A temperature controlled low field nuclear magnetic resonance (LF-NMR) T2 relaxometry technique based on the mobility changes of water trapped in hydrogels, was successfully used for on-line determination of the sol-gel transition temperature for chitosan/β-glycerophosphate (CS/GP) hydrogels in real time. The LF-NMR results indicated that the gelation temperature decreased gradually with increasing GP concentration, and the results were supported by both thermogravimetric differential scanning calorimetry (DSC) and rheological findings; however, LF-NMR allows non-destructive monitoring of samples during continuous heating. Moreover, as the mobility of water molecules varies greatly during the sol-gel phase transition, the LF-NMR measurement was more sensitive and accurate (RSD ≤ 0.1 %, n = 5) compared with DSC (RSD: 1.2 %-3.7 %, n = 5) and rheology (RSD: 1.1 %-2.3 %, n = 5).

中文翻译：

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通过低场NMR在线监测热敏壳聚糖/β-甘油磷酸水凝胶的溶胶-凝胶转变温度。

基于捕获在水凝胶中水的迁移率变化的温控低场核磁共振（LF-NMR）T2弛豫技术已成功用于在线测定壳聚糖/β-甘油磷酸（CS）的溶胶-凝胶转变温度/ GP）实时水凝胶。LF-NMR结果表明，随着GP浓度的增加，胶凝温度逐渐降低，热重差示扫描量热法（DSC）和流变学结果均支持该结果。但是，LF-NMR可以在连续加热过程中对样品进行无损监测。此外，由于水分子的迁移率在溶胶-凝胶相变过程中变化很大，因此与DSC（RSD：1.2％-3.7％，RSD≤0.1％，n = 5）相比，LF-NMR测量更加灵敏，准确。