Bioresource Processing Research Institute of Australia (BioPRIA), Monash University, Clayton, Victoria 3800, Australia.
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
J Colloid Interface Sci. 2020 May 15;568:234-244. doi: 10.1016/j.jcis.2020.02.048. Epub 2020 Feb 14.
The water absorption capacity of nanocellulose (NC) foam is tailored by crosslinking with polyethyleneimine (PEI) and hexamethylenediamine (HMDA). The interaction of amine groups in PEI and HMDA with the carboxylic groups (COO) of NC affects the foam structure which reduces its swelling capacity.
Functionalised NC foams were prepared by TEMPO (2,2,6,6,-tetramethylpiperidine-1-oxyl) oxidation of bleached pulp, followed by fibrillation into a hydrogel, adding a crosslinker and freeze drying the hydrogel into a foam. The structure of the NC foam characterised by rheology, SANS (Small Angle Neutron Scattering), SAXS (Small Angle X-ray Scattering) and cryo-SEM (cryo-Scanning Electron Microscopy) was related to absorption and swelling properties.
The NC foam has the highest water absorption capacity at 132 g water/g foam. PEI-NC foam has a water absorption capacity of 71 g water/g foam, which further decreases to 47 g water/g foam for the HMDA-NC foam. Small angle scattering reveals the elementary fibril of NC is 3-5 nm thick and forms fiber bundles. In water, these bundles swell differently for the different types of foam which affects the water absorption capacity of the network. The structural analysis of the foam was related to the swelling capacity. The structure of NC foam can be engineered for specific applications for biomedical, agriculture or food industries.
通过与聚乙烯亚胺（PEI）和己二胺（HMDA）交联，可以调整纳米纤维素（NC）泡沫的吸水性。PEI 和 HMDA 中的胺基与 NC 的羧酸基团（COO）相互作用会影响泡沫结构，从而降低其溶胀能力。
通过 TEMPO（2,2,6,6,-四甲基哌啶-1-氧自由基）氧化漂白浆，制备功能化 NC 泡沫，然后将其纤化为水凝胶，加入交联剂并将水凝胶冷冻干燥成泡沫。通过流变学、小角中子散射（SANS）、小角 X 射线散射（SAXS）和冷冻扫描电子显微镜（cryo-SEM）对 NC 泡沫的结构进行了表征，研究了其与吸收和溶胀性能的关系。
NC 泡沫的吸水率最高，为 132 g 水/g 泡沫。PEI-NC 泡沫的吸水率为 71 g 水/g 泡沫，而 HMDA-NC 泡沫的吸水率进一步降至 47 g 水/g 泡沫。小角散射表明，NC 的基本原纤厚度为 3-5nm，并形成纤维束。在水中，这些束的溶胀方式因泡沫的类型而异，这会影响网络的吸水能力。对泡沫的结构分析与溶胀能力有关。可以针对生物医学、农业或食品工业的特定应用对 NC 泡沫的结构进行设计。
