In-silico Design of Cellulosic Hydrogels: a multiscale materials modeling framework

Global warming has led to frequent water(ice) freeze-thaw cycles, especially in the arctic regions, leading to catastrophic infrastructure damage, and loss of lives due to the unreliable concrete structures with freeze-thaw induced cracks within them. In places like Alaska, this had led to permafrost degradation causing massive structural failures and threatening the livelihood of indigenous populations. One approach to circumvent this problem is to prevent ice formation using anti-freeze materials to disable the freeze-thaw cycles. Biopolymers such as cellulosic hydrogels have been shown to prevent water from freezing, offering new directions in this effort. Motivated by these findings, we develop a multiscale modeling framework to a) understand the molecular origins of the ice-inhibition properties of cellulose, and b) aid the design of these hydrogels for engineering materials such as concrete. Using ab initio calculations, we demonstrate that cellulose units prefer binding to ice planes in tetrahedral configurations, that form the lowest energy cellulose-ice heterostructures. The resulting binding energy data is then used to develop a coarse-grained model of cellulose for classical molecular dynamics (MD). Our MD simulations elucidate the anti-freeze behavior of these hydrogels suggesting the gels confine the water molecules and disrupt their ability to reconfigure to form ice. We show that this framework is generalizable to aid the design of new biopolymers for anti-freeze properties.