Preparation Of New Functional Polymers Containing 9,9-Diphenyl Xanthene Groups Via Multicomponent And Click Polymerization

It is of great significance and potential value to develop fast and efficient polymerization methods for the preparation of macromolecules with novel structure and unique functions.However,most traditional polymerization reactions such as condensation,coupling and ring opening polymerization reactions based on one or two components,which are used in the construction of complex and multi-functional polymers,have many shortcomings such as involving multi-step reaction with complex post-processing;or monomers need to be pre-activated or harsh polymerization conditions;or using not readily available monomers,or proding harmful by-products,etc.In recent years,click polymerizations(CPs),multicomponent polymerizations(MCPs) and (multicomponent tandem polymerizations,MCTPs) based on click chemistry,multicomponent reactions(MCRs)and multicomponent tandem reactions(MCTRs)of small organic molecules,provide new methodologies for rapid and efficient construction of functional polymers with unique structure.Based on the rich reactivity of alkynes,as well as the advantages of constructing functional polymers via CPs,MCPs and MCTPs,the corresponding polymerizations of terminal diynes containing 9,9-diphenylxanthene structure for the preparation of functional polymers have been investigated.The main contents of the paper are described as follow:Part one:Through combination of Sonogashira coupling-Michael addition-cyclocondensation reactions in a one-pot procedure,an efficient three-component tandem polymerization of terminal diynes such as 9,9-bis(4-ethynylphenyl)xanthene(BEPX),9,9-bis(3-methyl-4-ethynylphenyl)xanthene(BEMPX)and 9,9-bis[4-(prop-2-ynyloxy)phenyl]xanthene(BPYPX),terephthaloyl chloride(TPC),hydrazine hydrate or phenylhydrazine was proceed smoothly under mild conditions at room temperature afforded a series of novel polypyrazoles bearing 9,9-diphenylxanthene moieties in the main chains with high molecular weights(M_w up to 17300 g/mol)in excellent yields(up to 94%),respectively.These amorphous polypyrazoles generally enjoy good solubility and film-forming ability,high thermal stability(the temperature of 5%weight loss is between 223 and 343 ~oC),high transmittance.Among them,the polypyrazole containing N-phenyl side groups showed better performance.Part two:Similarly,five new polypyrazoles containing 9,9-diphenylxanthene and N-phenyl groups in the main chains with high molecular weights(M_w up to 17400g/mol)were prepared from three-component tandem polymerization of BEPX,phenylhydrazine,and five aromatic diacid chlorides such as isophthaloyl dichloride,1,4-naphthalene diacid chloride,4,4'-biphenyl diacid chloride,1,3-bis(4-chloroformyl-phenoxy)benzene and 2,2-bis[4-(4-chloroformylphenoxy)phenyl]hexafluoropropane were prepared under mild conditions.The resulting functional polymers have good solubility in most non-proton polar solvents such as N,N-dimethylformamide tetrahydrofuran and pyridine at room temperature and film-forming ability high thermal stability,high transmittance.Among them,the introduction of flexible groups such as ether bond and trifluoromethyl could improve the solubility and transmittance,but decrease the thermal stability to a certain extent.Part three:In the presence of copper(I)chloride,the three-component polycoupling reactions of BEPX,n-butylamine,and aromatic aldehydes such as4-methylbenzaldehyde,4-methoxybenzaldehyde,4-chlorobenzaldehyde,4-bromoben-zaldehyde,4-nitrobenzaldehyde and 4-trifluoromethylbenzaldehyde was carried out in toluene at 100°C for 6 h to afford regular poly(dipropargyl amine)s(PDAs)containing 9,9-diphenylxanthene moieties in the main chains with high molecular weights(M_w up to 16400 g/mol)in good yields(85–91%).The polymerization reaction is insensitive to moisture,The new functional PDAs are amorphous and thermally stable(the temperature of 5%weight loss is between 198 and 226 ~oC),and show good solubility in most organic solvents and film-forming property,and have good optical transparency.Part four:The hydroxamoyl chloride as a precursor of the nitrile N-oxide was first prepared by condensation of terephthalaldehyde or isophthalaldehyde with hydroxylamine hydrochloride,followed by treatment with N-chlorosuccinimide(NCS).Then,the click polymerization via 1,3-dipolar cycloaddition reaction of the diynes as above and nitrile N-oxide in situ by the reaction of the corresponding hydroxamoyl chloride with molecular sieves 4?efficiently produced polyisoxazoles bearing 9,9-diphenylxanthene moieties in the main chain in good yields(80–85%).The resulting polyisoxazoles agree well with the structural assignment obtained by the NMR analysis.Although the molecular weights of the resulting polymers are not very large,having narrow molecular weight distribution(M_w/M_n=1.08–1.17).Their structures are regular,and show certain crystallization properties and good thermal stability(the temperature of 5%weight loss is between 128 and 355~oC),as well as excellent solubility and transmittance.In addition,introduction of flexible ether linkage in the main chain can significantly reduce the crystallinity,and the corresponding polymers showed amorphous characteristics.