POLYMER INFORMATICS SOFTWARE FOR DE NOVO POLYMER DESIGN

Throughout the twentieth century, the availability of petrochemically derived synthetic polymers has had a profound effect on society. Polymer systems have provided efficient and innovative materials for a broad range of applications and have been of paramount importance in increasing living standards and improving the quality of life. As is often the case with advancement, the need for materials innovation in polymer science has increased with time. In addition to the traditional needs of improved quality, increased efficiency, and reduced costs, concerns related to sustainability have led a revival and growth of interest in biobased polymers, with a strong focus on biobased precursors and the polymers that can be synthesized at least partially from biobased precursors.

Although polymers have been carefully studied for many decades, only a small fraction of the full design space of all synthesizable polymers has been explored. Vast regions of chemical space have yet to be synthesized and evaluated.

Polymer informatics is defined as cheminformatics focusing on polymers. Dr. Bicerano recently developed Polymer Expert, a polymer informatics software tool for de novo polymer design (please watch this introductory webinar), in collaboration with Materials Design, Inc. Polymer Expert was incorporated into Version 3.8 of the MedeA software suite. It includes a comprehensive and carefully curated database, and query and search engines, to provide an innovative and validated methodology for the exploration of polymer property and chemical space.

The methodology used in MedeA Polymer Expert and two examples of applications are summarized below. Further information is provided in the documentation set and tutorials of MedeA, a research monograph (J. Bicerano, Prediction of Polymer Properties, revised and expanded third edition, Marcel Dekker, New York, 2002), and a peer-reviewed paper (J. Bicerano, D. Rigby, C. Freeman, B. LeBlanc, and J. Aubry, "Polymer Expert – A Software Tool for de novo Polymer Design", Computational Materials Science, Volume 235 (2024) 112810, open access link. Download PDF).

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Methodology

MedeA Polymer Expert employs a unique database, the Polymer Expert Analog Repeat-unit Library, or PEARL, which has been constructed to be comprehensive in chemical and property space, and representative of systems which are not overly complex synthetically. PEARL contains more than 1.1 million repeat units and has a foundation comprised of a curated library of standard repeat units which have been reported and characterized in scientific literature. MedeA Polymer Expert includes a query interface, a search engine, and reporting methodologies. It can be employed graphically, and on background basis using the MedeA JobServer and Flowchart capabilities.

Example 1: Biobased PET Alternatives

Employing a query based on six properties as shown in the following table, MedeA Polymer Expert is used in a similarity search to identify repeat units that can be synthesized at least partially from biobased precursors.

The results of this query include furanoate-based olefin repeat units, which indeed provide a good correspondence with the typical PET properties listed above. Poly(ethylene furanoate), which is a bioderived polymer, is of course a well-known potential replacement for PET.

Example 2: Highly Crystalline Polypropylene Homopolymer Alternatives

Highly crystalline polypropylene homopolymer (PPHP) exhibits high strength to weight ratio characteristics, excellent chemical resistance, a high degree of thermoformability, corrosion resistance, and no moisture absorption. As such, it is a very widely employed plastic. Nevertheless, the desire to improve sustainability, and the continued optimization of materials for consumer products, leads to interest in identifying potential alternatives.

The property query shown below can easily be constructed and executed using MedeA Polymer Expert, leading to the search results illustrated in the subsequent figure. Note that this query combines similarity based criteria, which employ a numerical weight, with logical criteria for the density and dielectric constant which must be obeyed for a result to be obtained for a given repeat unit.

The following table compares property targets (excluding properties for which only a pass-fail criterion is imposed) with values for candidates providing closest match, and the ranges obtained over 20 candidates providing closest matches in a search for PPHP alternatives.

This example, employing the PEARL database to search for alternatives to PPHP, provides rapid insights into the types of repeat units to consider. MedeA Polymer Expert queries can be adjusted interactively to examine, for example, the sensitivity of search results to individual property criteria, such as in this case the dielectric constants used to exclude more polarizable repeat units.

Summary

Developed by Dr. Bicerano in collaboration with Materials Design, Inc., MedeA Polymer Expert is a versatile and user-friendly tool for de novo polymer design, optimization, and analysis. This new tool can be used to rapidly generate novel candidate repeat units to meet desired polymer performance targets.

Two examples of applications were provided in this post. These examples involve the identification of biobased alternatives for poly(ethylene terephthalate) (PET), and the selection of possible alternatives for highly crystalline polypropylene homopolymer (PPHP). In both of these examples, many promising candidates were unobvious and unlikely to have been identified without using a polymer informatics approach.