Conjugated polymers are mainly synthesized by cross-coupling polymerizations catalyzed with transition metal(Pd,Ni)catalysts through step-growth polymerization(SGP)mechanism.According to the classical theory of SGP,th...Conjugated polymers are mainly synthesized by cross-coupling polymerizations catalyzed with transition metal(Pd,Ni)catalysts through step-growth polymerization(SGP)mechanism.According to the classical theory of SGP,the polymer dispersion index(D)of the synthesized polymers will never be higher than 2.However,the cases where conjugated polymers synthesized with D value far exceeding 2 are very common in reality,which severely limits their processing property,performance and applications.To investigate the reason behind the D value deviation from the theoretical value of SGP,direct arylation polycondensation(DArP)of 2-bromo-3-hexylthiophene(3HT)was chosen as the model reaction,and the reaction process was tracked using gel permeation chromatography analysis.When Pd(OAc)_(2) was used as the catalyst,the D value linearly increased with the increase of the weight-average molecular weight(M_(w))of polymer(P3HT)after a short period and reached up to 7.2 at prolonged reaction time.Scanning transmission electron microscopic images of the reaction mixture showed the fibril-like aggregation of P3HT and assembling of Pd species in P3HT aggregates.A catalyst competition mechanism was thus proposed,together with numerical calculation,giving a good fitting to the experimental results,which is believed to have far-reaching significance for guiding the design,synthesis and processing of conjugated polymers.展开更多
The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth poly...The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth polymerization of diols,carbonyl sulfide(CoS,or carbon disulfide,CS_(2)),and dichlorides.Diols and dichlorides are common chemicals,and CoS(CS_(2))is released as industrial waste.In addition to abun-dant feedstocks,the method is efficient and performed under mild conditions,using common organic bases as catalysts,and affording unprece-dented polymers.When cos,diols,and dihalides were used as monomers,optimized conditions could completely suppress the oxygen-sulfur exchange reaction,enabling the efficient synthesis of well-defined poly(monothiocarbonate)s with melting points ranging from 48°C to 101°C.These polymers,which have a structure similar to polyethylene with low-density in-chain polar groups,exhibit remarkable toughness and ductili-ty that rival those of high-density polyethylene(melting point:90°C,tensile strength:21.6±0.7 MPa,and elongation at break:576%).Moreover,the obtained poly(monothiocarbonate)s can be chemically degraded by alcoholysis to yield small-molecule diols and dithiols.When CS_(2)was used in place of cos,a pronounced oxygen-sulfur exchange reaction occurred.By optimizing reaction condition,it was found that polymers with-S(C=O)S-and-S(C=S)S-as the main repeating units exhibited high thermal stability and crystallinity.Thus,a new approach for regulat-ing the structure of polythiocarbonates via the oxygen-sulfur exchange reaction is developed.Overall,the polymers hold great potential for green materials due to their facile synthesis,readily available feedstocks,excellent performance,and chemical degradability.展开更多
The application of reversible degenerative radical polymerization(RDRP)in the construction of polymer networks(PNs)provides a facile and convenient way to fabricate 3D objects with the ability to be posttransformed.Ho...The application of reversible degenerative radical polymerization(RDRP)in the construction of polymer networks(PNs)provides a facile and convenient way to fabricate 3D objects with the ability to be posttransformed.However,the polymerization mechanism mainly relies on chain-growth polymerization,which limits its wide application for various polymeric materials with different functionalities.展开更多
Conjugated polymers are attractive components of modern plastic electronics and photovoltaic devices.They are synthesized mainly through a step-growth polymerization(SGP)mechanism.However,due to the uncontrollable cha...Conjugated polymers are attractive components of modern plastic electronics and photovoltaic devices.They are synthesized mainly through a step-growth polymerization(SGP)mechanism.However,due to the uncontrollable characteristic of classical SGP,this effort leads to batch-to-batch variations in solubility,uncontrolled molecular weight,and broad polydispersity of the polymers obtained,thus,severely limiting their processing properties and performance.Here we demonstrate a general theoretical model of controlled SGP process by examining the possibility of the polymer chains further involvement in the SGP and how this correlated with their respective molecular weights.Subsequently,we proposed a practical method by which the SGP system was confined in nano-sized reactors.This method enabled the synthesis of a variety of polymers,having precisely controlled molecular weights with narrow polydispersity.We anticipate that this venture would exemplify a starting point for a more sophisticated molecular and structural design of functional polymers in widespread applications.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(No.22171083)Shanghai Leading Academic Discipline Project(No.B502)。
文摘Conjugated polymers are mainly synthesized by cross-coupling polymerizations catalyzed with transition metal(Pd,Ni)catalysts through step-growth polymerization(SGP)mechanism.According to the classical theory of SGP,the polymer dispersion index(D)of the synthesized polymers will never be higher than 2.However,the cases where conjugated polymers synthesized with D value far exceeding 2 are very common in reality,which severely limits their processing property,performance and applications.To investigate the reason behind the D value deviation from the theoretical value of SGP,direct arylation polycondensation(DArP)of 2-bromo-3-hexylthiophene(3HT)was chosen as the model reaction,and the reaction process was tracked using gel permeation chromatography analysis.When Pd(OAc)_(2) was used as the catalyst,the D value linearly increased with the increase of the weight-average molecular weight(M_(w))of polymer(P3HT)after a short period and reached up to 7.2 at prolonged reaction time.Scanning transmission electron microscopic images of the reaction mixture showed the fibril-like aggregation of P3HT and assembling of Pd species in P3HT aggregates.A catalyst competition mechanism was thus proposed,together with numerical calculation,giving a good fitting to the experimental results,which is believed to have far-reaching significance for guiding the design,synthesis and processing of conjugated polymers.
基金supported by the National Natural Science Foundation of China(Nos.223B2119,U23A2083,52373014,52203129).
文摘The facile synthesis of high-valued polymers from waste molecules or low-cost common chemicals presents a significant challenge.Here,we develop a series of degradable poly(thiocarbonate)s from the new step-growth polymerization of diols,carbonyl sulfide(CoS,or carbon disulfide,CS_(2)),and dichlorides.Diols and dichlorides are common chemicals,and CoS(CS_(2))is released as industrial waste.In addition to abun-dant feedstocks,the method is efficient and performed under mild conditions,using common organic bases as catalysts,and affording unprece-dented polymers.When cos,diols,and dihalides were used as monomers,optimized conditions could completely suppress the oxygen-sulfur exchange reaction,enabling the efficient synthesis of well-defined poly(monothiocarbonate)s with melting points ranging from 48°C to 101°C.These polymers,which have a structure similar to polyethylene with low-density in-chain polar groups,exhibit remarkable toughness and ductili-ty that rival those of high-density polyethylene(melting point:90°C,tensile strength:21.6±0.7 MPa,and elongation at break:576%).Moreover,the obtained poly(monothiocarbonate)s can be chemically degraded by alcoholysis to yield small-molecule diols and dithiols.When CS_(2)was used in place of cos,a pronounced oxygen-sulfur exchange reaction occurred.By optimizing reaction condition,it was found that polymers with-S(C=O)S-and-S(C=S)S-as the main repeating units exhibited high thermal stability and crystallinity.Thus,a new approach for regulat-ing the structure of polythiocarbonates via the oxygen-sulfur exchange reaction is developed.Overall,the polymers hold great potential for green materials due to their facile synthesis,readily available feedstocks,excellent performance,and chemical degradability.
基金This work was supported by the National Natural Science Foundation of China(No.22101196)the China Postdoctoral Science Foundation(No.2021M692348)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions and the Program of Innovative Research Team of Soochow University.
文摘The application of reversible degenerative radical polymerization(RDRP)in the construction of polymer networks(PNs)provides a facile and convenient way to fabricate 3D objects with the ability to be posttransformed.However,the polymerization mechanism mainly relies on chain-growth polymerization,which limits its wide application for various polymeric materials with different functionalities.
基金the financial support from the National Natural Science Foundation of China(grant no.21674035 and 21604086)。
文摘Conjugated polymers are attractive components of modern plastic electronics and photovoltaic devices.They are synthesized mainly through a step-growth polymerization(SGP)mechanism.However,due to the uncontrollable characteristic of classical SGP,this effort leads to batch-to-batch variations in solubility,uncontrolled molecular weight,and broad polydispersity of the polymers obtained,thus,severely limiting their processing properties and performance.Here we demonstrate a general theoretical model of controlled SGP process by examining the possibility of the polymer chains further involvement in the SGP and how this correlated with their respective molecular weights.Subsequently,we proposed a practical method by which the SGP system was confined in nano-sized reactors.This method enabled the synthesis of a variety of polymers,having precisely controlled molecular weights with narrow polydispersity.We anticipate that this venture would exemplify a starting point for a more sophisticated molecular and structural design of functional polymers in widespread applications.
