Preparation And Properties Of Cellulose@Fe₃O₄ Composites

Petroleum based synthetic polymer materials bring seriously environmental problems during processing and under application.It is very important for us to study and develop sustainable,environmental-friendly polymer materials.It is feasible to choose natural sustainable polymer to replace some fossil based polymer step by step.As a result,the cellulose is choosen as the basic raw material in terms of renewable,biodegradable and the most widely available polymer on earth.The Cellulose@Fe3O4 composite is prepared based on the micro-nanostructure,in which the functional Fe3O4 nanoparticles(NPs)are in-situ formed on the surface of cellulose.Functional composites are designed based on as-prepared Cellulose@Fe3O4 composite.In the first part of the work,the reactive cores(Fe3O4 NPs)are anchored onto the cellulose chains by co-precipitation method.And the content and distribution of Fe3O4 NPs on surface of cellulose are easily regulated.Due to the additivity and cooperativity of hydrogen bonds as well as physical entanglement from cellulose chains,the biomass bulk materials(BCFCs)are prepared via in-situ formation of Fe3O4 NPs on the cellulose chains followed by hot-pressing without adhesion agent,leading to high density(1.7 g/cm3)magnetic medium,high compressive strength(CS)(213.6 MPa ±3.5 MPa)and excellent biodegradable property.This novel approach has a comprehensive effect on most of cellulose-based composites which indicates in-situ generating fillers are more efficient than blend fillers.This new strategy of biomass surface is not only suitable for cellulose powder,but also can be extended to other biomass materials.A series of green sustainable structural materials being prepared based on the new strategy.In the second part of the work,the Fe3O4,FeOOH and PB NPs are in-situ generated on the surface of cellulose by co-precipitation method,respectively.Three primary color composites(red Cellulose@Fe3O4,yellow Cellulose@FeOOH and blue Cellulose@PB)are prepared(the content of three primary color NPs is 10 wt%,respectively).The degree of saturation of the composites can be adjusted by regulating content of the three primary color nanoparticles on the surface of cellulose.Based on basic trichromatic principle,the three primary colors are independent,and any color can be mixed by three primary colors in different proportions.Arbitrary colors over the whole visible spectra can be prepared by mixing the three primary color composites at different ratios in the polymer field.To prove the universality of the coloring strategy,epoxy resin,polyvinyl acetate(PVAc)and polystyrene(PS)are selected as polymer matrix.Consequently,the prepared polymer composites have excellent UV absorption ability,durability and scalable colors,providing a new method in the polymer coloring field.In the third part of the work,the Fe3O4 NPs(10 wt%)are in-situ grown on the surface of cellulose by co-precipitation method.The lignin and Cellulose@Fe3O4 composites are quickly dissolved under alkali/urea/water system(-12℃).A novel Cellulose@Fe3O4/lignin-Ca2+hydrogel is prepared based on chemical and physical crosslinking networks by adding calcium ions and crosslinking agent(epichlorohydrin)into the formed homogeneous solution.The magnetic hydrogel displays excellent compressive strength(up to 300 kPa)and its elasticity is well-maintained under the temperature(-25～100 ℃).In addition,the magnetic hydrogel displays the outstanding fire resistance and UV absorption(100%)properties.Interestingly,the magnetic hydrogel exhibits controllable photoetching patterns based on the photothermal effect of Fe3O4 NPs under near-infrared(NIR)irradiation(808 nm),especially in the different circumstances including enclosed space and underwater condition.The photoetching magnetic cellulose-based hydrogel has great potential toward environmentally-friendly devices and applications in optics,electronics.In the fourth part of the work,drawing lessons from the third part of the work,the magnetic Cellulose@Fe3O4 hydrogel is prepared by adding the crosslinking agent(epichlorohydrin)in the alkali/urea/water system(-12℃).The self-thickening and self-strengthening hydrogel ink is achieved by regulating crosslinking time.The 3D printing of cellulose-based aerogel is achieved by direct ink writing with moderate rheology,and freezing drying.The magnetic cellulose-based aerogels are ideal adsorbers for adsorbing and removing organic pollutants from water.As catchers and carriers for magnetic removal,the Fe3O4 NPs of aerogel provide large active sites,where organic pollution enables fast and stable covalent binding on the surface.The adsorption effect of methylene blue(MB)is dependent on pH and the removal efficiency of MB(5.6 mg L-1,pH9)is 88.5%for magnetic aerogel,which occurs almost instantaneously at room temperature.In addition,the collected aerogel-MB hybrid can be reactivated by acid-washing(pH3),without significant changes in the adsorption performance of magnetic aerogel.The magnetic aerogel exhibits a fast,efficient and sustainable removal of organic pollutants,which provides an inexpensive and recyclable way for water remediation.