Wet-expandable capsules made from partially modified cellulose,Green Chemistry

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Wet-expandable capsules made from partially modified cellulose
Green Chemistry ( IF 9.3 ) Pub Date : 2020-06-22 , DOI: 10.1039/d0gc01523g
Katarzyna Mystek _{1,

2,

3,

4} , Hailong Li _{1,

2,

3,

4} , Torbjörn Pettersson _{1,

2,

3,

4} , Hugo Françon _{1,

2,

3,

4} , Anna J. Svagan _{1,

2,

3,

4} , Per A. Larsson _{1,

2,

3,

4} , Lars Wågberg _{1,

1,

2,

3,

4}

Affiliation

Preparation of lightweight and biocompatible hollow capsules holds great promise for various advanced engineering applications. Here, we use a heterogeneously modified structure of cellulose, which on the molecular level increases the flexibility of the capsule shell, to form hollow capsules. These capsules expand in the wet state when they are exposed to an external stimulus, in the present case a decreased external pressure. The capsules were prepared by a dropwise precipitation of a propane-saturated solution of cellulose partially modified to dialcohol cellulose, dissolved in a mixture of N,N-dimethylacetamide and lithium chloride, into a non-solvent. The mechanical properties of the capsules were determined by measuring the expansion of the capsules upon a controlled decrease in external pressure. In addition, indentation measurements using atomic force microscopy were used to independently quantify the moduli of the capsule walls. The results show that the wet, modified cellulose capsules are much softer and, upon the same pressure change, expand significantly more than those made from unmodified cellulose. The greatest expansion observed for the modified capsules was 1.9 times the original volume, which corresponds to a final density of the expanded capsules of about 14 kg m⁻³. These capsules therefore hold great potential to form green and lightweight foam-like materials.

中文翻译：

由部分改性的纤维素制成的可湿膨胀胶囊

制备轻巧且生物相容的中空胶囊对于各种先进工程应用具有广阔的前景。在这里，我们使用了纤维素的异质改性结构，该结构在分子水平上增加了胶囊壳的柔韧性，从而形成了中空胶囊。当这些胶囊受到外部刺激时，它们在湿状态下膨胀，在当前情况下，外部压力降低。通过将部分改性为二元醇纤维素的丙烷的丙烷饱和溶液逐滴沉淀并溶解于N，N的混合物中来制备胶囊-二甲基乙酰胺与氯化锂成非溶剂。胶囊的机械性能是通过在受控的外部压力降低时测量胶囊的膨胀来确定的。另外，使用原子力显微镜的压痕测量被用来独立地量化胶囊壁的模量。结果表明，湿的，改性的纤维素胶囊要柔软得多，并且在相同的压力变化下，其膨胀比未改性的纤维素制成的胶囊大得多。对于改性的胶囊观察到的最大膨胀是原始体积的1.9倍，这对应于约14kg m ^-3的膨胀的胶囊的最终密度。因此，这些胶囊具有形成绿色和轻质泡沫状材料的巨大潜力。

更新日期：2020-07-20

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