The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surfa...The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surface wrinkling precedes nucleation and crystal growth.This study examined the relationship between surface wrinkling,nucleation,and the formation of crystalline supramolecular structures using atomic force microscopy(AFM)and X-ray scattering measurements.Surface wrinkling is attributed to curving induced by accumulated stresses,including residual stress from the sample preparation and thermal stress during cooling.These stresses cause large-scale material flow and corresponding changes in the molecular conformations,potentially reducing the nucleation barrier.This hypothesis is supported by the rapid crystal growth observed following the spread of surface wrinkles.Additionally,the surface curving of the polymer thin film creates local minima of the free energy,facilitating nucleation.The nuclei subsequently grow into crystalline supramolecular structures by incorporating polymer molecules from the melt.This mechanism highlights the role of localized structural inhomogeneity in the early stages of crystallization and provides new insights into structure formation processes.展开更多
The structural changes around a crack tip in a high density polyethylene were investigated by means of scanning synchrotron microfocus small-angle X-ray scattering technique. The scattering data confirm the process of...The structural changes around a crack tip in a high density polyethylene were investigated by means of scanning synchrotron microfocus small-angle X-ray scattering technique. The scattering data confirm the process of craze structure development near a crack tip based on the evolution of voids. In addition, it was found that the main stress in the plastic zone near a crack tip exhibited a gradient distribution with respect to its strength and direction. The whole damaged area showed a strain distribution indicating a flow behavior toward the crack tip.展开更多
Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X...Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X-ray diffraction and proved that the crystallinity increased with the decrease of the mold size. This means that ordered nanostructures with atomic length scale order can be adjusted by tuning the mesoscale confinement. The inherent mechanism was the cooperation of geometric confinement, microphase structure and surface-induced ordering of PS-b-PCL in the melt, which paved the way for the subsequent crystal growth. These findings establish a route to promote the cost-effective nanofabrication by combining the mature microfabrication technique with the emerging directed self-assembly of block copolymers.展开更多
The development of power conversion efficiency(PCE)for organic solar cells(OSCs)based on polymer donors with benzo[1,2-b:4,5-b′]-difuran building block is slower than that of those based on benzodithiophene due to un...The development of power conversion efficiency(PCE)for organic solar cells(OSCs)based on polymer donors with benzo[1,2-b:4,5-b′]-difuran building block is slower than that of those based on benzodithiophene due to uncontrollable aggregation behavior.However,the former is expected to be more promising in realizing environmentally friendly and high-performance devices.Thereby,a smart aggregation tuning strategy is needed for boosting the efficiency of this type of OSCs.Here we report solid additives designed by self-imitation strategy,which aims to control the aggregation of the donor D18-Fu,and regulate the domain expansion of the acceptor L8-BO.Three oligomeric additives,with or without halogenation,can uniformly reduce the energy loss and enhance charge generation compared to an additive-free control device.This improvement is demonstrated through a series of morphological characterizations,photophysical analyses and theoretical simulations,indicating strong interaction between additive molecules and donor&acceptor.As a result,a 19%PCE is reported in binary OSCs,which also represents the highest level for devices based on benzo[1,2-b:4,5-b′]-difuran core contained polymer donor.Apart from high performance,our study provides new insights into manipulating the competition between the donor and acceptor's pure phase formation through new additive design methods.展开更多
基金the National Natural Science Foundation of China(Nos.U2032101 and 11905306)the National Key Research and Development Project of China(No.2022YFB2402602).
文摘The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surface wrinkling precedes nucleation and crystal growth.This study examined the relationship between surface wrinkling,nucleation,and the formation of crystalline supramolecular structures using atomic force microscopy(AFM)and X-ray scattering measurements.Surface wrinkling is attributed to curving induced by accumulated stresses,including residual stress from the sample preparation and thermal stress during cooling.These stresses cause large-scale material flow and corresponding changes in the molecular conformations,potentially reducing the nucleation barrier.This hypothesis is supported by the rapid crystal growth observed following the spread of surface wrinkles.Additionally,the surface curving of the polymer thin film creates local minima of the free energy,facilitating nucleation.The nuclei subsequently grow into crystalline supramolecular structures by incorporating polymer molecules from the melt.This mechanism highlights the role of localized structural inhomogeneity in the early stages of crystallization and provides new insights into structure formation processes.
基金supported by the"Hundred Talents Project"of the Chinese Academy of Sciences,the National Basic Research Program of China(No.2005CB623800)National Natural Science Foundation of China(Nos.50603024, 50621302) and HASYLAB projectⅡ-20052011
文摘The structural changes around a crack tip in a high density polyethylene were investigated by means of scanning synchrotron microfocus small-angle X-ray scattering technique. The scattering data confirm the process of craze structure development near a crack tip based on the evolution of voids. In addition, it was found that the main stress in the plastic zone near a crack tip exhibited a gradient distribution with respect to its strength and direction. The whole damaged area showed a strain distribution indicating a flow behavior toward the crack tip.
基金financially supported by the National Natural Science Foundation of China(Nos.21274148 and 21074135)The experimental setup at the Nanofocus Endstation of MiNaXS was funded by the German Federal Ministry of Education and Research(projects BMBF 05KS7FK1 and 05K10FK3)
文摘Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X-ray diffraction and proved that the crystallinity increased with the decrease of the mold size. This means that ordered nanostructures with atomic length scale order can be adjusted by tuning the mesoscale confinement. The inherent mechanism was the cooperation of geometric confinement, microphase structure and surface-induced ordering of PS-b-PCL in the melt, which paved the way for the subsequent crystal growth. These findings establish a route to promote the cost-effective nanofabrication by combining the mature microfabrication technique with the emerging directed self-assembly of block copolymers.
基金the support from the Poly U Distinguished Postdoc Fellowship(1-YW4C)the Guangdong Basic and Applied Basic Research Foundation(2025A1515012147)+8 种基金the National Natural Science Foundation of China(12404480,12274303)the Shenzhen Science and Technology Program(JCYJ20240813113238050,JCYJ20240813113306008)the Shenzhen Key Laboratory of Applied Technologies of Super-Diamond and Functional Crystals(ZDSYS20230626091303007)for the supportthe Guangdong S&T Program(2022B1212040001)the Guangdong-Hong Kong-Macao Joint Laboratory(2023B1212120003)for the supportthe Guangdong Government and the Guangzhou Government(2021QN02C110)the Guangzhou Municipal Science and Technology Project(2023A03J0097,2023A03J0003)the National Natural Science Foundation of China(NSFC)(52303249)for the supportfunding by the Federal Institute for Research on Building,Urban Affairs and Spatial Development on behalf of the Federal Ministry of the Interior,Building and Community with funds from the Zukunft Bau Research Program under grant“Nachhaltige Sonnenschutzsysteme aus hochfester Zellulose zur Umwandlung von Sonnenenergie”。
文摘The development of power conversion efficiency(PCE)for organic solar cells(OSCs)based on polymer donors with benzo[1,2-b:4,5-b′]-difuran building block is slower than that of those based on benzodithiophene due to uncontrollable aggregation behavior.However,the former is expected to be more promising in realizing environmentally friendly and high-performance devices.Thereby,a smart aggregation tuning strategy is needed for boosting the efficiency of this type of OSCs.Here we report solid additives designed by self-imitation strategy,which aims to control the aggregation of the donor D18-Fu,and regulate the domain expansion of the acceptor L8-BO.Three oligomeric additives,with or without halogenation,can uniformly reduce the energy loss and enhance charge generation compared to an additive-free control device.This improvement is demonstrated through a series of morphological characterizations,photophysical analyses and theoretical simulations,indicating strong interaction between additive molecules and donor&acceptor.As a result,a 19%PCE is reported in binary OSCs,which also represents the highest level for devices based on benzo[1,2-b:4,5-b′]-difuran core contained polymer donor.Apart from high performance,our study provides new insights into manipulating the competition between the donor and acceptor's pure phase formation through new additive design methods.
