Synthesis Of Chitosan Carbon-based UV Absorber And Composite Phosphor And Its Application In Polymer Materials

Since the first discovery of carbon dots?CDs?in 2004,it has been widel y used in photocatalysis,ion detection,drug carriers and other fields due to its hydrophilicity,good photoluminescence and wide range of materials.With the continuous research of CDs,polymer carbon dots?PCDs?synthesized from non-conjugated linear polymers have attracted the attention of scholars.PCDs are carbon nano-dots formed by moderately cross-linked carbonization of carbon or assembled by carbon cores and polymers.They also have many excellent pro perties,such as low toxicity,good processability,low cost,etc.,and are easier to compare with CDs.It has the advantages of purification,retaining certain fu nctional groups of the polymer,and easy molecular modification.However,mo st of them currently apply PCDs directly to different fields,so it is important to design and synthesize new PCDs-based composite materials and study their application performance.In this paper,three kinds of chitosan,octanal,cinnamic acid,citric acid a nd 2,4-dihydroxy-benzophenone?UV-0?were synthesized by grafting,carbonizat ion and Mannich respectively.Chitosan derivative carbon-based UV absorber P?CS-g-OC?Ds-UV-0,P?CS-g-OC-CA?Ds-UV-0s and P?CS-g-CAL-CA?Ds-UV-0.The carbon dots of the chitosan derivative-based polymer were characterized by infrared spectroscopy,fluorescence spectroscopy,photoelectron spectroscopy?X PS?and transmission electron microscopy?TEM?.The characterization and prop erties of the polymer carbon-based UV absorber were studied by infrared spect roscopy,ultraviolet absorption spectroscopy and thermal decomposition?TGA?.The results showed that several UV absorbers were successfully prepared and h ave good performance in the range of 200-400 nm.UV absorption effect.The above-mentioned synthesized ultraviolet absorbers P?CS-g-OC?Ds-UV-0,P?CS-g-OC-CA?Ds-UV-0s and P?CS-g-CAL-CA?Ds-UV-0 was applied to woo d flour/PE composites respectively,and their UV-resistant aging properties were compared by UV accelerated aging,and compared with UV aging resistanceof UV absorbers.The impact strength and hardness test results of wood-plasticco mposites before and after UV aging indicate that the wood powder/PE wood-pl astic composite with P?CS-g-OC-CA?Ds-UV-0 added is better after 40 days of aging.Anti-UV aging effect.The cellulose index of wood-plastic composites aft er aging shows that P?CS-g-OC-CA?Ds-g-UV-0 and P?CS-g-CAL-CA?Ds-g-UV-0The ultraviolet absorber has an anti-ultraviolet aging effect superior to that of the parent UV-0.A composite phosphor?SiO₂/P?CS-g-CA?Ds?was prepared by combining c hitosan derivative polymer carbon dot P?CS-g-CA?Ds with nano-SiO₂,and the f luorescence spectrum and ultraviolet spectrum were obtained.The photolumines cence properties and UV absorption properties of SiO₂/P?CS-g-CA?Ds were test ed by means of CIE.The composite conditions of P?CS-g-CA?Ds and nano-Si O₂ were investigated.The results show that the optimal mass ratio of SiO₂ to P?CS-g-CA?Ds is 10:1,and the optimal composite pH is 4.The best SiO₂ mod el is the TSP-H10.Finally,an EVA-based SiO₂/P?CS-g-CA?Ds composite film was prepared by adding SiO₂/P?CS-g-CA?Ds to EVA by compression molding.The light conversion properties of the film were studied.The results show that the film has a good light conversion effect and can convert ultraviolet light i nto blue light which is beneficial to crop growth.