High antibacterial and barrier properties of natural rubber comprising of silver-loaded graphene oxide

Wormwood-infused porous-CaCO3 for synthesizing antibacterial natural rubber latex

Wormwood leaf is a traditional Chinese herbal medicine with a high medicinal value and long application history and its essential oil is a high-purity plant oil extracted from Wormwood leaf. Pharmacological research reveals that Wormwood leaf and Wormwood essential oil are a broad-spectrum antibacterial and antiviral drug, which can inhibit and kill many bacteria and viruses. We loaded wormwood extract on porous calcium carbonate (Porous-CaCO3) and introduced it and Wormwood essential oil into Natural rubber latex (NRL), thus synthesizing NRL composites with excellent vitro and in vivo antibacterial effect, cell compatibility and mechanical properties. This NRL material can delay the light aging and thermal oxidation of some mechanical properties, which provides a broader avenue for its commercialization.

Graphene-Based Hybrid Fillers for Rubber Composites

Graphene and its derivatives have been confirmed to be among the best fillers for rubber due to their excellent properties, such as high mechanical strength, improved interface interaction, and strain-induced crystallization capabilities. Graphene rubber materials can be widely used in tires, shoes, high-barrier conductive seals, electromagnetic shielding seals, shock absorbers, etc. In order to reduce the graphene loading and endow more desirable functions to rubber materials, graphene-based hybrid fillers are extensively employed, which can effectively enhance the performance of rubber composites. This review briefly summarizes the recent research on rubber composites with graphene-based hybrid fillers consisting of carbon black, silica, carbon nanotubes, metal oxide, and one-dimensional nanowires. The preparation methods, performance improvements, and applications of different graphene-based hybrid fillers/rubber composites have been investigated. This study also focuses on methods that can ensure the effectiveness of graphene hybrid fillers in reinforcing rubber composites. Furthermore, the enhanced mechanism of graphene- and graphene derivative-based hybrid fillers in rubber composites is investigated to provide a foundation for future studies.

A Versatile Approach for the Synthesis of Antimicrobial Polymer Brushes on Natural Rubber/Graphene Oxide Composite Films via Surface-Initiated Atom-Transfer Radical Polymerization

A simple strategy was adopted for the preparation of an antimicrobial natural rubber/graphene oxide (NR/GO) composite film modified through the use of zwitterionic polymer brushes. An NR/GO composite film with antibacterial properties was prepared using a water-based solution-casting method. The composited GO was dispersed uniformly in the NR matrix and compensated for mechanical loss in the process of modification. Based on the high bromination activity of α-H in the structure of cis-polyisoprene, the composite films were brominated on the surface through the use of N-bromosuccinimide (NBS) under the irradiation of a 40 W tungsten lamp. Polymerization was carried out on the brominated films using sulfobetaine methacrylate (SBMA) as a monomer via surface-initiated atom transfer radical polymerization (SI-ATRP). The NR/GO composite films modified using polymer brushes (PSBMAs) exhibited 99.99% antimicrobial activity for resistance to Escherichia coli and Staphylococcus aureus. A novel polymer modification strategy for NR composite materials was established effectively, and the enhanced antimicrobial properties expand the application prospects in the medical field.

The impact of non-deproteinization on physicochemical and biological properties of natural rubber latex for biomedical applications

Latex is a colloidal suspension derived from the Hevea brasiliensis tree, derived from natural rubber, poly(isoprene), and assorted constituents including proteins and phospholipids. These constituents are inherent to both natural rubber and latex serum. This investigation was undertaken to examine the impact of the deproteinization process on chemical and biological dynamics of natural rubber latex. Natural Rubber (NR) extracted from the pure latex (LNCP) was obtained through centrifugation, followed by six rounds of solvent purification (LP6). The structure was characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), swelling test, surface zeta potential (ζ), scanning electron microscopy (SEM) and in vitro assay. The results revealed that the LP6 group presented decreased swelling kinetics, reduced cell adhesion and proliferation, and a smoother surface with decreased negative surface charge. Conversely, the LNCP group shown accelerated swelling, heightened adhesion and cellular growth, and a more negatively charged and rougher surface. As such, the attributes of latex serum and proteins have potential usage across numerous biomedical applications.

Boosting the Antibacterial Performance of Natural Rubber Latex Foam by Introducing Silver-Doped Zinc Oxide

Natural rubber (NR) latex foam is one of the rubber products that are increasingly in demand in the market. This is simply because of its lightweight, good thermal insulation, and resilience. The applications of NR latex foam are mostly for pillows and mattresses. This has resulted in these products requiring antibacterial performance which is very important for the safety of the end-users. In this study, the antibacterial NR latex foam was prepared by incorporating the silver-doped zinc oxide (Ag-doped ZnO) into the NR latex foam. Ag-doped ZnO was prepared by microwave-assisted method and then characterized through morphological characteristics and X-ray diffraction (XRD). The content of Ag doped onto ZnO was designed by varying the AgNO₃ content at 15 wt%, 50 wt%, and 100 wt% of ZnO. The results confirmed that the Ag was successfully doped onto ZnO. The silver particles were found to be in the 40-50 nm range, where the size of ZnO ranges between 300 and 400 nm, and the Ag attached to the ZnO particles. The XRD patterns of Ag-doped ZnO correspond to planes of hexagonal wurtzite ZnO structure and cubic metallic Ag. This Ag-doped ZnO was further added to NR latex foam. It was observed that Ag-doped ZnO did not affect the physical properties of the NR latex foam. However, it is clear that both the inhibition zone and percent reduction of bacteria (e.g., E. coli and S. aureus) were enhanced by the addition of Ag-doped ZnO. It showed a decrease in the amount of cell growth over contact time. The content of 100 wt% AgNO₃ could reduce E. coli and S. aureus up to 64.72% and 58.90%, respectively, when samples were maintained for 24 h. This study provides a scientific understanding of how Ag-doped ZnO could facilitate the development of eventual rubber foam products based on the respective results.