Study On The Structures And Properties Of Polyarylene Ether Nitrile Metal Complexes And Their Hybrids

Polymer metal complexes are a class of materials with both polymer and metal characteristics,which have attracted extensive attention from scholars in the domains of polymer chemistry,supramolecular chemistry,organometallic chemistry,catalysis,sensing,energy,environment,biomedicine,etc.Incorporating metals into polymers can endow polymers with diverse physicochemical properties and facilitate the expansion of their application fields.At the same time,robust molecular design and controllable polymerization technology can precisely confine metals on the polymeric frameworks,thereby presenting functional properties differing from those of small-molecule metal complexes.However,it is difficult for the polymer metal complexes to meet the design requirements of both micro/nanoscale materials and macroscopic materials.On the other hand,the current polymer metal complexes generally suffer from fewer varieties of compositions and functions.Especially the involved polymers are often limited by chemical stability and thermal stability,the categories of which are in urgent need of expansion.As a type of super-engineering polymer,polyarylene ether nitrile possesses excellent thermal stability,chemical stability,and high freedom of structural designability,which has the potential to become an ideal matrix for novel polymer metal complexes.Therefore,in this dissertation,the super-engineering polymer namely polyarylene ether nitrile is selected as the polymeric skeleton,and the combination with the specific metallic component is enhanced through the molecular structure design in advance.The polyarylene ether nitrile metal complex materials with microscopic and macroscopic structures are respectively obtained,whose corresponding functionalization fields are further explored.The main contents of this dissertation are as follows:1.In view of the excellent chemical stability and structural designability of polyarylene ether nitrile,polyarylene ether nitrile copolymers containing various functionalized side groups were designed and synthesized,and the complexation between various functional groups and Fe³⁺was used to achieve the confined growth of Fe₃O₄nanocrystals,and magnetic polyarylene ether nitrile metal complex nanoparticles were prepared in a one-pot procedure.The polyarylene ether nitrile was able to strongly complex with Fe₃O₄ and anchor on the surface of magnetic nanoparticles with the assistance of side groups,thus changing the surface chemical properties of magnetic nanoparticles.The obtained polyarylene ether nitrile metal complexes retained the inherent magnetic loss properties of Fe₃O₄,enhanced the dielectric loss mechanisms of magnetic nanoparticles,as well as improved their attenuation abilities and impedance matching properties for incident electromagnetic waves,which showed potential applications in the field of microwave absorption.2.To address the shortage of high filling amounts of single magnetic nanoparticles,the functionalized reduced graphene oxide nanosheets were introduced as a hybrid component using the surface chemical properties of polyarylene ether nitrile metal complex nanoparticles,and the magnetic nanoparticles were loaded on graphene nanosheets via electrostatic interactions and extensiveπ-conjugation interactions to obtain polyarylene ether nitrile metal complex hybrids with two-dimensional structures.The obtained two-dimensional structured hybrids exhibit excellent magnetic responsiveness and can be rapidly collected by applying an external magnetic field at the end of their preparation,simplifying the preparation process of microwave absorption materials.The tunable microwave absorption performances are achieved at a low level of filling amount,especially at a very low thickness（≤1.5 mm）with both good reflection loss（-43.1 d B）and effective absorption bandwidth（4.3 GHz）,showing excellent ultra-thin microwave absorption properties.3.To further improve the microwave absorption performances of the hybrids,Mo S₂nanoflowers and reduced graphene oxide nanosheets were introduced as binary hybrid components to modify the polyarylene ether nitrile metal complex nanoparticles simultaneously,and multiple interfacial interactions were employed to realize the interfacial coupling of multiple magnetic/dielectric components,resulting in the polyarylene ether nitrile metal complex hybrids with three-dimensional interconnected framework structures.The sequential introduction of the hybrid components facilitates the formation of the internal porous structure and endows the hybrids with excellent impedance matching properties and magnetoelectric coupling effect,thus increasing the reflection loss of the hybrids to-57.8 d B while the filling amount remains unchanged.Further optimization of the microwave absorption performances can be triggered by adjusting the graphene nanosheet contents to achieve a good balance between low thickness,strong absorption,and wide bandwidth,and the results of radar cross section simulation also confirm the excellent microwave absorption capabilities of the hybrids.4.Considering the advantages of macroscopic properties of polyarylene ether nitrile,copper phthalocyanine,an aromatic macrocyclic metal complex,was introduced into the molecular structure of polyarylene ether nitrile,and the covalent coupling between copper phthalocyanine and polyarylene ether nitrile was utilized to prepare the macroscale polyarylene ether nitrile metal complex films.The kinetic analysis of the thermal decomposition of the polyarylene ether nitrile metal complex films was carried out using the Flynn-Wall-Ozawa method,and the results showed that the crosslinking effect of multi-functionalized copper phthalocyanine on linear polyarylene ether nitrile could limit the high-temperature creep and delay the thermal decomposition behavior of polyarylene ether nitrile.Meanwhile,the high dielectric responsiveness of copper phthalocyanine can not only act as polarization centers to enhance the dielectric constant but also promote the formation of the crosslinked network to suppress the leakage current under the external electric field and reduce the dielectric loss,which provides a feasible strategy for the design of dielectric films.5.To further optimize the thermal stability and dielectric properties of the films,barium titanate nanoparticles were introduced as the hybrid component.The copper phthalocyanine was pre-modified on the surface of the nanoparticles for uniform dispersion in the polyarylene ether nitrile matrix,and then the interfacial transition layer was formed by the covalent bonding between the functionalized shell layer and the matrix,finally obtaining the polyarylene ether nitrile metal complex hybrid films.The thermal decomposition properties and kinetic models of the polyarylene ether nitrile metal complex hybrid films were investigated via both Kissinger and Flynn-Wall-Ozawa methods,and the thermal aging lifespans of the hybrid films were predicted,which confirmed the successive enhancement of the thermal stabilities of the films by the introduction of nano-barium titanate and the formation of polyarylene ether nitrile metal complex.Compared with simple blending,the uniform dispersion of high-k ceramic nanoparticles and the construction of polyarylene ether nitrile metal complex transition layer can improve the overall polarization strength of the films while moderating the dielectric difference,homogenizing the electric field distortion,and suppressing the formation of inter-particle leakage current,thus achieving the synergistic enhancements of dielectric constant and breakdown strength.The super-engineering polymer,polyarylene ether nitrile,was investigated in this dissertation,and Fe₃O₄ and copper phthalocyanine were selected as metal units to respectively construct microscopic polyarylene ether nitrile metal complex nanoparticles and macroscopic polyarylene ether nitrile metal complex films,and the hybrid components were subsequently introduced to optimize the performances of polyarylene ether nitrile metal complexes in their corresponding application fields.The obtained series of polyarylene ether nitrile metal complexes and their hybrids expand the structural properties of polymer metal complexes from microscopic to macroscopic scales,enrich the design strategies and application fields of polymer metal complexes,and provide new approaches for the design of multi-scale functional polymer materials.