The application of MALDI-TOF-MS and NMR in the investigation of chain structural differences of hydroxypropyl...

Hydroxypropyl cellulose (HPC) is a widely used bio-based material typically prepared by the hydroxypropylation of cellulose. The properties of HPC vary considerably with the cellulose source and synthesis conditions. While previous research has predominantly focused on HPC preparation, phase transition behavior, and applications, only a few studies have been conducted on its chain structures and heterogeneity among different HPC samples. To bridge this knowledge gap, we synthesized HPC samples with a molar substitution (MS) of 3.0 under atmospheric pressure using both homogeneous and heterogeneous systems. Subsequently, the structural characteristics of these laboratory-synthesized HPCs, along with commercial products, were thoroughly characterized by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS), coupled with Nuclear Magnetic Resonance (NMR) spectroscopy, this approach enabled a comparative analysis of the hydroxypropyl (HP) substitution patterns. The results revealed significant differences in the substitution patterns between HPCs from homogeneous and heterogeneous conditions. Furthermore, these distinct patterns were conclusively linked to the observed differences in the macroscopic properties of the HPCs, providing crucial insights into the structure-property relationships.