TEMPO-mediated oxidation of native cellulose. The effect of oxidation conditions on chemical and crystal structures of the water-insoluble fractions
TEMPO-mediated oxidation of native cellulose. The effect of oxidation conditions on chemical and crystal structures of the water-insoluble fractions
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DOI：
10.1021/bm0497769
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发表时间：
2004-09-01
影响因子：
6.2
通讯作者：
Isogai, A
中科院分区：
文献类型：
--
作者：
Saito, T;Isogai, A
以次氯酸钠为氧化剂，溴化钠和2，2，6，6-四甲基哌啶氧自由基（克里思）为催化剂，在不同条件下对纤维素棉短绒进行氧化。在此TEMPO介导的氧化后，收集水不溶性级分，并根据羧酸盐和醛含量、堆积和晶体尺寸、聚合度、形态和保水性值进行表征。通过氧化，将羧酸根和醛基分别引入到水不溶性级分中高达约0.7和0.3 mmol/g，其中水不溶性级分的回收率通常高于80%。纤维素I的结晶度和晶体尺寸在氧化过程中几乎没有变化，因此，羧酸根和醛基选择性地引入晶体表面和水不溶性组分的无序区域。通过引入亲水性羧酸基团和通过TEMPO介导的氧化从纤维形式到短片段的形态变化，棉短绒的保水值可以从60%增加到约280%。
Cellulose cotton linter was oxidized with sodium hypochlorite with catalytic amounts of sodium bromide and 2,2,6,6-tetramethylpiperidine-l-oxyl radical (TEMPO) under various conditions. After this TEMPO-mediated oxidation, water-insoluble fractions were collected and characterized in terms of carboxylate and aldehyde contents, crystallinities and crystal sizes, degrees of polymerization, morphology, and water retention values. Carboxylate and aldehyde groups were introduced into the water-insoluble fractions up to about 0.7 and 0.3 mmol/g, respectively, by the oxidation, where recovery of the water-insoluble fractions were generally higher than 80%. Crystallinities and crystal sizes of cellulose I were nearly unchanged during the oxidation, and thus, carboxylate and aldehyde groups were introduced selectively on crystal surfaces and in disordered regions of the water-insoluble fractions. Water retention values of cotton linter can be increased from 60% to about 280% through the introduction of hydrophilic carboxylate groups and morphological changes from fibrous forms to short fragments by the TEMPO-mediated oxidation.