Preparation And Properties Of Bacterial Cellulose-based Functional Materials

Cellulose aerogel with the advantages of both green regenerated cellulose material and porous aerogel material is a third-generation aerogel material independent of inorganic aerogel materials and organic polymer aerogel materials.It could be used as the catalysts,adsorbent materials,thermal insulation materials,super capacitors,and particle detection,etc.Based on the fact that cellulose is a hydrophilic biopolymer and the hydroxyl groups on the molecular chains of cellulose have chemically active properties.The hydrophobicity and mechanical properties of cellulose aerogels could be improved by using physical or chemical modification means.The introduction of electrical,magnetic,biological activity and other functionalities would further expand the application of cellulose aerogels.In this the research,the bacterial cellulose composites containing functional groups was successfully prepared by using electron transfer for atom transfer radical polymerization(ARGET ATRP)polymerization method which were as follows.The bacterial cellulose aerogels were prepared by alkali-boiled purification and vacuum freeze-drying method.The porosity of aerogels was determined by ethanol adsorption,and the structure and properties of bacterial cellulose aerogels were characterized by comparison surface apparatus(BET),Scanning electron microscope(SEM),infrared spectroscopy(FI-IR)and X-ray diffraction(XRD).The results showed that the BC aerogels were successfully prepared by freeze-drying,and the aerogel had three-dimensional reticular structure,the fiber diameter was 30~50nm,the fiber distribution was uniform,the porosity of BC aerogels was 98.24%,the density was 0.012g/cm3,and the specific surface area was 138.572m2/g.The regular graft copolymers,BC-g-PGMA was synthesized via electron transfer for atom transfer radical polymerization(ARGET ATRP),using bacterial cellulose aerogels with bromide side-group(BC-Br)as the macroinitiator and N,N,N',N,'N"-pentamethyldiethylenetriamine(PMDETA)/copper(II)bromide(CuBr2)as catalytic system,vitamin C as reducing agent and Glycidyl methacrylate(GMA)as the comonomer.Spectroscopy(EDS)macroinitiators element content was determined,and by using infrared spectroscopy(FT-IR),X-ray diffraction(XRD),scanning electron microscope(SEM),thermo-gravimetric analysis(TGA)on the structure and properties have been characterized.The results indicate that the control grafting polymerization of GMA on BC aerogels,the molecular weight distribution was 1.07,macroinitiators Br elements can reach to 6.77%,fiber diameter increased after GMA graft polymerization and formed in the fiber surface layer,the thermal stability increased from 205? to 246?.The catalase was immobilized on the BC-g-PGMA copolymer with epoxy resin as the carrier.The effects of temperature and pH on the activity of enzyme and the activity of enzyme during immobilization of enzymes were studied.The optimum pH and temperature of free catalase and immobilized catalase were discussed.And the thermal stability and repeated use of immobilized enzymes were investigated by using infrared spectroscopy(FI-IR),The structure and morphology of immobilized catalase were analyzed by scanning electron microscope(SEM).The results showed that the optimum temperature and pH of immobilization were 35? and 6.0.The maximum enzyme content was up to 116.72mg/g at this optimum condition.The durability of pH and temperature and storage stability were improved after immobilization,and the immobilized enzyme had good reuse performance.BC-g-PDMAEMA was synthesized via electron transfer for atom transfer radical polymerization(ARGET ATRP),using bacterial cellulose aerogels with bromide side-group(BC-Br)as the macroinitiator and N,N,N',N,'N"-pentamethyldiethylenetriamine(PMDETA)/copper(?)bromide(CuBr2)as catalytic system,vitamin C as reducing agent and 2-(dimethylamino)ethyl methacrylate(DMAEMA)as the comonomer.Then with bromine ethane as functional modification reagent,to quaternary ammonium,BC aerogel preparation has antibacterial properties of grafted polymer.Molecular weight distribution,Element content,chemical structure,thermal stability,crystalline structure and surface morphology of the modified BC aerogels were characterized by GPC,EDS,FT-IR,TGA,XRD and SEM.The results indicate that the BC-g-PDMAEMA polymers were successfully prepared by ARGET ATRP.The molecular weight distribution was 1.05 and the grafting rate of DMAEMA is 875.76%.After grafting,the diameter of the fiber was increased and the covering layer was formed on the fiber surface.The thermal stability of the BC-g-PDMAEMA polymers increased from 205 ? to 230?.After quaternary ammonium BC-g-PDMAEMA graft copolymer,the inhibitory ring is obvious,the maximum can reach 10mm,the antibacterial effect is good.