<![CDATA[This structured critical review evaluated how nominal polyethylene glycol (PEG) grade affects lignocellulose fractionation in deep eutectic solvents using an auditable corpus of 42 retained studies, including three within-study PEG-grade series. The eucalyptus studies showed modest PEG400 advantages for selected responses, whereas a sugarcane-bagasse screen gave the highest lignin removal (83.23%), glucose concentration, and glucose yield at PEG600, with lower cellulose retention than at PEG200/400; multivariable optimization subsequently selected PEG400. These contrasts show that nominal grade is a formulation variable rather than an isolated molecular-weight effect: equal PEG mass changes chain and terminal-hydroxyl concentrations, whereas a fixed choline chloride:PEG molar ratio also changes polymer mass and repeat-unit content. Candidate explanations are organized into four pathways—interaction-network modification; viscosity, diffusion, and steric trade-offs; phase behavior and partitioning; and lignin stabilization/carbohydrate protection. Current evidence supports formulation-dependent grade responses but not a universal grade ranking or numerical optimum. MW-REPORT is proposed to standardize grade characterization, normalization, mediator measurements, and product balances needed for reproducible formulation-specific selection.]]>
Copyrights © 2026
