Zhu Meifang

Antibacterial Nanofibers of Self-quaternized Block Copolymers of 4-Vinyl Pyridine and Pentachlorophenyl Acrylate

Well-defined antibacterial block copolymers of 4-vinyl pyridine (4VP) and pentachlorophenyl acrylate (PCPA) (P(4VP-b-PCPA)) were prepared via reversible addition—fragmentation chain transfer (RAFT) polymerization. Electrospinning of the P(4VP-b-PCPA) from a solution in mixed tetrahydrofuran and dimethylformamide gave rise to fibers with diameters in the range of 0.5—4.0 µm. The quaternary ammonium salts (QASs) were generated by N-alkylation of pyridine groups of P4VP block and chloro-aromatic compounds of PPCPA block (or self-quaternization of P(4VP-b-PCPA)). The self-quaternization of P(4VP-b-PCPA) nanofibers was studied by X-ray photoelectron spectroscopy. Attributable to the hydrophobicity of the PPCPA blocks and the electrostatic interaction of QASs generated from the self-quaternization of P(4VP-b-PCPA), the resulting nanofibers exhibit a high antibacterial efficiency. The antibacterial effect of the P(4VP-b-PCPA) nanofibers was assayed using Escherichia coli and Staphylococcus aureus cultures. It was found that 99.6% of E. coli and 99.1% S. aureus were killed after being in contact with 50 mg nanofibers in 10 min. The permanence of antibacterial activity of the self-quaternized P(4VP-b-PCPA) nanofibers was also demonstrated in repeat application.

Novel rapid response clay/poly(N-isopropylacrylamide) nanocomposite hydrogels by post treatment with HCl solution

Abstract A series of high clay content Laponite XLS/poly (N-isopropylacrylamide) (PNIPAAm) nanocomposite hydrogels (S-N gels) have been successfully prepared by in-situ ultraviolet (UV) initiated polymerization. The effects of post treatment with HCl solution on swelling/deswelling behaviour of the S-N gels have been investigated in detail. The results indicate that the Laponite XLS/PNIPAAm nanocomposite hydrogels with HCl solution post treatment (S-N-H gels) exhibit great swelling ratio and rapid deswelling response rate; much higher and faster than other reported clay/PNIPAAm nanocomposite hydrogels.

Research development of nano hybrid functional composite polyester fiber

Poly(ethylene terephthalate) (PET) is one of the most extensively used semicrystal polymers, which has found its applications in fibers, films, packaging and molding materials. About 80% of polyester products is polyester fiber and polyester fiber is the largestvariety of chemical fiber, but its industrial development is limited by severe homogeneousness, unitary function, inferior functionalization ratio, high cost and low added value. Due to good machinability and excellent mechanical properties of poly(ethylene terephthalate) fiber, a common method to realize the functionalization of PET fiber is introducing nano-materials into the PET matrix based on organic/inorganic hybrid principle. This paper summarizes the research status of PET matrix nano-hybrid functional fibers with flame-retardant, antibacterial, uvioresistant and conductive properties, including the preparation methods, modification ways, fabrication techniques and functional performances of these fibers. Also, this paper evaluates the merits of three modification methods: surface coating, blending and in situ polymerization; furthermore investigates the effect of blending and in situ polymerization on the dispersion of nano materials and the spinnability of nano composites. Finally, this paper prospects the developing direction of PET matrix nano-hybrid functional fibers: structural and functional design of nanomaterials, controllable interface of nano-materials and polyester, post-finishing technology of nano-hybrid materials; develop multifunctional, intelligent and environment-friendly nano hybrid industrial fibers, and set up systemic evaluation standards of ecological safety of nano-hybrid fiber.

Preparation and optimization of Polyvinylidene fluoride (PVDF) triboelectric nanogenerator via electrospinning

With more and more wearable electronics entering the market, the bottleneck of batteries attracts considerable attentions because of its limited lifetime and energy storage capacity. To solve this problem, triboelectric nanogenerators (TENG) have recently been researched to be applied on harvesting mechanical energy from ambient environment, which is of great significance in the field of energy conversion. In this paper, Electrospinning is introduced to prepare all-fiber mats for its significant advantages such as simple, low-cost and versatile. A range of polymer electrospun mats are assembled as the positive triboelectric materials with the electronegative material, Polyvinylidene fluoride (PVDF), to fabricate TENGs. Furthermore the energy transform of TENG is optimized when adjusting the experiment parameters systematically, such as the mats thickness, nanofibers morphology, high-aligned mats friction angle of mat-based TENG and environmental humidity. It is a significant progress to research the influence factors of TENG for fabricating self-powered device via electrospinning.

Enhanced output power polyvinylidene fluoride (PVDF) electrospun nanogenerator with high fiber alignment

High-aligned PVDF nanofiber mats-based nanogenerators are prepared via electrospinning using a high-speed rolling collector without any post-poling treatment. The effect of alignment on ß phase composition and output voltage of the different alignment samples are investigated. The anisotropic of output voltage based on the fiber alignment and bending direction (the fiber aligned direction, marked as 0°) is first reported. Under the bending direction of 0°, the maximum generated piezo-voltage exhibited by aligned PVDF nanofiber mats is as high as 9 V, increases of 350% compared to random mats with no significant change on crystallinity and ß phase content. It is verified that the alignment degree of nanofibers plays an important role in the effect of energy transformation. Interestingly, a remarkable enhancement in mechanical property has also been achieved and one can expect the nanogenerator with high alignment has the higher output in wide applications.

Organic-inorganic hybrid material and multifunctional fibers

Organic-inorganic hybrid materials can achieve the multi-scale composites of organic polymers and inorganic materials in the nano or molecular level. On one hand, such hybrid materials can exert each components characteristics. On the other hand, they reflect the unique collaboration features, such as new performance and multifunction. This principle can also be implemented in organic-organic hybrid system. With the continuous development of industrial fiber materials, their applications continue to be expanded. The development of new polymer materials to achieve multifunctional fibers has become a hot topic. According to the requirement of multifunctional fibers development, researchers try to build hybrid functional materials at the molecular level, build hybrid functional materials system and fiber-forming polymer hybrid system using the methods of structural design and construct interface combining with the organic-inorganic hybrid mechanism. This paper takes the structural design and condensed control of fiber-forming polymers, the structure-controllable preparation of nano-fibers and low-dimensional nano-fibers for example, introducing the research progress of organic-inorganic hybrid principles in the aspect of multi-functional fibers. Finally, it prospects the development of multifunctional organic-inorganic hybrid fibers.