Construction Of Co-intercalated Layered Double Hydroxides And Enhancement For The Performance Of Polymer

Polymer materials with excellent characteristics such as light weight,low cost and easy processing have been widely used in the fields of automobiles,household appliances and electronics,and occupy an important position in the national economy.The performance of polymer materials is mainly controlled by the functional additives,and the efficiency are closely related to the chemical composition,structure and dispersion in the polymer materix.For example,low-molecular weight anti-aging agents are easy to volatilize and migrate out of PP matrix during processing or the service life,which does not only decrease the efficiency of antiaging but also leads to the pollution of environment.In addition,photoluminescence materials are also faced with some problem,such as aggregation-caused quenching(ACQ),poor thermal stability and environmental pollution.Therefore,the design and assembly of migrationresistant anti-aging agents and high-dispersion luminescent materials with orderly structure and adjustable performance are of great significance for the development of novel multifunctional materials.Recently,some interesting multifunctional materials have been explored by the co-intercalation of different active species into the interlayer region of layered double hydroxides(LDH),and they exhibited more excellent application performance related to the corresponding active species themselves due to the synergistic effect between the active species and the LDH host.This thesis aims at the design and fabrication of migration-resistant anti-aging agents and high-dispersion luminescent materials.LDH are used as the host part,and the functional materials with anti-aging or fluorescent properties are used as the guests.A series of inorganic-organic multifunctional materials were prepared through the co-intercalation assembly method.The anti-aging and luminescent performance were carefully investigated by adjusting the composition of LDH,species and concentration of interlayer molecules.Futhermore,to improve the dispersion degree of LDH particles in the polymer matrix,the relationship between the compatibility and the performance enhancement of inorganic fillers and polymer has been studied.The main contents and results are shown as follows:(1)Low-molecular-weight hindered phenolic antioxidants(M and D)and hindered amine light stabilizer(H)were intercalated into the galleries of LDH by co-precipitation method to prepare a series of inorganic-organic anti-aging agents,adjusting the composition of LDH and anion ratio.The LDH/PP composites were prepared by solvent mixing method.The series co-intercalated HxMy-LDH and HxDy-LDH exhibit higher thermal stability compared to that of H(M,D)-LDH,the decomposition temperature of H1M2-LDH and H1D1-LDH increased by nearly 50?.There is a strong chain extension effect on PP for HxDy-LDH,with an interfacial interaction being largely developed through solvent mixing and an improvement in mechanical properties.Morever,the HxDy-LDH series present much higher enhancement on the thermal aging of PP.It emphasizes that the co-intercalation structure and the ratio of HxDy in the interlayer both show the beneficial effect of preventing the thermal aging of PP,in a synergistic way.(2)Based on the spatial confinement effect of LDH,the photoactive organic molecules(PAO)and quantum dots(QD)are introduced into the galleries of different LDH as a second guest in very small quantities.The presence of anti-aging agents and bola molecules in LDH-(AO or UV)/PAO and QD-bola-LDH are expected to prevent the aggregation of PAO and QD as well as to provide them a suitable environment for enhancing luminescent performances.Their optical properties are studied upon blue-UV excitation and the luminescent films could be applied in LED lighting.For each LDH-(AO or UV)/PAO,an optimal concentration to give the higher PLQYab is depicted.AO and UV as spacers with aromatic rings are basically harmless to the luminescent of PAO.It can be noticed that the samples with HPTS,C343 or RhB can be excited efficiently by UV or blue commercial LED.Besides,for the assembly of InP/ZnS QD and bola-LDH,the expansion of the basal spacing from 6.47 to 6.92 nm is subsequent to the re-arrangement of the interleaved bola anions to accommodate QD.The ssPLQY of QD-bola-LDH is 18%,which is about 3 times higher than pristine QD.The QD-bola-LDH silicone film shows brighter and more homogeneously-distributed luminescence.The film is used for LED light to compensate for the lack of yellow phosphor,and the hotometric parameters reach CT=3576 K and CRI=93.8.The dispersion of the LDH fillers endows the silicone composite with luminescent properties close to optical properties of the pristine hybrid materials.(3)Regarding the difficulty of dispersing inorganic nano-functional additives in polymer systems,the aqueous miscible organic(AMO)and exfoliation method have been adopted for the previous intercalated antioxidant.The LDH/PP composites were prepared by solvent mixing method.In the process of AMO treatment,the intercalation structure effectively inhibits the migration of the guest D.The anti-aging performance is gradually improved as the AMO time is 9 h and then is reduced.D-LDH(6h)/PP represent the lowest migration in the series.Besides,D-LDH was delaminated into well-dispersed monolayers in xylene to form a sol and the exfoliated nanosheets possess excellent radical scavenging capability.The protection time of exfoliated DLDH/PP is about 14 h longer than that of mixed D-LDH/PP,only 30.4%of D leached out from the exfoliated LDH/PP films after 132 h test.The exfoliated D-LDH didn't restacked to ordered structure in the PP matrix and it is nucleation activity are among the high level.Both AMO and exfoliation treatment effectively improve the dispersion of LDH in the polymer matrix,The increased compatibility with polymers and exposed active ingredients were enhance the thermal aging of composites.