Fabrication and characterization of carbon-based nanocomposite membranes for packaging application

Multifunctional Cyclic Olefin Copolymer-Titanium Dioxide-Based Nanocomposites for Enhanced Antibacterial and Biocompatible Properties

The growing demand for multifunctional materials in biomedical and packaging applications necessitates the development of advanced nanocomposites with superior mechanical, barrier, and antibacterial properties. This study presents cyclic olefin copolymer (COC)/titanium dioxide (TiO2) nanocomposite films fabricated through the facile solution casting method, incorporating TiO2 at concentrations of 1, 3, and 5 wt %. Structural and morphological analyses confirmed effective TiO2 dispersion at lower concentrations, while agglomeration was observed at 5 wt %. The incorporation of TiO2 significantly enhanced barrier properties, reducing water vapor permeability from 80.67 to 29.99 g/m2 h and oxygen permeability from 7.66 to 2.78 mg/mL. Mechanical properties showed marked improvement, with tensile strength increasing by 113% and tensile modulus by 81.3% at 3 wt % TiO2. Antibacterial tests demonstrated efficacy against Escherichia coli and Staphylococcus aureus, while cytotoxicity studies confirmed the biocompatibility of the films. These findings highlight the potential of COC/TiO2 nanocomposites for applications, such as antibacterial coatings, wound healing patches, and high-performance packaging.

Bio-based composite film from konjac flour and dialdehyde starch: Development, properties and structural features

The development of environmental-friendly composite products from renewable resources has been considered as an excellent approach to address the negative impact of petroleum-based plastics on environment. Konjac flour (KF), as an excellent polysaccharide material, has a broad application in food field. It shows a promising future in the film field due to its excellent film-forming properties. In this work, KF was selected as primary film-forming matrix, and dialdehyde starch (DAS) as the reinforcing component. A series of KF/DAS composite films were prepared by adjusting the addition ratio of DAS component. Then, their physical and mechanical properties were characterized and analyzed. The results showed that KF/DAS composite film with 25 % DAS content exhibited the optimal mechanical properties, including tensile strength (TS) of 13.1 MPa and elongation at break (EAB) of 93.7 %, indicating that an excellent cross-linked system formed among KF and DAS utilizing the method described in this study. Furthermore, much evidences from the fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) confirmed that a strong chemical cross-linkages between DAS and KF via Schiff base and esterification reactions. Based on the thermogravimetry (TG) and scanning electron microscopy (SEM) results, KF/DAS composite films also had excellent thermal stability and a dense microstructure, although there are also changes with the DAS usage.

High-performance carboxymethyl starch/PVA based intelligent packaging films engineered with Cu-Trp nanocrystal as functional compatibilizer

A spindle-like Cu-based framework (Cu-Trp, Trp = L-Tryptophan) nanocrystal with ammonia-responsiveness was fabricated via simple aqueous solution approach, and it was subsequently explored as a functional compatibilizer of carboxymethyl starch/polyvinyl alcohol (CMS/PVA) blend toward constructing high-performance intelligent packaging films. The results showed that incorporation of Cu-Trp nanocrystal into CMS/PVA blend resulted in significant promotions regarding to the compatibility, mechanical strength (42.92 MPa), UV-blocking (with UV transmittance of only 2.4%), and water vapor barrier effectiveness of the blend film. Besides, the constructed CMS/PVA/Cu-Trp nanocomposite film exhibited superb long-term color stability, favorable antibacterial capacity (over 98.0%) toward both E. coli and S. aureus bacteria, as well as color change ability under ammonia environment. Importantly, the application trial confirmed that the CMS/PVA/Cu-Trp nanocomposite film is capable of visually monitoring shrimp spoilage during storage. These results implied that the CMS/PVA/Cu-Trp nanocomposite film holds tremendous potential as an intelligent active packaging material.

Developing colorimetric ammonia-sensing nanocomposite films based on potato starch/PVA and ZnCu-BTC nanorods for real-time monitoring food freshness

Smart packaging material capable of real-time monitoring of food freshness is essential for ensuring food safe. At present, colorimetric ammonia-sensing smart film often possesses issues with complicated production, high cost, and inferior long-term colour stability. Herein, Zinc‑copper bimetallic organic framework (ZnCu-BTC, BTC = 1,3,5-benzenetricarboxylate acid) nanorods with colorimetric ammonia-responsiveness were synthesized by adopting facile aqueous solution method, which were then explored as nano inclusions in potato starch/polyvinyl alcohol (PS/PVA) composite film towards developing high-performance smart packaging material. The results demonstrated that the introduction of ZnCu-BTC nanorods within PS/PVA brought about remarkable improvement in blend compatibility, accompanied by a boost in tensile strength to 47.2 MPa, as well as enhanced ultraviolet (UV) blocking efficacy (over 95.0 %). Additionally, the barrier properties of PS/PVA film against water vapor and oxygen were fortified due to the addition of ZnCu-BTC. More importantly, the developed PS/PVA/ZnCu-BTC nanocomposite film displayed satisfactory antibacterial activity (over 99 %) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), favorable colorimetric ammonia-sensing ability, and long-term colour stability. The ZnCu-BTC incorporated PS/PVA nanocomposite film could grant real-time detection of prawn freshness decline via remarkable colour change, indicating vast promise for smart food packaging applications.

Preparation and fire resistance modification on tannin-based non-isocyanate polyurethane (NIPU) rigid foams

Non-isocyanate polyurethane (NIPU) as a new type of polyurethane material has become a hot research topic in the polyurethane industry due to its no utilization of toxic isocyanates during the synthesis process. And the developing on recyclable biomass materials has also much attention in the industrial sector, hence the preparation and application of bio-based NIPU has also become a very meaningful study work. So, in this paper, tannin as a biomass material was used to synthesize tannin based non-isocyanate polyurethanes (TNIPU) resin, and then successfully prepared a self-blowing TNIPU foam at room temperature by using formic acid as initiator and glutaraldehyde as cross-linking agent. The compressive strength of this foam as high as 0.8 MPa, which is an excellent compressive performance. Meanwhile it will return to the state before compression when removing the pressure. This indicating that the foam has good toughness. In addition, formic acid can react with the amino groups in TNIPU to form amide substances, and generated enough heat to initiate the foaming process. Glutaraldehyde, as a crosslinking agent, reacts with the amino group in TNIPU to form a network structure system. By scanning electron microscope (SEM) observation of the cell shapes, it can be seen that the foam cells were uniform in size and shape, and the cell pores showed open and closed cells. The limiting oxygen index (LOI) tested value of this TNIPU foam is 24.45 % without any flame retardant added, but compared to the LOI value of polyurethane foam (17 %-19 %), TNIPU foam reveal a better fire resistance. It has a wider application prospect.

UiO66-based molecularly imprinted polymers with water-compatible deep eutectic solvent as functional monomer for purification of lysozyme from egg white

Protein-templated molecularly imprinted polymers have limitations such as poor mass transfer, slow recognition kinetics, and difficulties in isolation and purification due to their large molecular sizes, complex structures, and flexible conformations. To address these limitations and obtain lysozyme (Lyz)-imprinted polymers, a molecularly imprinted polymer (UiO66@DES-MIPs) was prepared for the first time by using Lyz as a template molecule, a metal-organic framework (UiO66-NH2) as a matrix, and a water-compatible deep eutectic solvent (DES) as a functional monomer. The introduction of UiO66-NH2 by the solvothermal method with a large specific surface area and favorable stability and resistance to environmental disturbances into the MIPs can reduce the "embedding" phenomenon and acquire a higher binding capacity and fast mass transfer. In addition, a water-soluble binary DES (1:2 molar ratio of choline chloride to 1,3 dimethylurea) prepared by a hydrothermal method as a functional monomer generates multiple forces with Lyz, increasing the hydrophilicity of UiO66@DES-MIPs and contributing to the formation and stabilization of the imprinted sites. Consequently, UiO66@DES-MIPs exhibited good selectivity, water compatibility, and fast adsorption equilibrium (the adsorption equilibrated at 243.87 ± 4.88 mg g-1 in 90 min). Besides, reusability experiments indicated that the UiO66@DES-MIPs could be recycled six times without obvious loss of adsorption capacity. The imprinting factor of UiO66@DES-MIPs is 3.67. The isolation and purification of Lyz from egg white confirmed the practicability of UiO66@DES-MIPs. The high adsorption capacity and specific recognition make this polymer a promising candidate for the isolation and purification of biological macromolecules.