Crystallization is an exothermic process (see Fig. ). In the case of small molecule crystals such as gas hydrates, the heated generated during crystal formation can lead to localized temperature increases, resulting in nascent crystal phases (i.e., crystal nuclei) with enhanced crystallinity. In turn, the mechanistic, molecular-level characteristics of small-molecule nucleation processes can depend on methodological considerations related to heat transfer conditions, such as the usage of simulations corresponding to isolated or closed systems. Experimental 5 and theoretical results indicate that lamellar thickness in polymer crystals is inversely proportional to the degree of supercooling during crystallization. Therefore, it is reasonable to conjecture that the exothermic nature of crystallization and heat transfer effects might impact polymer nucleation. While there has been some work probing the molecular-level details of polymer crystallization using simulations, it relied on isothermal simulations, and neglected the role of heat transfer during polymer crystallization. It remains an open challenge to characterize the impact of heat release on polymer nucleation.