Real-time in-situ measurement of hydrogel swelling by single sided NMR

Abstract

Swelling factor and swelling rate are key characteristics of hydrogels. Here, a new method is presented for accurate in-situ monitoring of hydrogel swelling in real-time using single-sided nuclear magnetic resonance (NMR) profiling. The method reduces experimenter bias and uncertainty intrinsic to common weighing and caliper methods. Moreover, NMR allows monitoring of samples that may otherwise be inaccessible to other methods, for instance in opaque or sealed containers. The method is straightforward and does not require deep knowledge of NMR principles from the experimenter. This NMR profiling method estimates similar swelling factors to those using the weigh and caliper method, with precision equivalent to the weigh method and significantly better than with caliper. Unlike weigh and caliper methods, NMR profiling additionally provides dynamic swelling rates over time, without needing to touch or modify the sample.