Block copolymers(BCPs) with high Flory-Huggins parameter(χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns processing.However,high χ and balanced surface energy are general...Block copolymers(BCPs) with high Flory-Huggins parameter(χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns processing.However,high χ and balanced surface energy are generally contradicted.The fine tune of chain structure might be a useful way to achieve high χ and balanced surface energy.To realize this,the block copolymer with exactly uniform chain structure,i.e.,defined molecular structure,is highly desirable for accurately evaluating the phase behavior.Herein,two kinds of discrete oligo ester-b-oligo olefin block copolymers with different chemical structures(oligo lactic acid-boligo olefin BCP,oLA_(n)-b-C_(m);oligo phenyl lactic acid-b-oligo olefin BCP,oPL_(n)-b-C_(m)) were modularly synthesized through iterative growth methods.The effect of chain structure on segregation strength and surface properties was quantitatively investigated using the discrete BCPs as precise models.On the one hand,introducing rigid and nonpolar phenyl groups into oligo ester block has a negligible effect on the chemical incompatibility,as confirmed by the identical high χ values of oLA_(n)-b-C_(m) and oPL_(n)-b-C_(m)(χ_(oLA/C)=0.21 and χ_(oPL/C)=0.19).On the other hand,the incorporation of nonpolar phenyl groups creates balanced surface energy,that is,the high χ and balanced surface energy were simultaneously achieved by oPL_(n)-b-C_(m).Therefore,sub-10 nm perpendicular nanopatterns can be easily produced upon brief thermal treatment,demonstrating its potential application in semiconductor manufacturing with ultra-small feature size.The discrete BCP can serve as a quantitative and exquisite model to study the critical contribution of chain structures on phase separation behavior,providing insightful understanding to facilitate the potential application in the chip process.展开更多
The inherent uncertainty of chain length in synthetic polymers casts doubt on the explicit understanding of fundamental principles.This study quantitatively assesses the critical role of chain-length distribution in t...The inherent uncertainty of chain length in synthetic polymers casts doubt on the explicit understanding of fundamental principles.This study quantitatively assesses the critical role of chain-length distribution in the self-assembly process,aiming to identify the point at which discernible discrepancies begin to emerge.By blending discrete diblock copolymers of varying sizes,chain-length nonuniformity can be precisely regulated while the average composition remains constant.Introducing a minor heterogeneity leads to an expansion of lattice dimension,while a phase transition occurs as the difference exceeds a threshold.Interestingly,a transition from the Frank–Kasperσphase to the body-centered cubic phase was triggered by enlarging the size difference of the corona block,while introducing heterogeneity in the core block stabilized the hexagonally close-packed spheres.A self-consistent field theory calculation reveals that the synergy between the long and short chains effectively releases packing frustration,leading to substantial changes in the free-energy landscape and stabilizing unconventional phases otherwise inaccessible.This work calls particular attention to the importance of chain-length heterogeneity and provides a robust approach to finely tuning the phase behavior and physical properties of block copolymers without altering their chemical composition.展开更多
＂Click chemistry＂ is, by definition, a general functionalization methodology （GFM） and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis. This paper repor...＂Click chemistry＂ is, by definition, a general functionalization methodology （GFM） and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis. This paper reports the synthesis of a ＂clickable＂ middle-chain azide-functionalized polystyrene （mPS-N3） by anionic polymerization and its application in the preparation of novel shape amphiphiles based on polyhedral oligomeric silsesquioxane （POSS）. The mPS-N3 was synthesized by coupling living poly（styryl）lithium chains （PSLi） with 3-chloropropylmethyldichlorosilane and subsequent nucleophilic substitution of the chloro group in the presence of sodium azide. Excess PSLi was end-capped with ethylene oxide to facilitate its removal by flash chromatography. The raPS-N3 was then derived into a giant lipid-like shape amphiphile in two steps following a sequential ＂click＂ strategy. The copper（I）-catalyzed azide-alkyne cycloaddition between mPS-N3 and alkyne-functionalized vinyl-substituted POSS derivative （VPOSS-alkyne） ensured quantitative ligation to give polystyrene with VPOSS tethered at the middle of the chain （mPS-VPOSS）. The thiol-ene reaction with 1-thioglycerol transforms the vinyl groups on the POSS periphery to hydroxyls, resulting in an amphiphilic shape amphiphile, mPS-DPOSS. This synthetic approach is highly efficient and modular. It demonstrates the ＂click＂ philosophy of facile complex molecule construction from a library of simple building blocks and also suggests that mPS-N3 can be used as a versatile ＂clickable＂ motif in polymer science for the precise synthesis of complex macromolecules.展开更多
Objective To search for the potential medicinal plant part of Gentiana macrophyllabased on changes of secondary metabolites and trace elements in the flowers of G.macrophylla.Methods HPLC was used to detect the change...Objective To search for the potential medicinal plant part of Gentiana macrophyllabased on changes of secondary metabolites and trace elements in the flowers of G.macrophylla.Methods HPLC was used to detect the changes of the active constituents（longanic acid,sweroside,gentiopicroside,and swertiamarin）and ICP-AES was used for mineral nutrients in G.macrophylla during flower development.And soluble sugar,starch,crude protein,hemicelluloses,cellulose,and lignin were determined.Results Biomass of flower in full bloom（D2）phase was considerable during flower development,in which the contents of longanic acid and gentiopicroside were at the highest levels with 2.65 and 2.88 times higher than those recorded in Chinese Pharmacopoeia 2010,sweroside and swertiamarin in the flowers were reaching 6.06 and 1.25 times higher than those in roots.Florescence is the most valuable stage during flower development.The concentration of Fe,Mg,K,P,and B was higher in the flowers than that in roots.The accumulation of active constituents in the plant was influenced by the contents of metabolically linked carbon and nitrogen compounds.Conclusion The secondary metabolites,mineral nutrients,and physicochemical indicators are tightly regulated by flower organ development,D2 is an important stage for both biomass and extraction of active constituents such as longanic acid.The flowers of G.macrophylla could be used as a potential medicinal plant part for longanic acid at a high level.展开更多
This mini review summarizes recent progress on two-dimensional(2 D) self-assembly of giant molecules. Two critical factors with significant impact on the formation of nanostructure are highlighted, i.e., the dimension...This mini review summarizes recent progress on two-dimensional(2 D) self-assembly of giant molecules. Two critical factors with significant impact on the formation of nanostructure are highlighted, i.e., the dimensional constraint of 2 D geometry, and the conformational constraint imposed the rigid molecular nanoparticles(MNPs). Diverse 2 D nanostructures have been fabricated in condensed state and solution by rational molecular design. The collective secondary interactions between functional groups on the periphery of the MNPs and their persistent shape, together with the dimensional limit, change the free energy landscape and lead to unconventional nanostructures. The unique molecular properties of giant molecules endow these 2 D structures with promising technological applications.展开更多
基金supported by the National Natural Science Foundation of China(21925107,22273026)China Postdoctoral Science Foundation(71st,2022M712306)+1 种基金the Collaborative Innovation Center of Suzhou Nano Science and Technologythe Jiangsu Funding Program for Excellent Postdoctoral Talent。
文摘Block copolymers(BCPs) with high Flory-Huggins parameter(χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns processing.However,high χ and balanced surface energy are generally contradicted.The fine tune of chain structure might be a useful way to achieve high χ and balanced surface energy.To realize this,the block copolymer with exactly uniform chain structure,i.e.,defined molecular structure,is highly desirable for accurately evaluating the phase behavior.Herein,two kinds of discrete oligo ester-b-oligo olefin block copolymers with different chemical structures(oligo lactic acid-boligo olefin BCP,oLA_(n)-b-C_(m);oligo phenyl lactic acid-b-oligo olefin BCP,oPL_(n)-b-C_(m)) were modularly synthesized through iterative growth methods.The effect of chain structure on segregation strength and surface properties was quantitatively investigated using the discrete BCPs as precise models.On the one hand,introducing rigid and nonpolar phenyl groups into oligo ester block has a negligible effect on the chemical incompatibility,as confirmed by the identical high χ values of oLA_(n)-b-C_(m) and oPL_(n)-b-C_(m)(χ_(oLA/C)=0.21 and χ_(oPL/C)=0.19).On the other hand,the incorporation of nonpolar phenyl groups creates balanced surface energy,that is,the high χ and balanced surface energy were simultaneously achieved by oPL_(n)-b-C_(m).Therefore,sub-10 nm perpendicular nanopatterns can be easily produced upon brief thermal treatment,demonstrating its potential application in semiconductor manufacturing with ultra-small feature size.The discrete BCP can serve as a quantitative and exquisite model to study the critical contribution of chain structures on phase separation behavior,providing insightful understanding to facilitate the potential application in the chip process.
基金supported by the National Natural Science Foundation of China(grant no.22273026)the Recruitment Program of Guangdong(grant no.2016ZT06C322)+1 种基金the Research Funds from State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials,Soochow University(grant no.SDGC2109)the 111 Project(grant no.B18023).
文摘The inherent uncertainty of chain length in synthetic polymers casts doubt on the explicit understanding of fundamental principles.This study quantitatively assesses the critical role of chain-length distribution in the self-assembly process,aiming to identify the point at which discernible discrepancies begin to emerge.By blending discrete diblock copolymers of varying sizes,chain-length nonuniformity can be precisely regulated while the average composition remains constant.Introducing a minor heterogeneity leads to an expansion of lattice dimension,while a phase transition occurs as the difference exceeds a threshold.Interestingly,a transition from the Frank–Kasperσphase to the body-centered cubic phase was triggered by enlarging the size difference of the corona block,while introducing heterogeneity in the core block stabilized the hexagonally close-packed spheres.A self-consistent field theory calculation reveals that the synergy between the long and short chains effectively releases packing frustration,leading to substantial changes in the free-energy landscape and stabilizing unconventional phases otherwise inaccessible.This work calls particular attention to the importance of chain-length heterogeneity and provides a robust approach to finely tuning the phase behavior and physical properties of block copolymers without altering their chemical composition.
文摘＂Click chemistry＂ is, by definition, a general functionalization methodology （GFM） and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis. This paper reports the synthesis of a ＂clickable＂ middle-chain azide-functionalized polystyrene （mPS-N3） by anionic polymerization and its application in the preparation of novel shape amphiphiles based on polyhedral oligomeric silsesquioxane （POSS）. The mPS-N3 was synthesized by coupling living poly（styryl）lithium chains （PSLi） with 3-chloropropylmethyldichlorosilane and subsequent nucleophilic substitution of the chloro group in the presence of sodium azide. Excess PSLi was end-capped with ethylene oxide to facilitate its removal by flash chromatography. The raPS-N3 was then derived into a giant lipid-like shape amphiphile in two steps following a sequential ＂click＂ strategy. The copper（I）-catalyzed azide-alkyne cycloaddition between mPS-N3 and alkyne-functionalized vinyl-substituted POSS derivative （VPOSS-alkyne） ensured quantitative ligation to give polystyrene with VPOSS tethered at the middle of the chain （mPS-VPOSS）. The thiol-ene reaction with 1-thioglycerol transforms the vinyl groups on the POSS periphery to hydroxyls, resulting in an amphiphilic shape amphiphile, mPS-DPOSS. This synthetic approach is highly efficient and modular. It demonstrates the ＂click＂ philosophy of facile complex molecule construction from a library of simple building blocks and also suggests that mPS-N3 can be used as a versatile ＂clickable＂ motif in polymer science for the precise synthesis of complex macromolecules.
基金Major National Science and Technology Program(2009ZX09308)
文摘Objective To search for the potential medicinal plant part of Gentiana macrophyllabased on changes of secondary metabolites and trace elements in the flowers of G.macrophylla.Methods HPLC was used to detect the changes of the active constituents（longanic acid,sweroside,gentiopicroside,and swertiamarin）and ICP-AES was used for mineral nutrients in G.macrophylla during flower development.And soluble sugar,starch,crude protein,hemicelluloses,cellulose,and lignin were determined.Results Biomass of flower in full bloom（D2）phase was considerable during flower development,in which the contents of longanic acid and gentiopicroside were at the highest levels with 2.65 and 2.88 times higher than those recorded in Chinese Pharmacopoeia 2010,sweroside and swertiamarin in the flowers were reaching 6.06 and 1.25 times higher than those in roots.Florescence is the most valuable stage during flower development.The concentration of Fe,Mg,K,P,and B was higher in the flowers than that in roots.The accumulation of active constituents in the plant was influenced by the contents of metabolically linked carbon and nitrogen compounds.Conclusion The secondary metabolites,mineral nutrients,and physicochemical indicators are tightly regulated by flower organ development,D2 is an important stage for both biomass and extraction of active constituents such as longanic acid.The flowers of G.macrophylla could be used as a potential medicinal plant part for longanic acid at a high level.
基金supported by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams (2016ZT06C322)the Fundamental Research Funds for the Central University (2017JQ006)the National Natural Science Foundation of China (51773066)
文摘This mini review summarizes recent progress on two-dimensional(2 D) self-assembly of giant molecules. Two critical factors with significant impact on the formation of nanostructure are highlighted, i.e., the dimensional constraint of 2 D geometry, and the conformational constraint imposed the rigid molecular nanoparticles(MNPs). Diverse 2 D nanostructures have been fabricated in condensed state and solution by rational molecular design. The collective secondary interactions between functional groups on the periphery of the MNPs and their persistent shape, together with the dimensional limit, change the free energy landscape and lead to unconventional nanostructures. The unique molecular properties of giant molecules endow these 2 D structures with promising technological applications.
