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Soft and Hybrid Materials Facility (SMF)

Overview

SMF is dedicated to fundamental research on interfaces found in systems containing polymers and low molecular weight amphiphiles. SMF provides a research facility for analysis and characterization of synthetic polymers, soft materials and polymer devices.

SMF aims to provide

  • Safe and clean working environment
  • Reasonable usage cost
  • Well calibrated equipment
  • Helpful advices and resources

Available equipment

  • Differential Scanning Calorimetry (DSC)
  • Dynamic Light Scattering (DLS)
  • Langmuir-Blodgett (LB) Trough Instrument
  • Imaging Ellipsometer
  • Profilometer
  • Mechanical Testing Equipment (Instron)
  • Oxygen Plasma Cleaner
  • Impedance Analyzer
  • Atomic Force Microscopy (AFM)
  • Ellipsometer

Contact Information

Jeffrey Tok
(650) 725-2990

Cognizant Faculty Advisor

Curtis W. Frank

 

Research Examples


Sizing of the QD nanoparticles was achieved by using the SMF Brookhaven 90 plus Dynamic Light Scattering (DLS) nanosizer. Source: Y. Xing, et al., Biochem. & Biophys. Res. Com. 372 (2008)

 

Thermal transitions of various extruded polymeric films were measured using the SMF differential scanning calorimeter (DSC). Source: Q. Liao, et al., Polymeric S&E (2012) DIO:10.1002/pen.23087

 

Monolayer Self-Assembly : The SMF Langmuir–Blodgett trough was used to fabricate monolayers of nanospheres on 4 inch quartz wafers. Source: Hsu, et al. Adv. Energy Mater.  (2012)

 

 

Getting Started

In order to become a qualified user on the tool, you need to follow each of these steps in the order as listed here:

 

 

Equipment Descriptions

Differential Scanning Calorimetry - Differential scanning calorimetry (DSC) is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. Generally, the temperature program for a DSC analysis is designed such that the sample holder temperature increases linearly as a function of time. The reference sample should have a well-defined heat capacity over the range of temperatures to be scanned. Differential scanning calorimetry can be used to measure a number of characteristic properties of a sample. Using this technique, it is possible to observe fusion and crystallization events as well as glass transition temperatures (Tg). DSC can also be used to study oxidation, as well as other chemical reactions.

Dynamic Light Scattering - Dynamic light scattering (also known as Photon Correlation Spectroscopy or Quasi-Elastic Light Scattering) is a technique in physics, which can be used to determine the size distribution profile of small particles in suspension or polymers in solution. It can also be used to probe the behavior of complex fluids such as concentrated polymer solutions. When light hits small particles, the light scatters in all directions (Rayleigh scattering) so long as the particles are small compared to the wavelength (below 250 nm). If the light source is a laser, and thus is monochromatic and coherent, then one observes a time-dependent fluctuation in the scattering intensity. These fluctuations are due to the fact that the small molecules in solutions are undergoing Brownian motion and so the distance between the scatterers in the solution is constantly changing with time. This scattered light then undergoes either constructive or destructive interference by the surrounding particles and within this intensity fluctuation, information is contained about the time scale of movement of the scatterers.

Langmuir-Blodgett Trough - Langmuir-Blodgett (LB) trough is an apparatus that is used to compress monolayers of molecules on the surface of a given subphase (usually water) and measures surface phenomena due to this compression. It can also be used to deposit single or multiple monolayers on a solid substrate. The LB trough's general objective is to study the properties of monolayers of amphiphilic molecules. An amphiphilic molecule is one that contains both a hydrophobic and hydrophilic domain (e.g. soaps and detergents). The LB trough allows investigators to prepare a monolayer of amphiphilic molecules on the surface of a liquid, and then compress or expand these molecules on the surface, thereby modifying the molecular density, or area per molecule. This is accomplished by placing a subphase (usually water) in a trough, spreading a given amphiphile over the surface, and then compressing the surface with barriers (see illustration). The monolayer's effect on the surface pressure of the liquid is measured through use of a Wilhelmy plate, electronic wire probes, or other types of detectors. An LB film can then be transferred to a solid substrate by dipping the substrate through the monolayer.

Ellipsometry - Ellipsometry is a versatile and powerful optical technique for the investigation of the dielectric properties (complex refractive index or dielectric function) of thin films. It has applications in many different fields, from semiconductor physics to microelectronics and biology, from basic research to industrial applications. Ellipsometry is a very sensitive measurement technique and provides unequalled capabilities for thin film metrology. As an optical technique, spectroscopic ellipsometry is non-destructive and contactless. Upon the analysis of the change of polarization of light, which is reflected off a sample, ellipsometry can yield information about layers that are thinner than the wavelength of the probing light itself, even down to a single atomic layer. Ellipsometry can probe the complex refractive index or dielectric function tensor, which gives access to fundamental physical parameters and is related to a variety of sample properties, including morphology, crystal quality, chemical composition, or electrical conductivity. It is commonly used to characterize film thickness for single layers or complex multilayer stacks ranging from a few angstroms or tenths of a nanometer to several micrometers with an excellent accuracy.

Imaging Ellipsometry (EP3) - Ellipsometry can also be done as imaging ellipsometry by using a CCD camera as a detector. This provides a real time contrast image of the sample, which provides information about film thickness and refractive index. Advanced imaging ellipsometer technology operates on the principle of classical null ellipsometry and real-time ellipsometric contrast imaging, using a single-wavelength ellipsometer setup with a laser as light source.

Profilometer - Profilometer is a measuring instrument used to measure a surface's profile, in order to quantify its roughness. Vertical resolution is usually in the nanometer (nm) level, though lateral resolution is usually poorer. A diamond stylus is moved vertically in contact with a sample and then moved laterally across the sample for a specified distance and specified contact force. A profilometer can measure small surface variations in vertical stylus displacement as a function of position. A typical profilometer can measure small vertical features ranging in height from 10 nm to 1 mm. The height position of the diamond stylus generates an analog signal which is converted into a digital signal stored, analyzed and displayed. The radius of diamond stylus ranges from 20 nm to 25 μm, and the horizontal resolution is controlled by the scan speed and data signal sampling rate. The stylus tracking force can range from less than 1 to 50 mgs.

Instron Mechanical Tension/Compression Tester - Tension testers, or pull testers, are used to determine the tensile strength of various materials from metals to plastics. The Instron tensile testing system utilizes the tension test to perform mechanical test on material. Tensile tests are simple, relatively inexpensive, and fully standardized. By pulling on something, one can very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, one will find its strength along with how much it will elongate. Standard tensile forces can be applied with an electromechanical tensile tester while higher tension loads require a static hydraulic tensile system.

Oxygen Plasma Prep Cleaner - Plasma cleaning involves the removal of impurities and contaminants from surfaces through the use of an energetic plasma created from gaseous species. Gases such as argon and oxygen, as well as mixtures such as air and hydrogen/nitrogen are used. In a plasma, gas atoms are excited to higher energy states and ionized. As the atoms and molecules 'relax' to their normal, lower energy states they release a photon of light, this results in the characteristic "glow" or light associated with plasma. Different gases give different colors. For example, oxygen plasma emits a light blue color. A plasma's activated species include atoms, molecules, ions, electrons, free radicals, metastables, and photons in the short wave ultraviolet (vacuum UV, or VUV for short) range. This 'soup', which incidentally is around room temperature, then interacts with any surface placed in the plasma. If the gas used is oxygen, the plasma is an effective, economical, environmentally safe method for critical cleaning. The VUV energy is very effective in the breaking of most organic bonds (i.e., C-H, C-C, C=C, C-O, and C-N) of surface contaminants. This helps to break apart high molecular weight contaminants. A second cleaning action is carried out by the oxygen species created in the plasma (O2+, O2-, O3, O, O+, O-, ionised ozone, metastably-excited oxygen, and free electrons). These species react with organic contaminants to form H2O, CO, CO2, and lower molecular weight hydrocarbons. These compounds have relatively high vapour pressures and are evacuated from the chamber during processing. The resulting surface is ultra-clean.

Impedance Analyzer - Almost every liquid and solid is able to pass current when a voltage is applied to it. If a variable (ac) voltage is applied to the material, the ratio of voltage to current is known as the impedance. The measured impedance varies with the frequency of the applied voltage in a way that is related to the properties of the liquid or solid. Electric impedance is a well established technique for studying the electrical properties of polymer materials because their dielectric properties and relaxation events within polymers are nicely matched by accessible frequencies from the impedance analyzer.

Atomic Force Microscope