Conductive Polyaniline/Cellulose/Graphite Composite Films with High Thermal Stability and Antibacterial Activity

Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.

Nano-Cu2O-loaded Paper: Green Preparation and High Visible Light Photocatalytic Performance for Formaldehyde Removal

The removal of formaldehyde (HCHO) from indoor air is of great importance to reduce health risks and improve indoor air quality. In this study, nano-Cu2O-loaded paper with superior photocatalytic activity under visible light for the removal of HCHO was fabricated through a green, simple, and fast in situ synthesis method. The optimum preparation conditions for nano-Cu2O-loaded paper were as follows: 2 g (oven-dry basis) cellulose fibers, CuSO4 dosage 8 g, NaOH dosage 1.6 g, temperature 80℃, 60 min for Cu2+ absorption, and 60 min for reaction. Under the optimum conditions, the Cu2O deposition ratio approached 30% and the nano-Cu2O-loaded paper exhibited a catalytic efficiency of approximately 97% for HCHO removal. The photocatalytic capacity of nano-Cu2O-loaded paper for HCHO removal had a positive correlation with the deposition ratio of nano Cu2O particles. Excellent antibacterial property of nano- Cu2O-loaded paper against Staphylococcus aureus and Escherichia coli was also confirmed. Moreover, nano-Cu2O-loaded paper was proven to be hydrophobic.

Coaxing Polysaccharide Granules into Supramolecular Biocolloidal Additives for Papermaking

In light of developments in polysaccharide-based sustainable processes involving supramolecular interactions,we herein present our findings pertaining to coaxing polysaccharide granules into functional supramolecular biocolloids.Translucent biocolloidal dispersions containing various forms of starch are facilely designable,essentially built upon complexation between disassembled native cornstarch granules and amphiphilic ligands.Oily moieties of guest molecules are dynamically attractable into cavities of helical structures,with cationic groups pointing toward the bulk phase.This noncovalent attraction can generate core-shell biocolloidal particles.The significantly higher gelatinizability of freeze-dried biocolloids in contrast to native cornstarch granules is attributable to complex formation,and a homogenous dispersion is readily formable at room temperature.Our results also show biocolloids'ligand-related antibacterial activity.The use of biocolloids as wet-end additives for biofiber assemblies(cellulosic paper)can enhance mechanical strength,fines retention,and filler bondability.Supramolecular biocolloids with positively charged,translucent,easily gelatinizable,antibacterial,and polysaccharide-bondable functionalities would find tailorable use in the paper industry.

Improving Electrochemical Performance of Cellulose Fiber-based Supercapacitor Electrode Using Polypyrrole-wrapped Iron Oxyhydroxide

Polypyrrole(PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors.However,they cannot readily provide high specific capacitance and cyclic stability owing to their inherent drawbacks,such as high resistance,Weber impedance,and volume expansion or collapse during charging/discharging.In this study,iron oxyhydroxide(FeOOH)is incorporated in the abovementioned composite to decrease the equivalent series resistance,charge transfer resistance,and Weber impedance,thereby enhancing electron transfer and ion diffusion,which results in superior electrochemical performance.The PPy-wrapped FeOOH@cellulose fiber-based composite electrode with the molar ratio of FeSO_(4) to NaBH4 of 1∶1 exhibits a high specific capacitance of 513.8 F/g at a current density of 0.2 A/g,as well as an excellent capacitance retention of 89.4% after 1000 cycles.

Flexible Nanopaper Composed of Wood-Derived Nanofibrillated Cellulose and Graphene Building Blocks

Nanopaper has attracted considerable interest in the fields of films and paper research.However,the challenge of integrating the many advantages of nanopaper still remains.Herein,we developed a facile strategy to fabricate multifunctional nanocomposite paper(NGCP)composed of wood-derived nanofibrillated cellulose(NFC)and graphene as building blocks.NFC suspension was consisted of long and entangled NFCs(10–30 nm in width)and their aggregates.Before NGCP formation,NFC was chemically modified with a silane coupling agent to ensure that it could interact strongly with graphene in NGCP.The resulting NGCP samples were flexible and could be bent repeatedly without any structural damage.Within the NGCP samples,the high aspect ratio of NFC made a major contribution to its high mechanical strength,whereas the sheet-like graphene endowed the NGCP with electrical resistance and electrochemical activity.The mechanical strength of the NGCP samples decreased as their graphene content increased.However,the electrical resistance and electrochemical activity of the NGCP samples both rose with increasing content of graphene.The NGCPs still kept advantageous mechanical properties even at high temperatures around 300℃ because of the high thermal stability of NFCs and their strong entangled web-like structures.In view of its sustainable building blocks and multifunctional characteristics,the NGCP developed in this work is promising as low-cost and high-performance nanopaper.

Converting a Dilute Slurry of Hollow Tube-like Papermaking Fibers into Dynamic Hydrogels

Commercially,assembly-directed packing of hollow tube-like papermaking fibers with widths of roughly 10–50μm)into sustainable microfibrous bioassemblies(i.e.,paper-based products)starts with a dilute fiber slurry.In this process,a huge amount of water is required to disperse and transport fibers,which also facilitates colloidal interactions and formation of interfiber bonds.To form bioassemblies in their dry states,unit operations associated with dewatering and drying are routine practices,and treatment of the generated wastewater is a necessity.We herein present a facile,easily scalable concept of converting fiber slurry into dynamic hydrogels by using chemical additives(similar to papermaking wet-end additives),but without water removal.We used a typical group of additives as an example in an attempt to demonstrate the applicability of the concept.With boron-based dynamic chemistry as a key theoretical foundation,the combination of crosslinking and hydrogen bonding can lead to the formation of phase-reversible,self-healable,and stretchable hydrogels.Essentially,the characteristics of hydrogels are facilely tunable,and process parameters such as polymer dosage are rather critical.It is worth noting that fibers can act as a structural skeleton or mechanical support for tailorable design of hydrogels.The concept demonstrated in this study provides insights into value-added utilization of mass-producible biopolymeric fibers in accordance with existing industrial facilities.Fiber-based hydrogels would find use in diversified applications:toys,3D/4D printing materials,soft robots,drug delivery systems,among others.

Tailoring starch-engineered mineral particles towards enhanced interaction with cellulosic fibers

Interaction of unmodified starch with guest molecules or ligands(e.g.,fatty acids)as a basis for the formation of starch-encapsulated mineral filler particles is an effective process for mitigating the negative impact of filler addition on the strength properties of cellulosic networks.As unmodified starch is essentially nonionic,the interaction of starch-engineered fillers with negatively charged cellulosic fibers is somehow limited.Here,the concept of substituting unmodified starch with a minor amount of cationic starch in filler engineering with starch inclusion complexes was proposed.It was hypothesized that filler-fiber interaction would be enhanced by cationic-anionic attraction.Encouragingly,the effectiveness of this concept was demonstrated to be very pronounced.For instance,at a cationic starch percentage of 3%(relevant to the weight of total starch),filler retention and filler bondability with cellulosic fibers were significantly improved,leading to further mitigated negative impact of filler addition on tensile strength.Basically,this easily scalable concept may shed light on greener,more efficient use of filler technologies on the basis of starch inclusion complex formation,opening up new possibilities for real commercial applications.