(156a) Enhanced Coil Dimensions of Polyolefins: Effect of Tacticity and Side Chain Structure

The development of new polymeric materials with desirable properties hinges on a solid understanding of structure-property relationships. In this work, we evaluate the relationship between the polymer structure and their coil dimensions and explore new polyolefins based on these relations. Coil dimensions are important features of polymers which affects their performance in various applications, including drug delivery, waste-water treatment, construction material, and engine oils. Coil dimensions are dependent on the composition, topology or connectivity, molecular weights, distributions and modalities. Other contributions include the number, size, and stereo orientation of side chains along the polymer backbone. Thus, controlling these attributes allows us to tailor the coil dimensions of polymers. Understanding the fundamental physics of these systems is vital for their development.

We present a computational approach to evaluate the coil dimensions of polymers in dilute solutions. In the proposed scheme, we calculate the radius of gyration (Rg) of polymer chains using molecular dynamics simulations. We use simulated annealing to ensure the capture of different coil configurations. We demonstrate the validity of the proposed model by comparing its predictions with experimentally known Rg values of stereoregular α-olefin polymers as representative systems. We demonstrate that this approach affords the ability to quantify the effect tacticity has on the coil dimensions of polyolefins. We observe that when the polymer chains transition to a bottlebrush structure the effect of tacticity is suppressed. Furthermore, we demonstrate that the side chain steric hindrance plays an important role in the rigidity of the polymer backbone. In addition to tacticity, we use the model to evaluate the effects of polymer composition on the coil dimensions. Combining our model with virtual high-throughput screening techniques, we evaluate the coiling behavior of hundreds of new polymers. Using the screening results, we obtain correlations between the structure of the side chain and the coil dimensions of polymers.