The following is based on the presentation made by Christopher N. Bowman, recipient of the MRS Outstanding Investigator Award, at the 1997 MRS Spring Meeting.

I would like to focus on our recent work involving photopolymerizations of monomers in a liquid-crystalline environment. This work is one of the many aspects of photopolymerizations that we are focusing on at the University of Colorado. In particular this effort concentrates on understanding the influence of a liquid-crystalline medium and monomer segregation on polymerization behavior and polymer structure. These studies are of considerable importance for polymer-stabilized ferroelectric liquid crystals (FLCs) because of the enormous potential impact on the area.

I will briefly introduce liquid crystals (LCs), FLCs, and photopolymerizations. I will then discuss the observed electrooptic properties and how these properties change as the LC phase during polymerization is varied. Finally I will address how polymerization kinetics are affected by the LC phase and monomer segregation. This discussion will include results from x-ray diffraction, polarized infrared spectroscopy, and differential scanning calorimetry experiments.

Since the first reports by Aisenberg and Chabot in 1971 indicating the possibility of producing hard amorphous (so-called diamondlike) carbon (DLC) films, many experimental and theoretical research results have been published outlining the properties and film growth mechanisms of these films deposited by a variety of techniques. Polycrystalline and even quasimonocrystalline diamond thin films have also been produced, thus providing a wide range of wear and corrosion properties. The difference between these materials and graphite led to a prediction of rapid market growth for hard carbon. However this has not materialized. A large number of carbonbased films have been produced with differences in hardness, elasticity, friction coefficient, optical and electronic bandgap, electrical and thermal conductivity, and thermal stability. In addition these materials can show very different practical adhesion properties, which depend also on the substrate material and composition. Cost, deposition rate and temperature, geometry, and size of the coating chamber are additional variables. As a result, many of these materials can only be used for a limited range of applications. It is now possible to better understand the suitability of various coatings and the causes of the early failures that occurred through unsuitable material choices. This improved understanding should allow improvements in the performance and reliability of hard carbon films and perhaps trigger the kind of market growth that was originally foreseen but failed to materialize.

Low-emissivity (low-E) and solarcontrol coatings increase the energy efficiency of clear float soda-lime-silicate glass for architectural and automotive window applications. At the same time, coated glass largely maintains its neutral color and high visible transmittance. Two major classes of coated products are currently available for the architectural market: The more durable chemicalvapor- deposition (CVD) coatings are deposited on float glass as it is formed. The vacuum deposited low-E coatings, which are the subject of this article, have superior spectral performance and are deposited off-line by the sputter-deposition process. Many elements of this subjecthave been discussed in the literature, covering energy efficiency for windows, specific examples of low-E coating, a J2 6 brief outline of the deposition techniques, and a more detailed account of optical design considerations for low-E thin-film coatings, particularly for single metal-layer systems. This article briefly discusses aspects of these coatings that relate to their design, performance, and preparation. More attention is given to the materials that constitute the different layers of these coatings and to their specific properties and function.

In October 1986, the neutron scattering facility at Los Alamos National Laboratory became a national user facility and a formal user program was initiated in 1988. In July 1989, this facility was dedicated as the Manuel Lujan Jr. Neutron Scattering Center (Lujan Center) in honor of the long-term Congress representative from New Mexico. The Lujan Center, part of the Los Alamos Neutron Science Center (LANSCE), is a pulsed spallation neutron source equipped with time-of-flight neutron-scattering spectrometers for condensed-matter research. Neutron scattering is a powerful technique for probing the microscopic structure of condensed matter. The energies and wavelengths of thermal neutrons closely match typical excitation energies and interatomic distances in solids and liquids. Because neutrons have no charge, they penetrate bulk samples of material to give precise information on the positions and motions of individual atoms. The magnetic moment of a neutron interacts with unpaired electrons, making neutrons ideal for probing microscopic magnetic properties. Because neutron-scattering cross sections do not vary monotonically with the atomic number of the scattering nucleus, neutrons and x-rays can provide complementary structural information. This technique is particularly effective for structural problems in polymer and biological studies because hydrogen and deuterium scatter neutrons strongly but with different cross sections.

Polyethylene has been manufactured commercially for over sixty years. However recently a high-modulus variant has become available. This article describes the background to the development of high-modulus polyethylene and describes the story behind the sequence of scientific discoveries and technological developments that occurred to enable this advance.

Polyethylene was discovered by accident in the 1930s when two scientists working for the ICI chemical company carried out a series of experiments to study the effect of pressure on the reaction kinetics of certain organic liquids and gases. During these experiments, the scientists noted a waxy deposit in their small reaction vessel which marked the birth of one of the world's largest commodity polymers. The crystallographic structure of polyethylene was determined by another ICI industrial scientist who at the time was pioneering x-ray techniques. The crystallography of polyethylene, shown in Figure 1, is relatively simple in that it shows the long CH2-CH2 polymer chains packed in the all “trans” configuration to form an orthorhombic cell.

Polyethylene rapidly developed as a commodity thermoplastic finding application in injection molding, extrusion, and packaging. Its prime material characteristics are its toughness, flexibility, and ease of processing. The stiffness of the polymer for most applications was found to be of the order of 1 GPa, which was similar to other thermoplastics but less than metals such as aluminum at 60 GPa and steel at 210 GPa.