In Situ Synthesis of Silver Nanoparticles on Amino-Grafted Polyacrylonitrile Fiber and Its Antibacterial Activity

Synthesis of sodium alginate grafted and silver nanoparticles filled anionic copolymer polyelectrolytes for adsorption and photocatalytic degradation of a cationic dye from water

Sodium alginate (SA) was grafted to poly (acrylonitrile-co‑sodium acrylate-co-acrylic acid). The grafted copolymer was crosslinked with N. N, methylene bis acrylamide (MBA). Silver nanoparticles (AgNPs) were generated in situ within the growing polymer network by reducing 0.1 mM silver nitrate with 0.05 mM ascorbic acid (ASA). The effect of initiator concentration, total monomer concentration, SA weight%, MBA weight% and acrylonitrile (AN):sodium acrylate (NaAA)/ acrylic acid (AA) molar ratios on the grafting were studied. The nanocomposite was characterized and used for adsorption of methylene blue (MB) dye from water. The composite was also used for photocatalytic degradation of the dye in the presence of sun light. The Box-Behnken design (BBD) of response surface methodology (RSM) with different compositions resulted in an optimized composition of 5:1 M ratio of AN:NaAA/AA, 1 wt% MBA and 2 wt% SA. The nanocomposite (SACP5Ag) prepared with the optimized composition showed an equilibrium batch adsorption(qe, mg/g)/removal(R)% of 245/98 from 50 mg/L MB dye in water and a qe /R% of 18.87/31.4 in a fixed bed adsorption at a feed inlet concentration(mgL-1)/inflow rate (mLmin-1)/bed height (mm) of 100/20/25. The composite showed a photocatalytic degradation efficiency of 98 % in sunlight for 80 min and a 1st order rate constant of 0.02 min-1.

In Situ Growth of Highly Compatible Cu2O-GO Hybrids Via Amino-Modification for Melt-Spun Efficient Antibacterial Polyamide 6 Fibers

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high-temperature melting environment. Cuprous oxide-loaded aminated grapheme (Cu2O-GO-NH2) is constructed by in situ growth method, and further PA6/Cu2O-GO-NH2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu2O-GO-NH2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu2O-GO fibers, the fracture strength of PA6/Cu2O-GO-NH2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu2O-GO-NH2 is 0.2 wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles.

Templating of catalytic gold and silver nanoparticles by waste plastic PET-derived hydrogel playing a dual role of a reductant and a matrix

The progressive accumulation of discarded plastic in the environment demands further development of waste management of plastic waste and conversion technologies of such waste to value-added materials. Recently, the conversion of plastic waste to functional materials via chemical recycling has attracted considerable attention. In this report, plastic waste (PET) was utilized for the preparation of a hydrogel-based catalyst via a cross-linking reaction of PET-derived oligo(terephthalamide)s followed by the electroless metallization. The polymeric matrix of PET-derived hydrogel plays multiple roles of (i) an adsorption media for noble metal ions such as Au³⁺ and Ag⁺, (ii) a reducing agent of Au³⁺ and Ag⁺ ions to Au⁰ and Ag⁰, and (iii) a matrix for the controlled growth of Au and Ag nanoparticles (AuNPs and AgNPs). The obtained hybrid hydrogels after metallization contained well-dispersed AuNPs and AgNPs of 6.1 ± 3.7 nm or 6.1 ± 1.4 nm size, respectively. The catalytic activities of the hybrid hydrogels with metal nanoparticles were studied in a model system of p-nitrophenol reduction in an aqueous solution. The hybrid materials of both Au@hydrogel and Ag@hydrogel were catalytically active for the reduction of p-nitrophenol, obeying the first-order kinetics. Importantly, the AuNPs or AgNPs in the hydrogel matrix preserved the original catalytic activity after multiple p-nitrophenol reduction reactions, showing a promising reusability of the catalysts. The proposed here approach aims to broaden the scope of conversion routes of plastic waste to value-added materials as well as to develop new types of polymeric matrices for templating and growth of metal nanoparticles for catalytic applications.

Environmentally Friendly and Broad-Spectrum Antibacterial Poly(hexamethylene guanidine)-Modified Polypropylene and Its Antifouling Application

Biological fouling is one of the main reasons that limits the application of traditional polypropylene (PP) fishing nets in aquaculture. Here, a new environmentally friendly and broad-spectrum antibacterial agent called cationic poly(hexamethylene guanidine) (PHMG) was grafted onto PP molecular chains via permanent chemical bonding to inhibit the biological fouling. The antibacterial monofilaments were obtained by blending different contents of PP-g-PHMG with PP by melt spinning. FTIR results found PHMG to be stably present in the mixed monofilaments after high-temperature melt spinning molding. The crystallinity, relaxation behavior, mechanical properties, water absorptivity, and antibacterial and antifouling efficiencies of the PP-g-PHMG/PP blends were strongly dependent on PP-g-PHMG. The crystallinity increased with increasing PP-g-PHMG content. Adding PP-g-PHMG improved the breaking strength, knotting strength, and elongation at the break for all ratios of PP-g-PHMG/PP blends. However, the water absorption caused by PHMG is low, ranging between 2.48% and 3.45% for the PP-g-PHMG/PP monofilaments. The monofilaments showed excellent nonleaching antimicrobial activities against Staphylococcus aureus and Escherichia coli. The electrostatic adsorption of the negatively charged bacteria and the destruction of their cell membrane allowed the growth inhibition to reach 99.69% with a PP-g-PHMG content of 40%. The marine fish farming experiment also showed a long-term antifouling effect.