Active-learning and materials design: the example of high glass transition temperature polymers

Machine-learning (ML) approaches have proven to be of great utility in modern materials innovation pipelines. Generally, ML models are trained on predetermined past data and then used to make predictions for new test cases. Active-learning, however, is a paradigm in which ML models can direct the learning process itself through providing dynamic suggestions/queries for the next-best experiment. In this work, the authors demonstrate how an active-learning framework can aid in the discovery of polymers possessing high glass transition temperatures (T-g). Starting from an initial small dataset of polymer T-g measurements, the authors use Gaussian process regression in conjunction with an active-learning framework to iteratively add T-g measurements of candidate polymers to the training dataset. The active-learning framework employs one of three decision making strategies (exploitation, exploration, or balanced exploitation/exploration) for selection of the next-best experiment. The active-learning workflow terminates once 10 polymers possessing a T-g greater than a certain threshold temperature are selected. The authors statistically benchmark the performance of the aforementioned three strategies (against a random selection approach) with respect to the discovery of high-T-g polymers for this particular demonstrative materials design challenge.