As a renewable and environment-friendly technology for seawater desalination and wastewater purification,solar energy triggered steam generation is attractive to address the long-standing global water scarcity issues....As a renewable and environment-friendly technology for seawater desalination and wastewater purification,solar energy triggered steam generation is attractive to address the long-standing global water scarcity issues.However,practical utilization of solar energy for steam generation is severely restricted by the complex synthesis,low energy conversion efficiency,insufficient solar spectrum absorption and water extraction capability of state-of-the-art technologies.Here,for the first time,we report a facile strategy to realize hydrogen bond induced self-assembly of a polydopamine(PDA)@MXene microsphere photothermal layer for synergistically achieving wide-spectrum and highly efficient solar absorption capability(≈96%in a wide solar spectrum range of 250–1,500 nm wavelength).Moreover,such a system renders fast water transport and vapor escaping due to the intrinsically hydrophilic nature of both MXene and PDA,as well as the interspacing between core-shell microspheres.The solar-to-vapor conversion efficiencies under the solar illumination of 1 sun and 4 sun are as high as 85.2%and 93.6%,respectively.Besides,the PDA@MXene photothermal layer renders the system durable mechanical properties,allowing producing clean water from seawater with the salt rejection rate beyond 99%.Furthermore,stable light absorption performance can be achieved and well maintained due to the formation of ternary TiO2/C/MXene complex caused by oxidative degradation of MXene.Therefore,this work proposes an attractive MXene-assisted strategy for fabricating high performance photothermal composites for advanced solar-driven seawater desalination applications.展开更多
The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid)(PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid)(3A-PLLA) gra...The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid)(PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid)(3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the biodegradation performance. Different methods were used to characterize the structure of the grafted 3A-PLLA chains, the grafting density, and the thermal decomposition behavior of the nanoparticles. By varying the mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting densitytangled 3A-PLLA grafted SiO_2 was synthesized as "3A-PLLA grafting to SiO_2"(GTS), while low grafting density-stretched 3A-PLLA grafted SiO_2 was obtained as "SiO_2 grafting to 3A-PLLA"(GTA). Topology of nanoparticles as well as the filler-matrix interaction is critically important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM images showed the uniform dispersion of the modified nanoparticles, while the shear rheology results revealed that GTA nanoparticles made a more significant contribution on the melt-strengthening and relaxation time-extension of PLA. Moreover, it is suggested that GTA nanoparticles were more effective to act as a nucleating agent for PLA, which was proved by differential scanning calorimetry(DSC) and polarized optical microscopy(POM) researches. All of the improvements mentioned above of GTA nanocomposites can be ascribed to stronger entanglements between 3A-PLLA stretched by nano-SiO_2 and PLA matrix.展开更多
The hierarchical crystalline morphologies and orientation structures across the thickness direction in high-density polyethylene （HDPE） molded bars were investigated via a novel melt-penetrating processing method na...The hierarchical crystalline morphologies and orientation structures across the thickness direction in high-density polyethylene （HDPE） molded bars were investigated via a novel melt-penetrating processing method named multi-melt multi-injection molding （M3IM）. The samples with various mold temperatures （20, 40 and 60 ℃） were prepared, and the effects of the external temperature profile on the evolution of crystalline microstructures were studied. With scanning electron microscopy （SEM）, the transition of crystalline morphology from ring-banded structure to oriented lamellae was observed with decreasing mold temperature, and the oriented lamellae were formed at the sub-skin layer of the samples at the lowest mold temperature, which was further testified by differential scanning calorimetry （DSC）. With the decline of mold temperature, the degree of orientation, obtained from two-dimensional small angle X-ray scattering （2D-SAXS）, was increased and long periods rose a little. Thus, decreasing mold temperature was beneficial to the formation of orientation structures because the relaxation of chains was weakened.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51873126,51422305,and 51721091)。
文摘As a renewable and environment-friendly technology for seawater desalination and wastewater purification,solar energy triggered steam generation is attractive to address the long-standing global water scarcity issues.However,practical utilization of solar energy for steam generation is severely restricted by the complex synthesis,low energy conversion efficiency,insufficient solar spectrum absorption and water extraction capability of state-of-the-art technologies.Here,for the first time,we report a facile strategy to realize hydrogen bond induced self-assembly of a polydopamine(PDA)@MXene microsphere photothermal layer for synergistically achieving wide-spectrum and highly efficient solar absorption capability(≈96%in a wide solar spectrum range of 250–1,500 nm wavelength).Moreover,such a system renders fast water transport and vapor escaping due to the intrinsically hydrophilic nature of both MXene and PDA,as well as the interspacing between core-shell microspheres.The solar-to-vapor conversion efficiencies under the solar illumination of 1 sun and 4 sun are as high as 85.2%and 93.6%,respectively.Besides,the PDA@MXene photothermal layer renders the system durable mechanical properties,allowing producing clean water from seawater with the salt rejection rate beyond 99%.Furthermore,stable light absorption performance can be achieved and well maintained due to the formation of ternary TiO2/C/MXene complex caused by oxidative degradation of MXene.Therefore,this work proposes an attractive MXene-assisted strategy for fabricating high performance photothermal composites for advanced solar-driven seawater desalination applications.
基金financial support of the National Natural Science Foundation of China(Nos.51721091,21674069,and 21174092)
文摘The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid)(PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid)(3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the biodegradation performance. Different methods were used to characterize the structure of the grafted 3A-PLLA chains, the grafting density, and the thermal decomposition behavior of the nanoparticles. By varying the mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting densitytangled 3A-PLLA grafted SiO_2 was synthesized as "3A-PLLA grafting to SiO_2"(GTS), while low grafting density-stretched 3A-PLLA grafted SiO_2 was obtained as "SiO_2 grafting to 3A-PLLA"(GTA). Topology of nanoparticles as well as the filler-matrix interaction is critically important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM images showed the uniform dispersion of the modified nanoparticles, while the shear rheology results revealed that GTA nanoparticles made a more significant contribution on the melt-strengthening and relaxation time-extension of PLA. Moreover, it is suggested that GTA nanoparticles were more effective to act as a nucleating agent for PLA, which was proved by differential scanning calorimetry(DSC) and polarized optical microscopy(POM) researches. All of the improvements mentioned above of GTA nanocomposites can be ascribed to stronger entanglements between 3A-PLLA stretched by nano-SiO_2 and PLA matrix.
基金financially supported by the National Natural Science Foundation of China(Nos.21174092,51473105 and 51421061)the Major State Basic Research Development Program of China(973 program)(No.2012CB025902)
文摘The hierarchical crystalline morphologies and orientation structures across the thickness direction in high-density polyethylene （HDPE） molded bars were investigated via a novel melt-penetrating processing method named multi-melt multi-injection molding （M3IM）. The samples with various mold temperatures （20, 40 and 60 ℃） were prepared, and the effects of the external temperature profile on the evolution of crystalline microstructures were studied. With scanning electron microscopy （SEM）, the transition of crystalline morphology from ring-banded structure to oriented lamellae was observed with decreasing mold temperature, and the oriented lamellae were formed at the sub-skin layer of the samples at the lowest mold temperature, which was further testified by differential scanning calorimetry （DSC）. With the decline of mold temperature, the degree of orientation, obtained from two-dimensional small angle X-ray scattering （2D-SAXS）, was increased and long periods rose a little. Thus, decreasing mold temperature was beneficial to the formation of orientation structures because the relaxation of chains was weakened.
