| Azobenzene functional polymer is a kind of polymer material with light-responsive activity,the reversible photoisomerization characterization and the resulting optical properties are hotspots of research,at the same time the azobenzene-polymer has good machinability and thermal stability,it has been widely concerned in optical components,optical switching and digital optical storage fields.As a substitute of polyaniline,aniline oligomer overcomes the default of insolubility,inmeltablity and poor processability,it also has well-defined molecular structure and electrochemical property similar with polyaniline,it is availible to adjust the the electrical conductivity by adjusting the length of aniline segment.Therefore the introducing of aniline oligomers into polymer structure as functional segments for preparation of electroactive polymer is a trend of the current study.In this article,through the molecular design and synthesis process optimization,three kinds of functional polymers containing both aniline oligomers and azo group are synthesized,which is respectively azo-aromatic ether?azo-PAE?,azo-aromatic esters?azo-PAR?andazo-polyamide?azo-PA?;moreover,thesyntheticpolymers'structures,photoisomerization performance,thermal stability,electrochemical property,conductivity and liquid crystallinity are characterized:?1?Through the nucleophilic substitution reaction,two kinds of difluorine amide monomers DFAD,DFAB were synthesized,of which one contained aniline dimer segment in the side chain and another contained azo group,then the monomers DFAD,DFAB and bisphenol-A were mixed as the 1:1:2 ratio for ternary nucleophilic copolymerization,finally the azo aromatic ether?azo-PAE?with aniline dimer in the side chain was synthesized.?2?3,3'-azobenzenediacidchloridewasmadetoreactwith4-hydroxyl-diphenylamine to prepare 3,3'-azobenzene-diester monomer ABDE with anilinegroups,thenthemonomer ABDEwasmadetoreactwith4-phenylene-diamine in the way of oxidative coupling polymerization,thus the azo aromatic ester?azo-PAR?with aniline tetramer in the main chain was synthesized.?3?3,3'-azobenzene diacid chloride and 3,3'-dichloro-4,4'-azobenzene diacid chloride were prepared respectively to react with N-phenyl-p-phenylenediamine in the way of nucleophilic substitution reaction,afterwards the azobenzene diamide monomers containing aniline groups ABDA,DCABDA were synthesized.By means of oxidative coupling polymerization,the monomers ABDA,DCABDA reacted respectively with p-phenylene-diamine to synthesize the azo polyamide?azo-PA?with aniline pentamer in the main chain.?4?By means of MS,FT-IR,1H NMR,melting point test,the synthetic monomers DFAD,DFAB,ABDE,ABDA,DCABDA's structures and melting points were characterized,the synthetic polymers'structures were characterized with FT-IR,1H NMR method.?5?By TG characterization,the thermal stability of synthetic polymer were analysized,the synthetic azo-PAE,azo-PAR and azo-PA?ABPA,DCABPA?had a weight loss of 5%,10%when the temperatures(Td5%/Td10%)got up to 280/345?,257/318?,237/336?and 257/318?respectively,when the temperature was800?,the polymers'decomposition rate were 52%,56%,53%and 56%;Solubility test showed that the side-chain azo-PAE had better solubility than the synthetic azo-PAR and azo-PA,which was not only soluble in strong polar solvents such as DMF,DMAc and NMP,but also partly dissolved in THF and acetone.?6?Irradiated under 365 nm UV hand lamp and then placed in dark place for a period of time,the synthetic polymers'DMAc solution showed the reversible cis-trans isomerization process in UV-vis spectrum;The synthetic polymers in oxidation state doped with HCl showed the generation of polarons as carriers,leading to the appearance of the conductive phase in polymer chain.Using AC impedance method on electrochemical workstation,the conductivities of three kinds of azo polymers powder pressed pellets were determined as 2.68×10-6,9.18×10-6,1.47×10-55 and 1.31×10-55 S/cm;Cyclic voltammogram curves of azo-PAE,azo-PAR and azo-PA showed 1,2,3 pairs of redox peaks respectively in scan voltage between-0.1 V-1 V,corresponding to the aniline oligomers in the polymer molecular chain transition between different oxidation states,which illustrated the synthetic polymers'similar electrochemical activity with that of polyaniline.?7?XRD spectrum showed that synthetic polymers had a poor crystallinity and belonged to the amorphous polymer kind;Being irradiated by orthogonal polarized light,POM pictures showed anisotropic liquid crystallinity of rodlike,fan,irregular polygon and oily textures liquid crystal form when the solution concentration of azo-PAE and azo-PAR in DMAC as well as azo-PA in NMP were higher than 3.6,2.5,4.1,3.9 mg/mL respectively..?8?By ReaxFF molecular dynamics simulation,the synthetic azo-PAE with aniline dimer in the side chain was pyrolytic simulated,which is to explore the ways initiating the decomposition of the polymer,along with the decomposition rates'change with simulated temperature,the quantity and the types of ultimate products of small molecules under different pyrolysis temperatures were also compared. |
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