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New Strategy For The Precise Synthesis Of Monodisperse Polymers Based On Thiol/Maleimide Chemistry And Its Application

Posted on:2021-05-04Degree:MasterType:Thesis
Country:ChinaCandidate:B L LiuFull Text:PDF
GTID:2381330605477077Subject:Chemistry
Abstract/Summary:PDF Full Text Request
As an ideal model for exploring the relationship between polymer structure and property,monodisperse polymers allow chemists to accurately understand,predict and tune the properties of polymer materials.Recently,monodisperse polymers have shown unique functions in the fields of materials and biological sciences.Whether monodisperse polymer can be synthesized depends on efficient organic chemical reactions and synthesis strategies(such as iterative stepwise growth and iterative exponential growth).Diverse and efficient chemical reactions can enrich the structural diversity of polymer chains.In addition,in this field,green,efficient,and mild precision polymer synthesis methods are important research issues with the purpose of constructing different types of functional polymers.In this paper,in view of this scientific problem,the following two aspects of work have been performed:(1)Based on the thiol-maleimide Michael "click" reaction,A new method with high efficiency,no metal catalysis and mild conditions for the precise synthesis of monodisperse polymers containing ester groups was developed,and the degradation properties of monodisperse polymers were initially explored;(2)With this efficient synthesis method,sequence-defined monodisperse polymer was constructed,which was adopted as digital polymer for efficient synthesis(information writing)and simple sequencing(information reading).The specific research is as follows:(1)Thiol-maleimide Michael addition is a green,highly efficient and metal-free "click" reaction.In this paper,bromine group was used as precursor group to produce thiol in the presence of thiourea and sodium metabisulfite,and a new synthetic method for monodisperse polymers was constructed in combination with the furan-maleimide reverse Diels-Alder reaction and the thiol-maleimide Michael addition reaction.Monodisperse polymer with repeat units up to 63 and a molecular weight of 17480.0 Da was efficiently synthesized via iterative exponential growth.The structural correctness and purity of a series of monodisperse polymers were validated by NMR,SEC and MALDI-TOF mass spectrometry.Compared with the previous work of our team,the new synthesis method is more mild and has better tolerance for most functional groups,making up for the inability to introduce acid-labile groups in the monomer.Besides,the degradation property of octamer and hexamer was demonstrated,clarifying the influence of molecular weight on the degradation performance.(2)Using the highly efficient synthesis route developed above,sequence-defined monodisperse polymer was further prepared,which was taken as molecular-level information storage carrier,namely,digital polymer,by combining with computer simulation to aid structural design.The digital polymer contains several factors conducive to tandem mass spectrometry(MS/MS)sequencing(information reading):First,one of the end groups in the digital polymer chain is bromine atoms which could be regarded as the sequencing tag due to its unique isotope distribution.Second,the ester groups in the repeating units enhance the binding ability with sodium ions and improve the signal intensity of the fragments.Third,the oxidation of succinimide sulfide to succinimide sulfoxide causes a significant reduction in bond dissociation energy,which can increase the selectivity of covalent bond cleavage in tandem mass spectrometry.Therefore,in this paper,two monomers containing alkyl chains of different lengths were firstly designed and synthesized,which were defined as 0-bit and 1-bit,respectively.Digital polymers were efficiently synthesized via iterative sequential growth.Subsequently,the sulfur atoms in the succinimide sulfide structure were oxidized to sulfoxide and sulfone,respectively,and they were sequenced by tandem mass spectrometry.The polymer containing sulfoxide structure showed clear and predictable MS/MS signals,which could be sequenced quickly and easily(information reading)with the help of bromine tag,and was a potentially promising digital polymer.
Keywords/Search Tags:monodisperse polymer, thiol-maleimide chemistry, digital polymer, tandem mass spectrometry, isotope tag
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