Recently nanocelluloses have been found to possess ice recrystallization inhibition (IRI) activity, which have several potential applications. The present study focuses on the relationship between the surface charge density (SCD) of nanocelluloses and IRI activity. Cellulose nanocrystals (CNCs) and 2, 2, 6, 6-tetramethylpiperidine-1-oxyl oxidized cellulose nanofibrils (TEMPO-CNFs) with similar degrees of polymerization (DP) or fibril lengths but with different SCDs were prepared and characterized for IRI activity. When the SCD of CNCs was progressively reduced, an initial increase of IRI activity was observed, followed by a decrease due to fibril aggregation. CNCs with a low SCD became IRI active at increased unfrozen water fractions and higher annealing temperatures. TEMPO-CNFs with a low SCD also had higher IRI activity. Additionally, lowering pH to protonate the carboxylate groups of TEMPO-CNFs enhanced the IRI activity. These research findings are important in producing nanocelluloses with enhanced IRI activity and understanding their structure-activity relationship.

中文翻译：

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表面电荷密度对纳米纤维素的冰重结晶抑制活性的影响。

近年来，发现纳米纤维素具有冰重结晶抑制（IRI）活性，其具有多种潜在应用。本研究的重点是纳米纤维素的表面电荷密度（SCD）与IRI活性之间的关系。制备了具有相似聚合度（DP）或原纤维长度但具有不同SCD的纤维素纳米晶体（CNC）和2、2、6、6-四甲基哌啶-1-氧基氧化纤维素纳米原纤维（TEMPO-CNF），并对其IRI活性进行了表征。当CNCs的SCD逐渐降低时，观察到IRI活性最初增加，然后由于原纤维聚集而降低。具有低SCD的CNC在未冻结的水含量增加和退火温度升高时变为IRI活性。SCD较低的TEMPO-CNF也具有较高的IRI活性。另外，降低pH以质子化TEMPO-CNFs的羧酸酯基团可增强IRI活性。这些研究结果对于生产具有增强的IRI活性的纳米纤维素以及了解其结构-活性关系非常重要。