The Theoretical and Computational Chemistry program is supporting Professor Rigoberto Hernandez at the Georgia Institute of Technology as part of the CAREER program for young scientists. The objective of this research is to characterize the time-dependent behavior of the polymerization process. A bond percolation model on a novel lattice has been combined with an Ising-like Polymer Growth Hamiltonian (PGH) to provide non-uniform and correlated bond formation/breaking probabilities. It includes the pertinent reaction dynamics, but is simple enough to accommodate the Monte Carlo treatment of high (long-length) polymers. A new stochastic Hamiltonian has been built around the potential of mean force for the effective polymer `contour` length. The change of the macroscopic properties of the polymer as its length increases is included through an effective friction which explicitly depends on this length. Further study of the dynamics of this Hamiltonian, as well as its connection to the polymer-growth lattice Hamiltonian, should provide increased understanding of the connection between the monomer properties and reaction conditions, and of the resulting material properties of the polymer as a function of time. Hard plastics, chewing gum, glues, proteins and coatings are but a few examples of the diverse range of polymeric materials which have driven the polymer industry. Surprisingly, these materials are often obtained from the same base monomers, varying only reaction conditions and relative composition. What existing theories often leave out in their characterization of the final product is an understanding of the reaction dynamics when viscous effects affect the reaction process. This is important in thermoset polymers used in the encapsulation of microchips; the polymerization ends not because the reactants have been depleted, but because of diffusional quenching due to the dramatic change in viscosity as a function of the extent of reaction. The goal in this research is to understand the competition between the reactivity of the polymer and changes in the material's viscosity as a function of temperature and reaction profile. The educational component of this proposal comprises the development of a new physical chemistry course and a companion web-based textbook, both of which emphasize the connection between theoretical understanding and physical intuition. The course will also use various electronic forms of communication. It is hoped that this computer-enhanced dialectic (CED) will provide ample opportunity for the student to learn not only how to answer questions, but also how to ask the right ones.
