Lian Tang

Biomimetic mineralization synthesis of hydroxyapatite bacterial cellulose nanocomposites

Abstract Hydroxyapatite (HAp)/bacterial cellulose (BC) nanocomposites were prepared by an optimal biomimetic mineralization synthesis approach for bone tissue engineering application. BC with ultrafine three dimensional network was negatively charged by the adsorption of polyvinylpyrrolidone (PVP) to initiate the nucleation of HAp. The HAp was grown in vitro along the nanofiber network of BC via dynamic simulated body fluid (SBF) treatment. It was found that rod-like HAp particles in the nano-scale (100–200 nm) homogeneously deposited on the surface of PVP-BC. ATR-Fourier Transform Infrared Spectroscopy (ATR-FTIR) results showed that carbonate-containing HAp crystals resembling natural bones were formed by biomimetic mineralization method. Moreover, the amount of HAp observed increased with increasing mineralization time. And the Ca/P overall ratio ranged from 1.37 to 1.59. The results from Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) indicated that PVP treatment enhanced the apatite nucleation ability of BC with higher HAp deposit amount.

Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation.

Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe3O4 nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe3O4 nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit.

Flexible conductive polypyrrole nanocomposite membranes based on bacterial cellulose with amphiphobicity

Flexible conductive polypyrrole nanocomposite membranes based on bacterial cellulose (BC) with amphiphobicity have been successfully prepared through in situ chemical synthesis and then infiltrated with polysiloxane solution. The results suggested that polypyrrole (PPy) nanoparticles deposited on the surface of BC formed a continuous core-shell structure by taking along the BC template. After modification with polysiloxane, the surface characteristics of the conductive BC membranes changed from highly hydrophilic to hydrophobic. The AFM images revealed that the roughness of samples after polysiloxane treatment increased along with the increase of pyrrole concentration. The contact angles (CAs) data revealed that the highest water contact angle and highest oil contact angle are 160.3° and 136.7°, respectively. The conductivity of the amphiphobic membranes with excellent flexibility reached 0.32 S/cm and demonstrated a good electromagnetic shielding effectiveness with an SE of 15 dB which could be applied in electromagnetic shielding materials with self-cleaning properties. It opened a new field of potential applications of BC materials.

Effects of Poly(Ethylene Glycol) Segment on Physical and Chemical Properties of Poly(Ether Ester) Elastomers

Poly (ether ester) elastomer, a segmented copolymer, recently has attracted a wide attention for its unique properties such as elasticity, low temperature impact resistance and chemistry resistance. In this work, a range of poly (ether ester) s were synthesized via a two-step polymerization method using poly (ethylene terephthalate) (PET) as rigid segment and poly (ethylene glycol) (PEG) as flexible segment. The effects of the molecular weight (1000-8000 g/mol) and the weight ratios with PEG (30/100-70/100) of PET segments on the performance of synthetic copolymers were investigated. The chemical structure, thermal properties and hydrophilic performance of the copolymers were respectively characterized. Additionally, the practical block ratios of PEG/PET were calculated by the 1H-NMR Spectra of the copolymer after Soxhlet extraction. Through the obtained results, it revealed that increasing the molecular weight or content of PEG could enhance the hydrophilic performance of the copolymers and reversely reduce its thermal stability. It was shown that the reactivity of PEG in the polymerization process was weakened when its molecular weight was above 4000 or weight ratio with PTA was higher than 60/100, subsequently affected the practical block ratios of PEG/PET in the resulting poly(ether ester)elastomers.

Preparation and Characterization Flexible Conductive PPy/BC Nanocomposite Membrane

Polypyrrole (PPy) is an intrinsically conducting polymer that has a wide variety of potential applications on electrical devices, sensors, electrode material, anticorrosion and antistatic coatings. Bacterial cellulose (BC), a natural nano-material with outstanding properties, can be used as a template material. In this study, water-wet BC was firstly used to prepare PPy/BC nanocomposite membrane by combining with PPy. The obtained nanocomposite showed excellent performances such as high conductivity, considerable mechanicl behavior and perfect flexibility. Effects of pyrrole concentration and reaction time on the electrical conductivity of the membrane were investigated. Besides, FT-IR, FE-SEM and mechanical properties were studies. The results revealed that it was possible to develop a novel PPy/BC nanocomposite with potential applications on flexible displays or sensors.

Synthesis and Characterization of Bacterial Cellulose/Calcium Silicate Composites

A novel composites material consisting of calcium silicate deposited in bacterial cellulose membrane was synthesized by immersing BC membrane in the calcium and silicate solutions by turns with different cycle times and characterized. The results indicated that the CaSiO3 particles were homogeneously dispersed on the surface of nanofibers with the effect of BC template when two cycles of soaking proceed, during which the fabrication of most CaSiO3 particles took place. The FT-IR reveals the strong interaction between the two parts of the BC/CaSiO3 composite. The XRD pattern demonstrated a crystal structure disruption of the cellulose aroused by CaSiO3 particle. BC/ CaSiO3 is considered to have a potential application in bone tissue field.

Preparation of Nano Cu-ZnO/PET Fiber for Antibacterial Application

Polyethylene terephthalate (PET) fiber is applied to clothing, home textiles and other fields because of its low cost, high strength, quick-drying and stable structure, etc. Polyester fiber generally doesn’t have the ability to kill bacteria, and it is a kind of porous material which is conducive to the microbial adhesion and spread of bacteria. In the present study, Cu-ZnO and its antibacterial PET fibers were prepared by sol–gel method and melt spinning, respectively. The structures and compositions of Cu-ZnO were characterized by X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) spectra. The crystallization and melting behavior of the PET/Cu-ZnO (0.05:1) composites were tested by differential scanning calorimetry (DSC) to determine the temperate of melt spinning. The morphologies and mechanical properties of antibacterial polyester fiber were studied by field emission scanning electron micrographs (FE-SEM) and strength machine, respectively. The antibacterial properties of the samples on E. coli and S. aureus were determined using powder inhibition zones and antibacterial rate. The results show that the fibers exhibited excellent antibacterial activity, it had obvious inhibiting effects on E. coli and S. aureus and the antibacterial rate were both above 90%.

Preparation and Characterization of Antibacterial Nylon 6 Fiber

Due to its excellent mechanical property, dye ability and skin affinity, PA6 has been widely used in apparel, home textiles, military products, etc. However, PA6 fiber is easy to breed bacteria and corroded by bacteria in humid environment. One of development tendency of functional PA6 fiber is to design and develop nylon 6 fiber with excellent antibacterial properties, which is also the research target of this paper. In the present investigation, ZnO antibacterial agent was prepared through sol-gel method, and antibacterial masterbatch was acquired via blending antibacterial agent with PA6 using a twin-screw, then antibacterial PA6 fiber was obtained through melt spinning. The thermal properties, crystallization property of antibacterial PA6 masterbatch were discussed. The effect of drawing ratio on fiber strength, elongation of break, orientation and crystallization was also investigated. The antibacterial properties of antibacterial agent and antibacterial PA6 fiber was analyzed by agar diffusion method. The results of Differential Scanning Calorimetry (DSC) suggests that the antibacterial agent causes the rise of crystallization temperature and crystallization rate. X-Ray Diffraction (XRD) and mechanical testing results reveal that the higher drawing ratio leads to higher orientation and strength of PA6 fiber, lower elongation at break. The addition of antibacterial agent increases the degree of orientation and crystallization, reduces the strength of fiber and tends to form α crystalline in PA6 fiber. Antibacterial tests show that antibacterial PA6 fiber has a good antibacterial performance against Staphylococcus aureus.

Preparation and Properties of Cool-Feeling PA6 Fiber

In order to increase comfort of fabric, the development of fiber with the function of cool-feeling has been become the hotspot of chemical fiber industry. The cool-feeling fibers were prepared in this paper. The nano bowlder powder, aluminum nitride (AlN) powder, silicon carbide (SiC) powder were used as the cooling function powder, and the powders were modified by silane coupling agent 3-Aminopropyltriethoxysilane(KH-550). Nylon 6 (PA6) fibers with cooling function were prepared by melt blending method and melt spinning method. Further more, the properties of cool-feeling PA6 chip, fiber and fabric were characterized. The results show that the particle size of the powders become smaller and the distribution become narrower, the scale mainly distribute from 400 to 600 nm after the surface modification by KH-550. The results of thermal conductivity test and fabric contact cold test show that, the thermal conductivity of PA6 composite fiber reaches maximum with the value of 1.73 W/(m/K) when modified by AlN powder and bowlder powder. And the corresponding Q-max value of the fabric up to 0.162 J/cm2 s demonstrates that the cooling effect of composite fiber reach optimum.

Preparation and Properties of BC/PPy/TiO2 Composite Membrane

Bacterial cellulose (BC) /Polypyrrole (PPy) /TiO2 composite membrane was successfully prepared by in situ chemical oxidation polymerization of pyrrole in TiO2 sol into BC membrane matrix with different concentration of TiO2. The results of the field emission scanning electron microscopy observation revealed that the TiO2 nanoparticles coated with PPy were well homogeneously dispersed in the BC matrix. The photocatalytic activity of composite membrane was measured by methyl orange reaction model. Furthermore, the chemical structure of composite membrane and the anatase-TiO2 crystal structure were characterized by FT-IR spectroscopy and XRD analysis, respectively. According to this study, the photocatalytic activity of composite membranes was improved significantly by the addition of TiO2 due to the synergistic reaction between TiO2 and PPy. Besides that, the membrane exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to prepare the BC /PPy /TiO2 composite membrane which would have potential applications in wastewater treatment.