2D NMR analysis of ethylcellulose

2-D NMR was used to characterize native and acid hydrolyzed ethylcellulose (EC), a Hercules product widely used as a film-former in ink and coatings applications and as a binder and filler in pharmaceutical applications. An important parameter in controlling the proper-ties of ethylcellulose is the degree of substitution (DS) of ethyl functionalities on the cellulose backbone. NMR is one technique that was used to determine both the total and positional DS (ethylation at the 2,3 and 6 positions of the anhydroglucose unit (AGU)). This analysis requires complete hydrolysis of the sample, and an improved acid hydrolysis technique was developed for this application. Two-dimensional (2-D) NMR techniques were used to confirm peak assignments related to positional DS determinations that were previously made by comparison with standards. In addition, 2-D NMR methods were used to evaluate positional DS of native ethylcellulose prior to acid hydrolysis. A comparison of the analytical results for the acid hydrolysate and native polymer will be discussed.