Innovative Plasma Process of Grafting Methyl Diallyl Ammonium Salt onto Polypropylene to Impart Antibacterial and Hydrophilic Surface Properties

The Application Progress of Nonthermal Plasma Technology in the Modification of Bone Implant Materials

With the accelerating trend of global aging, bone damage caused by orthopedic diseases, such as osteoporosis and fractures, has become a shared international event. Traffic accidents, high-altitude falls, and other incidents are increasing daily, and the demand for bone implant treatment is also growing. Although extensive research has been conducted in the past decade to develop medical implants for bone regeneration and healing of body tissues, due to their low biocompatibility, weak bone integration ability, and high postoperative infection rates, pure titanium alloys, such as Ti-6A1-4V and Ti-6A1-7Nb, although widely used in clinical practice, have poor induction of phosphate deposition and wear resistance, and Ti-Zr alloy exhibits a lack of mechanical stability and processing complexity. In contrast, the Ti-Ni alloy exhibits toxicity and low thermal conductivity. Nonthermal plasma (NTP) has aroused widespread interest in synthesizing and modifying implanted materials. More and more researchers are using plasma to modify target catalysts such as changing the dispersion of active sites, adjusting electronic properties, enhancing metal carrier interactions, and changing their morphology. NTP provides an alternative option for catalysts in the modification processes of oxidation, reduction, etching, coating, and doping, especially for materials that cannot tolerate thermodynamic or thermosensitive reactions. This review will focus on applying NTP technology in bone implant material modification and analyze the overall performance of three common types of bone implant materials, including metals, ceramics, and polymers. The challenges faced by NTP material modification are also discussed.

Enhancing Polyvinyl Alcohol Nanocomposites with Carboxy-Functionalized Graphene: An In-Depth Analysis of Mechanical, Barrier, Electrical, Antibacterial, and Chemical Properties

To enhance the various properties of polyvinyl alcohol (PVA), varying concentrations of carboxy-functionalized graphene (CFG) were employed in the preparation of CFG/PVA nanocomposite films. FTIR and XRD analyses revealed that CFG, in contrast to graphene, not only possesses carboxylic acid group but also exhibits higher crystallinity. Mechanical testing indicated a notable superiority of CFG addition over graphene, with optimal mechanical properties such as tensile and yield strengths being achieved at a 3% CFG concentration. Relative to pure PVA, the tensile strength and yield strength of the composite increased by 2.07 and 2.01 times, respectively. XRD analysis showed distinct changes in the crystalline structure of PVA with the addition of CFG, highlighting the influence of CFG on the composite structure. FTIR and XPS analyses confirmed the formation of ester bonds between CFG and PVA, enhancing the overall performance of the material. TGA results also demonstrated that the presence of CFG enhanced the thermal stability of CFG/PVA nanocomposite films. However, analyses using scanning electron microscopy and transmission electron microscopy revealed that a 3% concentration of CFG was uniformly dispersed, whereas a 6% concentration of CFG caused aggregation of the nanofiller, leading to a decrease in performance. The incorporation of CFG significantly enhanced the water vapor and oxygen barrier properties of PVA, with the best performance observed at a 3% CFG concentration. Beyond this concentration, barrier properties were diminished owing to CFG aggregation. The study further demonstrated an increase in electrical conductivity and hydrophobicity of the nanocomposites with the addition of CFG. Antibacterial tests against E. coli showed that CFG/PVA nanocomposites exhibited excellent antibacterial properties, especially at higher CFG concentrations. These findings indicate that CFG/PVA nanocomposites, with an optimized CFG concentration, have significant potential for applications requiring enhanced mechanical strength, barrier properties, and antibacterial capabilities.

Plasma Surface Engineering of Natural and Sustainable Polymeric Derivatives and Their Potential Applications

Recently, natural as well as synthetic polymers have been receiving significant attention as candidates to replace non-renewable materials. With the exponential developments in the world each day, the collateral damage to the environment is incessant. Increased demands for reducing pollution and energy consumption are the driving force behind the research related to surface-modified natural fibers (NFs), polymers, and various derivatives of them such as natural-fiber-reinforced polymer composites. Natural fibers have received special attention for industrial applications due to their favorable characteristics, such as low cost, abundance, light weight, and biodegradable nature. Even though NFs offer many potential applications, they still face some challenges in terms of durability, strength, and processing. Many of these have been addressed by various surface modification methodologies and compositing with polymers. Among different surface treatment strategies, low-temperature plasma (LTP) surface treatment has recently received special attention for tailoring surface properties of different materials, including NFs and synthetic polymers, without affecting any of the bulk properties of these materials. Hence, it is very important to get an overview of the latest developments in this field. The present article attempts to give an overview of different materials such as NFs, synthetic polymers, and composites. Special attention was placed on the low-temperature plasma-based surface engineering of these materials for diverse applications, which include but are not limited to environmental remediation, packaging, biomedical devices, and sensor development.

Mechanical, Hydrophobic, and Barrier Properties of Nanocomposites of Modified Polypropylene Reinforced with Low-Content Attapulgite

Attapulgite (ATT) has never been used as a barrier additive in polypropylene (PP). As a filler, ATT should be added in high content to PP. However, that would result in increased costs. Moreover, the compatibility between ATT and the PP matrix is poor due to the lack of functional groups in PP. In this study, carboxylic groups were introduced to PP to form a modified polypropylene (MPP). ATT was purified, and a low content of it was added to MPP to prepare MPP/ATT nanocomposites. The analysis from FTIR indicated that ATT could react with MPP. According to the results of oxygen and water permeability tests, the barrier performance of the nanocomposite was optimal when the ATT content was 0.4%. This great improvement in barrier performance might be ascribed to the following three reasons: (1) The existence of ATT extended the penetration path of O₂ or H₂O molecules; (2) O₂ or H₂O molecules may be adsorbed and stored in the porous structure of ATT; (3) Most importantly, –COOH of MPP reacted with –OH on the surface of ATT, thereby the inner structure of the nanocomposite was denser, and it was less permeable to molecules. Therefore, nanocomposites prepared by adding ATT to MPP have excellent properties and low cost. They can be used as food packaging materials and for other related applications.

Barrier performance and biodegradability of antibacterial poly(butylene adipate-co-terephthalate) nanocomposites reinforced with a new MWCNT-ZnO nanomaterial

A new nanomaterial or nano-filler in the form of multiwalled carbon nanotube-zinc oxide (MWCNT-ZnO) was synthesized for the purpose of modifying poly(butylene adipate-co-terephthalate) (PBAT) and its derivative (modified PBAT or MPBAT) through a melt-blending method (MPBAT was obtained by introducing maleic anhydride groups into PBAT). The effect of the new nano-filler on the properties of resultant nanocomposites was determined from the characterization of mechanical properties, morphology, crystallinity, thermal stability, barrier properties, hydrophilicity, conductivity, antibacterial property, and biodegradability. The results showed that MPBAT nanocomposites had stronger mechanical properties, better barrier properties, and higher electrical conductivity than PBAT nanocomposites. Scanning electron microscopy illustrated that MWCNT-ZnO had better compatibility with MPBAT than with PBAT. At 0.2% MWCNT-ZnO, the MPBAT/MWCNT-ZnO nanocomposite film exhibited the greatest mechanical properties (17.74% increase in tensile strength, 22.17% in yield strength, and 14.29% in elongation at break). When the MWCNT-ZnO content was 0.4%, the nanocomposite film demonstrated the best water vapor barrier ability (an increase of 30.4%). The MPBAT/MWCNT-ZnO film with 0.6% MWCNT-ZnO turned out to have the best oxygen barrier performance (an increase of 130% relative to pure PBAT). It was shown from the results of antibacterial evaluation that the new nanomaterial could impart PBAT and MPBAT with antibacterial activity. The biodegradability tests indicated that an MWCNT-ZnO content of 0.2% could slightly reduce the biodegradability, and when the content was higher than 0.2%, the weight loss rate would increase.

Air-ozonolysis activation of polyolefins versus use of laden finishing to form contact-active nonwoven materials

Two synthetic approaches were explored for modification of the polyolefins polyethylene/polypropylene (PE/PP) to form contact-active nonwoven materials. In the first approach, polymer surfaces were activated by O2-free air-ozonolysis, and then the active agent (trimethoxysilyl) propyl-octadecyl-dimethyl-ammonium chloride (C18-TSA) was covalently bound. In the second approach, the active agent was directly conjugated to the commercial 'finishing' that was then applied to the polymer. The chemical, physical and microscopic properties of the modified polymers were comprehensively studied, and their active site density was quantified by fluorescein sodium salt-cetyltrimethylammonium chloride reaction. The antimicrobial activity of the prepared nonwovens against Bacillus subtilis (Gram-positive) and Salmonella enterica (Gram-negative), and their stability at various pHs and temperatures were examined. The two approaches conferred antimicrobial properties to the modified polymers and demonstrated stable linkage of C18-TSA. However, the performance of the nonwovens formed by the first approach was superior. The study suggests two feasible and safe pathways for the modification of polyolefins to form contact-active nonwoven materials that can be further applied in various fields, such as hygiene products, medical fabrics, sanitizing wipes, and more.

Characterization of network bonding created by intercalated functionalized graphene and polyvinyl alcohol in nanocomposite films for reinforced mechanical properties and barrier performance

Graphene that consists of less than 10 layers is expensive; moreover, it tends to agglomerate. These disadvantages restrict its utility. In this regard, the present study aimed to reduce the number of layers of a functionalized graphene (FG) with 10-30 layers to less than 10 layers by using an ultrasonic processor. We prepared nanocomposite films of polyvinyl alcohol (PVA) incorporated with FG by a simple hydrothermal method and ultrasonic dispersion. Oxygen transmission rate and water vapor permeability were considerably increased on account of modifying PVA with FG. Furthermore, the mechanical properties, thermostability, and barrier properties were improved. The barrier efficiency of the nanocomposites at different temperatures remained high for long periods of operation because of the network bonding. A simple procedure involving relatively low-cost nanomaterials could unlock the potential of nanocomposite FG/PVA films in the fields of coating, packaging, and semiconductor materials.

Effective Antibacterial Glass Fiber Membrane Prepared by Plasma-Enhanced Chemical Grafting

This paper reports a novel glass fiber membrane with an effective antibacterial performance by chemical grafting of quaternary ammonium salt (QAS) which is enhanced by a plasma bombardment technique. Plasma bombardment as a pretreatment of the membrane can increase the QAS anchored on the membrane from 0.8 to 1.3 wt %. The chemical grafting technique can increase the membrane zeta potential from negative values to positive values in aqueous solutions at various pHs. Furthermore, the plasma-enhanced chemical-grafting membrane has more positive zeta potentials (49.0 mV at pH = 7) than the chemical-grafting membrane without the plasma bombardment technique (38.9 mV at pH = 7). In the antibacterial performance evaluation, the Escherichia coli survival rate decreased from 127.0% of the pristine membrane to 4.1 and 11.3% of the plasma-enhanced chemical-grafting membrane and the chemical-grafting membrane, respectively. In addition, the plasma-enhanced chemical-grafting membrane shows durable antibacterial activity against E. coli with copious water rinsing as much as 3 L·cm-2.