(71b) Effect of Methyl Substitution Extent and Pattern on Multiscale Assembled Structure in Methylcellulose Gels

Methylcellulose (MC) is a cellulose derivative with some hydroxyl groups replaced with methoxy groups. MC undergoes thermoreversible gelation at elevated temperatures, and it is widely used as a rheology modifier in foods, construction materials, and biomedical applications. Commercial MC is typically synthesized using techniques that yield a heterogeneous substitution of methoxy groups along the polymer backbone, with a degree of substitution (DS) of around 1.8 methoxy groups per monomer. Over the past decade, it has been shown that the gelation of commercial MC at around 50-60°C occurs as individual MC chains aggregate into semi-flexible fibrils that make up a gel. However, alternative synthesis methods can yield MC with a more homogenous substitution pattern and controlled block copolymers of MC monomers with different substitutions. Such changes to the distribution of hydrophobic groups along the MC backbone have been shown to have profound impact on the gelation temperature and behavior of MC, but the extent to which the structure of MC fibrils changes because of different substitution patterns remains unknown. As synthesis techniques develop further, a strong understanding of this relationship would allow design of MC with ideal properties for a given application, but such an understanding has been limited by the large design space of methyl substitution pattern. In this talk, we will share our ongoing work using a combination of data-driven exploration and physics-based coarse-grained molecular dynamics simulations to investigate how the DS and substitution pattern impact the self-assembly of MC chains in aqueous solution.