(263h) Polymer Property Modelling for the Design of the Structured Products

Designing new and better chemical products based on specific desired properties, to satisfy consumer demands, is a main activity in chemical, material and pharmaceutical industries. Molecular level investigation to produce these new chemical products using the traditional trial-and-error methodology is highly time consuming, tedious, capital intensive and difficult to automate. Emerging technologies involve the use of computer aided molecular design (CAMD) techniques that can partially replace the same. Using CAMD, one can determine molecules that match a specific set of target properties. In order to extend CAMD techniques to macromolecules like polymers, new property models that can be used with CAMD techniques are required. The main objective of this paper is to present the development of new property models for predicting polymer properties based on analysis of the polymer structure.

Group contribution methods form the basis of this work. Marrero-Gani[1] groups are used in this work, due to the wider range of availability of groups which allows handling of a large range of polymer structures. Combinations of cheminformatics, computational chemistry and GRID technology is used for developing this new model for predicting polymer properties based on their structure. A parallel atom-connectivity based property model is also developed, so that the contributions of missing groups can be predicted. Cheminformatics is used to identify the polymer structure property relationships. The grid technology is employed to reduce the time for developing the property models, that is, several property models are developed simultaneously.

The property model parameters (group contributions) for the set of Marrero-Gani[1] groups and the atom-connectivity parameters (representing the groups) have been determined. This allows for any specific polymer structure, during the property prediction, to estimate any missing group/ group contribution by using the atom connectivity indices. Combined group-atom connectivity model can be regarded as a group-contribution plus (GC+) property model for polymers. Several properties of polymers like amorphous volume, crystalline volume, glass transition temperature, solubility parameter, refractive index, permeability, thermal conductivity, dielectric constant and heat capacity of solid and liquid polymers have been developed. To evaluate the performance of the developed models, predicted properties using this model have been compared with those reported by Van Krevelen[2] and Bicerano[3]. The validated property models have been used in CAMD techniques to generate candidate polymer structures matching specified design targets. This paper will highlight the developed GC-plus polymer property models together with illustrations on how they can be used in polymer based product design.

Reference: [1] J. Marrero and R. Gani, Fluid Phase Equilibria 183-184(2001) 183-208. [2] D.W. Van Krevelen, Properties of Polymers, Elsevier (third completely revised edition 1990). [3] Bicerano, J., Prediction of Polymer Properties, Marcel Dekker, Inc., 2002.