Temperature-Induced Hydrogen Bond Dynamics in Cellulose Iβ

Hydrogen bonds govern the structure, dynamics, and mechanical properties of biopolymers, yet experimental insights into their temperature-dependent behavior remain limited. Here, we used inelastic neutron scattering (INS) to probe hydrogen-bond dynamics in cellulose nanocrystals derived from softwood that possess the cellulose Iβ crystal structure. Preferential particle alignment enabled investigation of motions along and transverse to the polymer chains. Temperature-dependent phonon density of states (GDOS) revealed transient redistribution of vibrational spectral weight between 300 and 340 K, consistent with hydroxymethyl conformational rearrangements and hydrogen bond reorganization. Directional measurements further revealed that motions along the cellulose chains are more sensitive to conformational rearrangements than transverse motions. The INS and GDOS measurements are consistent with temperature-induced hydrogen bond rearrangements in cellulose, offering a mechanistic framework relevant to hydrogen bonded, anisotropic polymers. Insights from this work may guide the design of nanocellulose-based and other polymeric materials with tailored heat transport and mechanical properties.