, which can be operated in flow-through conditions. The nanopaper ion-exchanger was produced from nanofibrillated cellulose obtained from fibre sludge, a paper-production waste stream, using a simple paper-making process. The cellulose nanofibrils were modified with quaternary trimethylammonium groups. The performance of these cationic nanopaper ion-exchangers was assessed with respect to their permeance and nitrate adsorption. Nitrates could be successfully captured onto the cationic nanopaper and thus rejected from contaminated water during dynamic filtration experiments. The ion-exchange nanopaper had adsorption capacities in the range of commercial available adsorbers but with the advantage of reduced contact time.

This work presents an investigation into how the pore diameter, pore throat diameter and permeability of emulsion templated macroporous polymers (polyM/HIPE) can be controlled by the energy input to the original surfactant stabilized medium/high internal phase emulsion (M/HIPE) template. Templates with internal phase volumes of 60%, 70% and 80% were examined. It was found that the equations used for predicting droplet size in emulsions are also suitable for predicting pore size in emulsion templated macroporous polymers. Pores were found to be larger for macroporous polymers produced from emulsions with lower internal phase volume ratios for the same energy input to the emulsion template. The relative size of pore throats compared to that of the pores was found to increase with decreasing mean pore size especially those produced from emulsions with 80% internal phase volumes. Gas permeability was found to increase linearly with pore throat diameter of polymers with similar porosity but decreases with decreasing porosity. However it was possible to produce highly permeable macroporous polymers by polymerisation of MIPEs with an internal phase percentage of 60% if the energy input during emulsification was minimal as this resulted in larger droplets leading to larger pore and pore throat sizes in the polyMIPE. However high levels of coalescence in the template emulsion prior to polymerisation were seen to drastically decrease the permeability of the resulting macroporous polymers.

Safe, light, and high-performance engineering structures may be generated by adopting composite materials with stable damage process (i.e., without catastrophic delamination). Interlayer hybrid composites may fail stably by suppressing catastrophic interlayer delamination. This paper provides a detailed analysis of delamination occurring in poly(acrylonitrile-butadiene-styrene) (ABS) or polystyrene (PS) film interleaved carbon-glass/epoxy hybrid composites. The ABS films toughened the interfaces of the hybrid laminates, generating materials with higher mode II interlaminar fracture toughness (GIIC), delamination stress (&sigma, del), and eliminating the stress drops observed in the reference baseline material, i.e., without interleaf films, during tensile tests. Furthermore, stable behaviour was achieved by treating the ABS films in oxygen plasma. The mechanical performance (GIIC and &sigma, del) of hybrid composites containing PS films, were initially reduced but increased after oxygen plasma treatment. The plasma treatment introduced O-C=O and O-C-O-O functional groups on the PS surfaces, enabling better epoxy/PS interactions. Microscopy analysis provided evidence of the toughening mechanisms, i.e., crack deflection, leading plasma-treated PS to stabilise delamination.

An integrated gaseous transport apparatus was designed not only to measure permeability (by the pressure rise technique) but also to study both steady state and (importantly) transient diffusion of oxygen in nitrogen in the pores of a porous material. The apparatus allows for the characterisation of porous media with a wide range of permeabilities and yielded accurate values of the viscous permeability and the slip flow coefficient. Experiments were also carried out in the non-Darcy flow regime. The diffusion measurements provide information on the ratio of the diffusion coefficient in the media to that in free space; this ratio is also a specific property of porous media. Combining the steady state and transient diffusion measurements, it was possible to deduce the effective porosity and the pore length. Berea sandstones with a range of porosities were analysed using both techniques and the results of the measurements are presented.

Fungal chitin is attracting commercial and academic interest as a cheap, renewable, easily isolated and abundant alternative to crustacean chitin. Being covalently decorated with β-glucan, fungal chitin exhibits a native nanocomposite architecture that varies in fibre diameter and chitin to β-glucan ratio from species to species, resulting in mechanical properties ranging from brittle, high tensile strength, plastic-like properties to very tough and elastomeric rubber-like tensile properties if processed into paper form. This study utilised a mild alkaline process to extract chitin-β-glucan complexes from tree bracket fungi (D. confragosa) and common mushrooms (A. bisporus), which were then combined in varying ratios and hot pressed to form engineered composite nanopapers with tunable tensile properties. Fruiting bodies of common mushrooms, with almost proportional contents of chitin and β-glucan, exhibited a nanofibrous architecture resulting in very high tensile strengths, far outperforming crustacean-derived chitin. These nanopapers could then be plasticised in a controlled fashion through addition of extract from tree bracket fungi, which contains large quantities of β-glucan, to produce composite nanopapers. The fungal chitin extracts were significantly more hydrophobic than crustacean chitin, suggesting potential as a coating agent for hydrophilic materials, such as cellulose. These remarkable and controllable characteristics make fungi-derived materials versatile for a wide range of applications, including coatings, membranes, packaging and paper.

Nano-engineered fibre/matrix interfaces can improve state-of-the-art fibre-reinforced composites. Grafting carbon nanotubes (CNTs) to high temperature quartz glass fibres produces “hairy” or “fuzzy” fibres, which combine reinforcements at micrometre and nanometre length scales. Fuzzy quartz fibres were produced continuously, reel-to-reel, on whole tows, in an open chemical vapour deposition reactor. The resulting uniform coverage of 200 nm long CNTs increased the interfacial shear strength with epoxy (90.3 ± 2.1 MPa) by 12% compared to the commercially-sized counterpart, as measured by single fibre pull-out tests. The improved interfacial properties were confirmed at the macroscale using unidirectional hierarchical bundle composites, which exhibited a delayed onset of fibre/matrix debonding. Although the quartz fibres are electrically insulating, the grafted CNT create a conductive path, predominantly parallel to the fibres. To explore the applicability for structural health monitoring, the resistivity was recorded in situ during mechanical testing, and correlated with simultaneous acoustic emission data. The baseline resistivity parallel to the fibres (ρ0 = 3.9 ± 0.4 × 10−1 Ω m) displayed a linear piezoresistive response (K = 3.64) until failure at ca. 2.1% strain, also referred to as "gauge factor”, a two-fold improvement over traditional resistance strain gauges (e.g. constantan). Hierarchical, fuzzy quartz fibres, therefore, simultaneously enhance both structural and sensing performance, offering multifunctional opportunities in large composite parts.