The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micr...The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.展开更多
Thermal cycle training of CuZnAl shape memory alloys with differenttransformation temperatures was carried out. The influence of different pre-strains, heat treatmentsand media on the shape memory effect(SME) of CuZnA...Thermal cycle training of CuZnAl shape memory alloys with differenttransformation temperatures was carried out. The influence of different pre-strains, heat treatmentsand media on the shape memory effect(SME) of CuZnAl alloys with different transformationtemperatures was studied by means of scanning electron microscopy(SEM) and X-raydiffractometry(XRD). Experimental results show that despite respective variation in heat treatment,medium and cycling number, the recover}'' rate always decreases as pre-strain increases. The declineis obvious when pre-strain is less than 2.6 percent but not so sharp when pre-strain exceeds 2.6percent. Larger pre-strain results in more than one slip system and causes intercutting of themartensite strips among martensitic variants, then leads to the decline of SME. The SME of alloyswith transformation temperatures below 347 K is larger than that of alloys beyond 361 K by 20percent - 40 percent. The recovery rate of two-step aged alloy is higher than that of step-quenchedalloy by 20 percent - 25 percent. During thermal cycling, the recovery rate in oil is better thanthat in water.展开更多
Molecular imprinting of proteins remains a huge chal-lenge because of two major obstacles:difficulty in template removal and low imprinting efficiency.Herein,we propose a new strategy to simultaneously overcome these ...Molecular imprinting of proteins remains a huge chal-lenge because of two major obstacles:difficulty in template removal and low imprinting efficiency.Herein,we propose a new strategy to simultaneously overcome these two challenges by creating molecu-larly imprinted polymers(MIPs)with nanoscale shape-memorable imprint cavities.These novel MIPs were developed by simply cross-linking the polymers with a peptide cross-linker instead of commonly used cross-linkers.Due to the unique pH-induced helix–coil transition of the peptide cross-linker,adjusting the pH from 5.5 to 7.4 leads to an expansion of the imprint cavities,thus facilitating template removal.Returning the pH back to 5.5 restores the original size and shape of the imprint cavities due to the precise refolding of peptide.A template protein can there-fore be readily removed under mild conditions,while simultaneously achieving a significantly improved imprinting effect.展开更多
基金X.G. and Z.X. contributed equally to this work. Y.Z. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11502129 and 11722217） and the Tsinghua National Laboratory for Information Science and Technology. Y.H. acknowledges the support from the NSF （Grant Nos. CMMI1400169, CMMI1534120 and CMMI1635443）. X.G. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11702155）.
文摘The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.
基金Project(BE2004027) supported by the Science and Technology Foundation of Jiangsu Province,China
文摘Thermal cycle training of CuZnAl shape memory alloys with differenttransformation temperatures was carried out. The influence of different pre-strains, heat treatmentsand media on the shape memory effect(SME) of CuZnAl alloys with different transformationtemperatures was studied by means of scanning electron microscopy(SEM) and X-raydiffractometry(XRD). Experimental results show that despite respective variation in heat treatment,medium and cycling number, the recover}'' rate always decreases as pre-strain increases. The declineis obvious when pre-strain is less than 2.6 percent but not so sharp when pre-strain exceeds 2.6percent. Larger pre-strain results in more than one slip system and causes intercutting of themartensite strips among martensitic variants, then leads to the decline of SME. The SME of alloyswith transformation temperatures below 347 K is larger than that of alloys beyond 361 K by 20percent - 40 percent. The recovery rate of two-step aged alloy is higher than that of step-quenchedalloy by 20 percent - 25 percent. During thermal cycling, the recovery rate in oil is better thanthat in water.
基金This work was funded by the National Natural Science Foundation of China(grant nos:51625302 and 51873091)the National Key Research and Development Program of China(2017YFC1103501).
文摘Molecular imprinting of proteins remains a huge chal-lenge because of two major obstacles:difficulty in template removal and low imprinting efficiency.Herein,we propose a new strategy to simultaneously overcome these two challenges by creating molecu-larly imprinted polymers(MIPs)with nanoscale shape-memorable imprint cavities.These novel MIPs were developed by simply cross-linking the polymers with a peptide cross-linker instead of commonly used cross-linkers.Due to the unique pH-induced helix–coil transition of the peptide cross-linker,adjusting the pH from 5.5 to 7.4 leads to an expansion of the imprint cavities,thus facilitating template removal.Returning the pH back to 5.5 restores the original size and shape of the imprint cavities due to the precise refolding of peptide.A template protein can there-fore be readily removed under mild conditions,while simultaneously achieving a significantly improved imprinting effect.
