Preparation and characterization of polylactic acid/polyaniline/nanocrystalline cellulose nanocomposite films

Sodium alginate-based indicator film with enhanced physicochemical properties induced by cellulose nanocrystals and monitor the freshness of chilled meat

Intelligent indicator films with colorimetric pH indicator properties were developed, incorporating black soybean seed coat anthocyanin (BA), cellulose nanocrystals (CNC), and sodium alginate (SA) to monitor meat freshness. The effect of different CNC additions on the microstructure, water barrier properties of the films, and BA release kinetics were comprehensively investigated. The results showed that with the increasement of CNC addition, the mechanical properties of SA/BA/CNC films were improved, the water contact angle significantly increased from 51.6° to 69°. Moreover, water solubility, vapor adsorption, and permeability significantly decreased, indicating enhanced water barrier properties. The release kinetic results showed that BA was released rapidly within 72 h and slowly thereafter, and its release process was described by Fick's model. Films with 7 % and 10 % CNC had lower BA diffusion coefficients. Their diffusions were formulated as linear regression equations (y = nx + a), where R2 was >0.80 and n was <0.50. Structural characterization showed that CNC immobilized BA mainly through hydrogen bonding, forming compact network microstructures with SA and BA. Meat freshness monitoring results showed that the film containing 7 % CNC showed visible color changes with increasing total volatile basic nitrogen and pH, along with low BA release, high water barrier and mechanical properties. Therefore, CNC has great potential for improving the physicochemical properties of indicator films, and the intelligent colorimetric indicator film could be applied to various food product.

Development of starch-cellulose composite films with antimicrobial potential

This study explored the structure and performance of starch-based antibacterial films reinforced with black tea cellulose nanocrystals (BT-CNCs). The optimal addition amount of BT-CNCs is 5 % (w/w Starch). This nanocrystal-infused film, incorporating chitosan (CS), ε-polylysine (ε-PL), and zinc oxide nanoparticles (ZnONP) as antibacterial agents, exhibited a smooth, continuous surface. The addition of BT-CNCs and antibacterial agents did not change the group characteristic peaks of the film, but changed the crystallinity slightly. The films, namely St, St/CNCs, St/CNCs/CS, and St/CNCs/ε-P, maintained high light transmittance (above 80 %), except for the St/CNCs/ZnONP film, which effectively shielded UV radiation. The combined use of antibacterial agents and BT-CNCs enhanced the water and oxygen barrier properties of the film. Notably, the St/CNCs/CS film exhibited the lowest solubility (17.74 % ± 0.36) and the highest tensile strength (14.23 ± 0.16 MPa). The antibacterial efficacy of the films decreased in the order of St/CNCs/ZnONP, St/CNCs/ε-PL, and St/CNCs/CS, with a more pronounced inhibitory effect on E. coli compared to S. aureus. This study marries natural waste recycling with cutting-edge food packaging technology, setting a new benchmark for the development of sustainable packaging materials.

Synthesis and characterization of polyaniline-based composites using cellulose nanocrystals as biological templates

Polyaniline (PANI) is considered as an ideal electrode material due to its remarkable Faradaic activity, exceptional conductivity, and ease of processing. However, the agglomeration and poor cycling stability of PANI largely limit its practical utilization in energy storage devices. To address these challenges, PANI was synthesized via a facile one-pot, two-step process using cellulose nanocrystals (CNCs) as bio-templates in this work. Zeta potential and particle size measurements revealed that the CNC template could impart improved dispersion stability to the synthesized PANI, which exhibited a decrease in average particle size from 1100 nm to 300 nm as a function of 10 % CNCs. Furthermore, the effect of CNC loadings on the performance of PANI was systematically investigated. The results showed that the specific capacitance of PANI/CNC increased from 102.52 F·g-1 to 138.12 F·g-1 with the CNC loading increase from 0 to 10 wt%. Particularly, the PANI/CNC composite film with a 1:9 ratio (C-P-10 %) demonstrated a capacity retention of 84.45 % after 6000 cycles and an outstanding conductivity of 526 S·m-1. This work generally offers an effective solution for the preparation of high-performance PANI-based composites, which might hold great promise in energy storage device applications.

Production of PLA/cellulose derived from pineapple leaves as bio-degradable mulch film

Mulch films were fabricated from polylactic acid (PLA) with cellulose nanocrystals (PNC) extracted from pineapple leaves. The PNC was modified by incorporating 4 wt% triethoxyvinylsilane (TEVS), designated as 4PNC, to enhance its interaction with PLA. The films incorporated varying concentrations of PNC (1, 2, 4, and 8 wt%). The results indicated that higher PNC concentrations increased the water vapor permeability (WVP) and biodegradability of the composite films, while reducing light transmission. Films containing 4PNC, particularly at 4 wt% (PLA/4PNC-4), exhibited an 11.18 % increase in elongation at break compared to neat PLA films. Moreover, these films showed reduced light transmission, correlating with decreased weed growth, reduced WVP, and enhanced barrier properties, indicative of improved soil moisture retention. Additionally, PLA films with 4PNC demonstrated greater thermal degradation stability than those with unmodified PNC, suggesting enhanced heat resistance. However, there was no significant difference in aerobic biodegradation between the PLA films with PNC and those with 4PNC. This study confirms that TEVS-modified cellulose significantly enhances the properties of bio-composite films, making them more suitable for mulch film applications.

Nanocrystalline cellulose as a reinforcing agent for poly (vinyl alcohol)/ gellan-gum-based composite film for moxifloxacin ocular delivery

Nanocrystalline cellulose (NCC) is a star material in drug delivery applications due to its good biocompatibility, large specific surface area, high tensile strength (TS), and high hydrophilicity. Poly(Vinyl Alcohol)/Gellan-gum-based innovative composite film has been prepared using nanocrystalline cellulose (PVA/GG/NCC) as a strengthening agent for ocular delivery of moxifloxacin (MOX) via solvent casting method. Impedance analysis was studied using the capacitive sensing technique for examining new capacitance nature of the nanocomposite MOX film. Antimicrobial properties of films were evaluated using Pseudomonas aeruginosa and Staphylococcus aureus as gram-negative and gram-positive bacteria respectively by disc diffusion technique. XRD revealed the characteristic peak of NCC and the amorphous form of the drug. Sustained in vitro release and enhanced corneal permeation of drug were noticed in the presence of NCC. Polymer matrix enhanced the mechanical properties (tensile strength 22.05 to 28.41 MPa) and impedance behavior (resistance 59.23 to 213.23 Ω) in the film due to the presence of NCC rather than its absence (16.78 MPa and 39.03 Ω respectively). Occurrence of NCC brought about good antimicrobial behavior (both gram-positive and gram-negative) of the film. NCC incorporated poly(vinyl alcohol)/gellan-gum-based composite film exhibited increased mechanical properties and impedance behavior for improved ocular delivery of moxifloxacin.

Effects of modified elastin-collagen matrix on the thermal and mechanical properties of Poly (lactic acid)

Poly (lactic acid) (PLA) has distinctive characteristics, including biodegradability, biocompatibility, thermal process ability, high transparency and good film-forming ability. However, PLA has some poor properties that limit its wide applicability. These properties include a low crystallization rate, poor thermal stability, and high brittleness. The main objective of this research was to investigate the effect of a modified elastin-collagen (m-ELA-COLL) matrix on the properties of PLA. The ELA-COLL matrix was extracted from broiler skin waste and modified by grafting using lactic acid monomer to facilitate compatibility with PLA. The extracted and modified ELA-COLL matrix was investigated using FTIR, and α-helix and β-sheet structures were confirmed in both cases (pre- and post-modifications). Modified elastin-collagen dispersed Poly (lactic acid) (PLA-m-ELA-COLL) blend films were prepared using the solution casting method and characterized using DSC and UTM. The effect of m-ELA-COLL as a nucleating agent resulted in the degree of crystallinity improvement of 58.8% with 10 wt% m-ELA/COLL loading, and the elongation at break was improved by 161.3% for PLA-40%-m-ELA-COLL with a tensile strength of 33.75 MPa. The results obtained revealed that the biofilms can be considered as a good candidate to be studied further in the packaging industry.

Essential characteristics improvement of metallic nanoparticles loaded carbohydrate polymeric films - A review

Petroleum-based films have contributed immensely to various environmental issues. Developing green-based films from carbohydrate polymers is crucial for addressing the harms encountered. However, some limitations exist on their property, processibility, and applicability that prohibit their processing for further developments. This review discusses the potential carbohydrate polymers and their sources, film preparation methods, such as solvent-casting, tape-casting, extrusion, and thermo-mechanical compressions for green-based films using various biological polymers with their merits and demerits. Research outcomes revealed that the essential characteristics improvement achieved by incorporating different metallic nanoparticles has significantly reformed the properties of biofilms, including crystallization, mechanical stability, thermal stability, barrier function, and antimicrobial activity. The property-enhanced bio-based films made with nanoparticles are potentially interested in replacing fossil-based films in various areas, including food-packaging applications. The review paves a new way for the commercial use of numerous carbohydrate polymers to help maintain a sustainable green environment.

Sugarcane leave-derived cellulose nanocrystal/graphene oxide filter membrane for efficient removal of particulate matter

The goal of this study is to isolate cellulose nanocrystals (CNC) from sugarcane leaves (SCL) and fabricate filter membranes. Filter membranes consisting of the CNC and varying amount graphene oxide (GO) were fabricated using vacuum filtration technique. The α-cellulose content increased from 53.56 ± 0.49 % in untreated SCL to 78.44 ± 0.56 % and 84.99 ± 0.44 % in steam-exploded and bleached fibers, respectively. Atomic force microscopy (AFM) and transmission electron microscope (TEM) of CNC isolated from SCL indicated nanosized particles in the range of 7.3 nm and 150 nm for diameter and length, respectively. Morphologies of the fiber and CNC/GO membranes were determined by scanning electron microscopy (SEM) and crystallinity by X-ray diffraction (XRD) analysis of crystal lattice. The crystallinity index of CNC decreased with the addition of GO into the membranes. The CNC/GO-2 recorded the highest tensile index of 3.001 MPa. The removal efficiency increases with increasing GO content. The highest removal efficiency of 98.08 % was recorded for CNC/GO-2. CNC/GO-2 membrane reduced growth of Escherichia coli to 65 CFU compared to >300 CFU of control sample. SCL is a potential bioresource for isolation of cellulose nanocrystals and fabrication of high-efficiency filter membrane for particulate matter removal and inhibition of bacteria.

Emerging Applications of Versatile Polyaniline-Based Polymers in the Food Industry

Intrinsically conducting polymers (ICPs) have been widely studied in various applications, such as sensors, tissue engineering, drug delivery, and semiconductors. Specifically, polyaniline (PANI) stands out in food industry applications due to its advantageous reversible redox properties, electrical conductivity, and simple modification. The rising concerns about food safety and security have encouraged the development of PANI as an antioxidant, antimicrobial agent, food freshness indicator, and electronic nose. At the same time, it plays an important role in food safety control to ensure the quality of food. This study reviews the emerging applications of PANI in the food industry. It has been found that the versatile applications of PANI allow the advancement of modern active and intelligent food packaging and better food quality monitoring systems.

Preparation and Characterization of Degradable Cellulose−Based Paper with Superhydrophobic, Antibacterial, and Barrier Properties for Food Packaging

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and nano silica−modified stearic acid (SA/SiO2) as a superhydrophobic layer. As comprehensively investigated by various tests, results showed that the as−prepared packages possessed excellent thermal stability attributed to inorganic SiO2 incorporation. The excellent film−forming characteristics of PLA improved the tensile strength of the manufactured papers (104.3 MPa) as compared to the original cellulose papers (70.50 MPa), enhanced by 47.94%. Benefiting from the rough nanostructure which was surface−modified by low surface energy SA, the contact angle of the composite papers attained 156.3°, owning superhydrophobic performance for various liquids. Moreover, the composite papers showed excellent gas, moisture, and oil bacteria barrier property as a result of the reinforcement by the functional coatings. The Cobb300s and WVP of the composite papers were reduced by 100% and 88.56%, respectively, and their antibacterial efficiency was about 100%. As the novel composite papers have remarkable thermal stability, tensile strength, and barrier property, they can be exploited as a potential candidate for eco−friendly, renewable, and biodegradable cellulose paper−based composites for the substitute of petroleum−derived packages.

Characterization of active and pH-sensitive poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) films containing essential oils and anthocyanin for food packaging application

Active and pH-sensitive films of poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) have been fabricated and tested. The PLA and PLA/NFC films with 1.5% NFC were prepared via solvent casting method, with different loadings of essential oil (EO), including thymol and curry, being added at 5, 10, and 15%. The fixed content of anthocyanin powder (1%) was incorporated into the films as a pH indicator. The active PLA and PLA/NFC films were characterised on their physical, mechanical, thermal, and biodegradation properties. The addition of NFC reduced the tensile strength but increased the flexibility of films due to the plasticizing effect of EOs. The PLA/EO and PLA/NFC/EO films containing curry demonstrated a slightly higher strength than the films with thymol. The flexibility of films was increased at higher loading of EO regardless of the types of EO. The thermal profile demonstrated that the neat PLA film had a higher maximum degradation temperature than the active PLA/EO and PLA/NFC/EO films. The active PLA/EO and PLA/NFC/EO films containing anthocyanin successfully changed its colour in pH 2.0 and 14.0. The PLA/NFC films with thymol and anthocyanin formulation could inhibit fungus growth better in the cherry tomato sample than the PLA/NFC films with curry and anthocyanin.

Characterization of Natural Anthocyanin Indicator Based on Cellulose Bio-Composite Film for Monitoring the Freshness of Chicken Tenderloin

Intelligent packaging with indicators that provide information about the quality of food products can inform the consumer regarding food safety and reduce food waste. A solid material for a pH-responsive indicator was developed from hydroxypropyl methylcellulose (HPMC) composited with microcrystalline cellulose (MCC). MCC at 5%, 10%, 20%, and 30% w/w was introduced into the HPMC matrix and the physical, barrier, thermal, and optical properties of the HPMC/MCC bio-composite (HMB) films were analyzed. At 5, 10, and 20% MCC, improved mechanical, transparency, and barrier properties were observed, where HMB with 20% of MCC (H20MB) showed the best performance. Therefore, H20MB was selected as the biodegradable solid material for fabricating Roselle anthocyanins (RA) pH sensing indicators. The performance of the RA-H20MB indicator was evaluated by monitoring its response to ammonia vapor and tracking freshness status of chicken tenderloin. The RA-H20MB showed a clear color change with respect to ammonia exposure and quality change of chicken tenderloin; the color changed from red to magenta, purple and green, respectively. These results indicated that RA-H20MB can be used as a biodegradable pH sensing indicator to determine food quality and freshness.

Preparation of bio-based cellulose acetate/chitosan composite film with oxygen and water resistant properties

Plastic pollution has inspired the preparation of environmentally friendly bio-based plastics that can replace petroleum-based plastics. Herein, a composite film with oxygen and water resistant properties was prepared by a fluidized bed method, employing bio-based cellulose acetate (CA) as raw material, glycerol as a plasticizer, and chitosan and silica as additives. The addition of 15% chitosan greatly reduced the oxygen transmission rate of the CA film by 83.5%, and increased the tensile stress and tensile strain of the composite membrane, reaching 26.5 MPa and 22.2%, respectively. The deposition of silica particles is able to compensate for the undesired increase in the hydrophilicity caused by the addition of chitosan, and tune the hydrophilic nature of the surface of the CA/CS films to the hydrophobic nature, which is desirable for water-resistant applications. The prepared composite film displays good oxygen and water resistant properties and can be used for food packaging and related applications.

Development and characterisation of packaging film from Napier cellulose nanowhisker reinforced polylactic acid (PLA) bionanocomposites

A packaging material that is environment-friendly with excellent mechanical and physicochemical properties, biodegradable and ultraviolet (UV) protection and thermal stability was prepared to reduce plastic waste. Six different concentrations of Pennisetum purpureum/Napier cellulose nanowhiskers (NWCs) (i.e. 0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt%) were used to reinforce polylactic acid (PLA) by a solvent casting method. The resulting bionanocomposite film samples were characterised in terms of their morphology, chemical structure, crystallinity, thermal degradation and stability, light transmittance, water absorption, biodegradability, and physical and mechanical properties. Field-emission scanning electron microscopy showed the excellent dispersion of NWC in the PLA matrix occurred with NWC concentrations of 0.5-1.5 wt%. All the bionanocomposite film samples exhibited good thermal stability at approximately 343-359 °C. The highest water absorption was 1.94%. The lowest transparency at λ₈₀₀ was 16.16% for the PLA/3.0% NWC bionanocomposite film, which also has the lowest UVA and UVB transmittance of 7.49% and 4.02%, respectively, making it suitable for packaging materials. The PLA/1.0% NWC film exhibited the highest crystallinity of 50.09% and high tensile strength and tensile modulus of 21.22 MPa and 11.35 MPa, respectively.

Fabrication and characterization of polylactic acid coaxial antibacterial nanofibers embedded with cinnamaldehyde/tea polyphenol with food packaging potential

Polylactic acid (PLA) is a promising food packaging material with biocompatible, nontoxic and biodegradable. In order to reduce the deterioration of aquatic products caused by microorganisms, PLA coaxial nanofiber films with cinnamaldehyde (CMA), tea polyphenol (TP) and its composite as core materials were prepared by using coaxial electrospinning technology. Its microscopic morphology and structure were characterized separately, and its thermal stability, wettability and mechanical properties were determined. The antibacterial activity and antibacterial mechanism of nanofiber films were studied with Shewanella putrefaciens (S. putrefaciens) which is the dominant spoilage of aquatic products as the target of action. The results show that the CMA/TP (m/m = 2:5)-PLA coaxial nanofibers have small diameter, uniform distribution, smooth surface, no pores and fracture. At the same time, the film has strong hydrophobicity, good thermal stability and mechanical properties. Its antibacterial performance is better than that of single-core nanofiber films, which effectively destroys the cell membrane of S. putrefaciens, increases the permeability of cell membrane, and interferes with the synthesis and expression of its protein. The coaxial nanofiber films with CMA, TP and its composite as core material can be used as a fresh-keeping material with antibacterial properties, and has potential application value in the field of food preservation.

Investigation of Functionalized Surface Charges of Thermoplastic Starch/Zinc Oxide Nanocomposite Films Using Polyaniline: The Potential of Improved Antibacterial Properties

Improving the antibacterial activity of biodegradable materials is crucial for combatting widespread drug-resistant bacteria and plastic pollutants. In this work, we studied polyaniline (PANI)-functionalized zinc oxide nanoparticles (ZnO NPs) to improve surface charges. A PANI-functionalized ZnO NP surface was prepared using a simple impregnation technique. The PANI functionalization of ZnO successfully increased the positive surface charge of the ZnO NPs. In addition, PANI-functionalized ZnO improved mechanical properties and thermal stability. Besides those properties, the water permeability of the bionanocomposite films was decreased due to their increased hydrophobicity. PANI-functionalized ZnO NPs were applied to thermoplastic starch (TPS) films for physical properties and antibacterial studies using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The PANI-functionalized ZnO bionanocomposite films exhibited excellent antibacterial activity for both E. coli (76%) and S. aureus (72%). This result suggests that PANI-functionalized ZnO NPs can improve the antibacterial activity of TPS-based bionanocomposite films.

Effects of synthesised polyaniline (PAni) contents on the anti-static properties of PAni-based polylactic acid (PLA) films

An anti-static polymer film was prepared using biodegradable poly(lactic acid) as a matrix and polyaniline (PAni) as an anti-static agent. It is aimed to be applied in packaging applications to dissipate the accumulated charges. The anti-static properties of PLA films were investigated with various PAni contents ranging from 0% to 20% through ex situ polymerisation by the solution casting method. PAni was synthesised in the solution form through chemical oxidation at 0 °C. The synthesis of PAni was confirmed by Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-Vis) absorption spectroscopy. The mechanical and anti-static properties of the samples were characterised using a Universal Testing Machine (UTM) and a resistivity meter, respectively. The experimental results indicated that incorporation of PAni into PLA films affected the morphology, anti-static and mechanical properties of the samples. PLA/PAni showed a compact surface with a porous structure, reflecting the interfacial interaction between PLA and PAni in the presence of a plasticiser. It was discovered and compared with other compositions, PLA with 15% PAni exhibited excellent anti-static performance with 2.45 × 10¹⁰ ohm/sq surface resistivity and the highest tensile strength, elongation at break and modulus of 29.3 ± 2.4 MPa, 60.1 ± 1.6% and 1364.0 ± 85.2 MPa respectively. Hence, PAni is a good candidate to be used in PLA/PAni systems by giving a suitable surface resistivity that can potentially be applied in anti-static packaging applications.