Sequence Regulation And Functionalization Of N-substituted Maleimide Derived Binary Copolymers

Natural biological macromolecules(DNA,proteins,etc.)have more excellent performance than synthetic polymers,mainly because the structure of natural polymers has higher stereoregularity,stricter unit sequence and functionalized groups.At present,it is still one of the most challenging tasks in the field of synthesis to maximize the development of innovative strategies to achieve controlled polymerization of polymer sequences,design and synthesize deviation sequence polymers with the same structural regularity as natural biological macromolecules The controllable sequence polymerization of N-substituted maleimide multicomponent copolymers is a research hotspot in the field of polymer sequence controllable polymerization.Based on the donor / acceptor monomer pairs that contain unsaturated double bonds chemically,with the similar or opposite polarities,and show different copolymerization tendencies,different strategies was used to achieve sequence control of three types of N-substituted maleimide binary copolymers In addition,by introducing different groups through molecular design to obtain functional heatresistant molecules,the structure-property relationship of its microscopic molecular structure and macroscopic thermal stability was studied.The paper work is summarized as follows:(?)A new heat-resistant modifier——sequence random N-phenylmaleimidemaleic anhydride binary copolymer(PNMA)was synthesized using Nphenylmaleimide(N-PMI)and maleic anhydride(MAH)as monomers at 80 ?-120 ? with 10? gradient by solution polymerization.The structure was characterized by nuclear magnetic resonance ~1H spectroscopy(~1H NMR)and Fourier transform infrared spectroscopy(FT-IR);the molecular weight and maleic anhydride content were quantitatively analyzed by gel permeation chromatography(GPC)and alkali titration;the thermal properties were analyzed by thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).The conclusions are as follows: by controlling the reaction temperature,the content of MAH monomer units,molecular weight and distribution of sequence random N-phenylmaleimide-maleic anhydride binary copolymer can be changed,thereby enabling effective regulation of its sequence structure;when the synthesis temperature is 110 ?,the sequence random binary copolymer has the highest content of MAH monomer units,the largest molecular weight,the most uniform molecular weight distribution,and the best thermal stability,which proves that 110 ? is most beneficial to the synthesis of sequence random Nphenylmaleimide-maleic anhydride binary copolymer.(?)A new heat-resistant modifier—sequence alternating N-(3-carboxy)phenylmaleimide-styrene binary copolymer(PTCS)was synthesized by free-radical copolymerization with N-(3-carboxyl)phenylmaleimide(3-CPMI)and styrene(St)as monomers.Its molecular structure is characterized by nuclear magnetic resonance spectroscopy(~1H,13C NMR)and Fourier transform infrared spectroscopy(FT-IR);the molecular weight distribution and N-(3-carboxy)phenylmaleimide content of the copolymer were quantitatively analyzed by gel permeation chromatography(GPC)and X-ray photoelectron spectroscopy(XPS);the thermal performance analysis was performed by thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC),and its thermal stability mechanism was analyzed by thermogravimetricinfrared combined spectroscopy(TG-FTIR).The results are as follows: the N-(3-carboxy)phenylmaleimide-styrene binary copolymer is a nearly stringent sequence alternating structure and shows good thermal stability,such as a higher glass transition Temperature(Tg? 229.7 ?)and a higher residual mass percentage(Yc? 46.2 %)at 650 ?,its thermal stability mechanism model is: with the continuous increase of temperature,dehydration reaction occurs between the molecular chains of the sequence alternating N-(3-carboxy)phenylmaleimide-styrene binary copolymer to form acid anhydride groups,which transforms the PTCS from a one-dimensional linear structure to a three-dimensional chemical cross-linked network structure.(?)A new heat-resistant modifier—sequence controllable N-phenylmaleimidestyrene binary copolymer synthesized(PNMS)by atom transfer radical copolymerization(ATRP)with N-phenylmaleimide(N-PMI)and styrene(St)as monomers..The localized addition of maleic anhydride-styrene copolymerized fragments in styrene long chains with a certain gradient distribution is achieved by the method of reversible deprotection of furan groups with temperature changes.Its molecular structure is characterized by dynamic nuclear magnetic resonance spectroscopy(~1H,13 C NMR)and Fourier transform infrared spectroscopy(FT-IR);Quantitative analysis of copolymer molecular weight distribution and N-(3-carboxy)phenylmaleimide content were realized by gel permeation chromatography(GPC)and X-ray photoelectron spectroscopy(XPS)respectively;its thermal performance analysis was performed by thermogravimetric analysis(TG)and differential scanning calorimetry(DSC).The results show that our experiment realizes the precise regulation of the sequence structure of PNMS through the accurate localization of the alternate copolymerization region of N-PMI and St in polymer chain,and the Nphenylmaleimide-styrene binary copolymer exhibit favourable thermal stability.