A wealth of information on molecular dynamics lies buried in the shapes of infrared bands and Raman lines. Data obtained in the frequency domain has a counterpart in the time domain in the form of a time-correlation function, which is sensitive to molecular dynamics and relaxation processes in the picosecond time range. Band shape studies can provide information on rotational relaxation (usually in small molecules), the duration of “sticky” collisions (e.g., those involving hydrogen bonds), the dynamics of strong interactions, the coupling of local vibrations with lattice motions, and so on. In recent work, we have focused on the 1583 cm -1 ring mode in the infrared spectra of atactic polystyrene. The 1583 cm -1 band is influenced by an anharmonic coupling to lower frequency lattice modes that provide a mechanism of relaxation. Vibrational relaxation in this mode can be modeled in terms of two relaxation processes. The first is of the order of 0.01 picoseconds and corresponds to a fast vibration in a local cage of neighbors and is largely insensitive to temperature changes. The second is in the 1–10 picosecond time range and shows very different behavior, as illustrated in the plot opposite. The relaxation time increases as the T g is approached from low temperatures, followed by an abrupt decrease starting at temperatures near 160˚C, close to 1.2T g K. This relaxation corresponds to the fast process, observed in neutron scattering experiments. The decrease at 1.2T g is a critical temperature (T c ) identified in mode coupling theory and these observations provide important experimental support for this theory Plot of the correlation time for the 1583 cm -1 bands of atactic polystyrene corresponding to inhomogeneous broadening, calculated, as a function of temperature.. The 1583 cm -1 mode is in Fermi resonance with a combination mode and is therefore more sensitive to vibrational relaxation through a transfer of energy to lattice modes. Relaxation processes change about 20˚C below the thermally observed T g and again at a temperature close to 1.2T g. Vibrational Relaxation in Polymers Paul C. Painter, Pennsylvania State Univ University Park, DMR

Polymer Education – The Development of Textbooks and On-Line Courses Paul C. Painter, Pennsylvania State Univ University Park, DMR Thanks to previous NSF support, over the years we have been able to amass a wealth of visual material constructed by people with far more artistic and technical drawing ability than ours. Some of this material was previously used to author CDs, but we have recently used these illustrations in a new textbook, Essentials of Polymer Science and Engineering. In this book, we have attempted to do things differently to conventional texts. First, it is in color, taking advantage of the striking visual material produced by our collaborators. The usual topics are discussed, but here and there we have include what we call Polymer Milestones, brief summaries of the contributions of some great scientists and interesting characters to the field. In addition, books such as this, which are largely concerned with general principles, often do not give students a feel for the nature and use of specific polymers, so we have also sprinkled in some brief reviews of Fascinating Polymers. These are aimed at giving a student a feel for the depth of this field and its rich history. Many of these figures and animations are also being used to produce on-line lectures, an on-going, time-consuming project, which will be open source and freely available on the web.