Subcritical CO2 Assisted Polymer Surface Engineering at Low Temperatures

2004 ◽  
Vol 843 ◽  
Author(s):  
Yong Yang ◽  
Ly James Lee
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Surface Engineering ◽  
Polymer Surface ◽  
Three Dimensional ◽  
Polymer Processing ◽  
Polymer Surfaces ◽  
Surface Dynamics ◽  
Chain Mobility ◽  
Bonding Technique

ABSTRACTPolymer-based Micro/Nano Electro Mechanical Systems (MEMS/NEMS) have attracted a great deal of interest from industries and academia. The common polymer processing methods involve either organic solvents or temperatures above the glass transition temperature (Tg), which is undesirable, particularly for biomedical applications. On the basis of different properties near polymer surfaces from those in the bulk, we introduce subcritical fluids (particularly carbon dioxide, CO2) into polymer surfaces to manipulate the polymer properties at the nanoscale so that we can achieve low temperature surface engineering. In this study, polymer surface dynamics under CO2 were addressed using atomic force microscopy (AFM) and neutron reflectivity (NR). Monodispersed nanoparticles were deposited onto the smooth polymer surface and then embedded into the surface by annealing the sample at the pre-specified temperatures and CO2 pressures. The embedding of nanoparticles in the proximity of the surface was measured using AFM, and thus the surface Tg profile could be determined. It was revealed that there is a rubbery layer of up to a hundred nanometers thick at the surface where the Tg is lower than that in the bulk and CO2 dramatically reduced the surface Tg. NR studies also show that CO2 can enhance chain mobility at the polymer surfaces below the polymer bulk Tg. These results indicated that even low concentrated CO2 greatly could enhance polymer chain mobility below the Tg of the CO2–plasticized polymers. The thickness of the rubbery layer can be controlled by tuning either temperatures, or CO2 pressures, or both, which makes it possible to engineer polymer surfaces at low temperatures. Guided by the CO2 enhanced polymer surface dynamics, we developed a novel CO2 bonding technique to succeed in low temperature bonding of polymers at the micro/nanoscales. This CO2 bonding technique has been applied to seal polymeric nanofluidic biochips and construct well-defined three-dimensional (3D) biodegradable polymeric tissue scaffolds.

Low-temperature solid-state growth of three-dimensional bicontinuous nanoporous graphene with tunable porosity for lithium–sulfur batteries

2018 ◽  
Vol 6 (24) ◽  
pp. 11405-11415 ◽  
Author(s):  
L. Q. Lu ◽  
N. Schriever ◽  
J. Th. M. De Hosson ◽  
Y. T. Pei
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Lithium Sulfur Batteries ◽  
Nanoporous Graphene ◽  
State Growth ◽  
Growth Approach ◽  
Lithium Sulfur

In this work we developed a solid-state-growth approach for the synthesis of 3D interconnected bicontinuous nanoporous graphene (NPG) with the aid of nanoporous Ni templates at low temperatures (below 800 °C).

Digital X-Ray Flat Panel Housing for Operation at Extremely Low Temperatures

2019 ◽  
Vol 942 ◽  
pp. 68-76
Author(s):  
Fedor Simankin ◽  
Jan Miciński ◽  
Evgeniy Shumnyi ◽  
Alexander Shtein ◽  
Ablay Zhunusov
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Wall Structure ◽  
Flat Panel ◽  
Three Dimensional Printing ◽  
X Ray ◽  
Temperature Conditions ◽  
Dimensional Printing

The paper presents the housing wall structure for the digital X-ray flat panel which can operate in extremely low temperature conditions. A technology of three-dimensional printing is proposed for making the detector housing with heat conductors incorporated in its wall structure.

Low-temperature thermal conductance in three-dimensional nanowire embedded with phonon cavity

2014 ◽  
Vol 28 (24) ◽  
pp. 1450193
Author(s):  
Xin-Jun Wang ◽  
Xiao-Fang Peng ◽  
Meng-Dong He
Keyword(s):  
Low Temperature ◽  
Sound Velocity ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Thermal Conductance ◽  
Dominant Factor ◽  
Scalar Model ◽  
Phonon Modes ◽  
Lateral Width ◽  
Transport Region

In this paper, we investigate low-temperature thermal conductance in three-dimensional nanowire embedded with phonon cavity based on the full scalar model of elasticity. The results show that at very low temperatures, the cavity can enhance the thermal conductance in certain lateral-width range, just as the constructive coupling of more phonon-modes excited in the cavity with modes in the transport region. At higher temperatures, however, the scattering of more interfaces formed from the cavity become a dominant factor to suppress the phonon transmission. Moreover, it is found that while the material in the cavity is substituted for the material with higher sound velocity than that in the transport region, the thermal conductance is also enhanced.

Study of Low-Temperature Wafer Bonding With Au-Au Bonding Technique

2008 ◽  
Author(s):  
H. Kurotaki ◽  
H. Shinohara ◽  
H. Kobayashi ◽  
J. Mizuno ◽  
S. Shoji
Keyword(s):  
Low Temperature ◽  
Wafer Bonding ◽  
Diffusion Bonding ◽  
Low Temperatures ◽  
The Other ◽  
High Brightness ◽  
Metal Bonding ◽  
Metal Diffusion ◽  
Integrated Devices ◽  
Bonding Technique

In general, metal diffusion bonding is carried out at a temperature in the range of 300 ∼ 400 °C and is well documented [1]. However, the knowledge of metal bonding at low temperatures below 300 °C is inadequate yet. On the other hand, low temperature metal bonding is of importance in realizing advanced integrated devices such as MEMS-Semiconductors and high-brightness LED. This paper reports the results of a feasibility study of low-temperature metal bonding with the use of Au-Au diffusion bonding technique.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

Three Dimensional Structure of UMo8O26: Ordering of U-Vacancies

2002 ◽  
Vol 718 ◽  
Author(s):  
N.D. Zakharov ◽  
P. Werner
Keyword(s):  
Low Temperatures ◽  
Driving Force ◽  
Three Dimensional ◽  
Solid State Reaction Method ◽  
Dimensional Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Edx Microanalysis

AbstractThe structure and composition of UMo8O26 synthesized by solid state reaction method have been investigated by High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction, and EDX microanalysis. The ordering of U vacancies results in considerable enlargement of unit cell parameters: an=6.44 nm, bn=1.45 nm, cn=1.6 nm. It is build up of four layers piled up in c direction. Each following layer is shifted relative to previous one by vector bn/4. Eight hexagonal tunnels in each layer are filled by U atoms, while the eight others are vacant (V). Interaction between U cations and vacancies is driving force for ordering. The variation of stoichiometry can be a reason for appearance of incommensurate modulations in these crystals. It seems plausible that this structure might also exhibit superconductivity at low temperatures.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

scholarly journals Rapid Growth of TiO2 Nanoflowers via Low-Temperature Solution Process: Photovoltaic and Sensing Applications

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 566 ◽  
Author(s):  
M. Akhtar ◽  
Ahmad Umar ◽  
Swati Sood ◽  
InSung Jung ◽  
H. Hegazy ◽  
...  
Keyword(s):  
Low Temperature ◽  
Anatase Phase ◽  
Three Dimensional ◽  
Solution Process ◽  
Dye Sensitized Solar Cell ◽  
Sensor Applications ◽  
Dye Sensitized ◽  
Sensing Applications ◽  
Density Growth ◽  
Temperature Solution

This paper reports the rapid synthesis, characterization, and photovoltaic and sensing applications of TiO2 nanoflowers prepared by a facile low-temperature solution process. The morphological characterizations clearly reveal the high-density growth of a three-dimensional flower-shaped structure composed of small petal-like rods. The detailed properties confirmed that the synthesized nanoflowers exhibited high crystallinity with anatase phase and possessed an energy bandgap of 3.2 eV. The synthesized TiO2 nanoflowers were utilized as photo-anode and electron-mediating materials to fabricate dye-sensitized solar cell (DSSC) and liquid nitroaniline sensor applications. The fabricated DSSC demonstrated a moderate conversion efficiency of ~3.64% with a maximum incident photon to current efficiency (IPCE) of ~41% at 540 nm. The fabricated liquid nitroaniline sensor demonstrated a good sensitivity of ~268.9 μA mM−1 cm−2 with a low detection limit of 1.05 mM in a short response time of 10 s.

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