Wallenberg Wood Science Center, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.
Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.
ACS Appl Mater Interfaces. 2016 May 11;8(18):11682-9. doi: 10.1021/acsami.6b00924. Epub 2016 Apr 27.
Porous materials from cellulose nanofibrils (CNFs) have been prepared using Pickering foams from aqueous dispersions. Stable wet foams were first produced using surface-modified CNFs as stabilizing particles. To better maintain the homogeneous pore structure of the foam after drying, the foams were dried in an oven on a liquid-filled porous ceramic frit. The cell structure was studied by scanning electron microscopy and liquid porosimetry, the mechanical properties were studied by compression testing, and the liquid absorption capacity was determined both with liquid porosimetry and by soaking in water. By controlling the charge density of the CNFs, it was possible to prepare dry foams with different densities, the lowest density being 6 kg m(-3), that is, a porosity of 99.6%. For a foam with a density of 200 kg m(-3), the compressive Young's modulus was 50 MPa and the energy absorption to 70% strain was 2.3 MJ m(-3). The use of chemically modified CNFs made it possible to prepare cross-linked foams with water-durable and wet-resilient properties. These foams absorbed liquid up to 34 times their own weight and were able to release this liquid under compression and to reabsorb the same amount when the pressure was released.
采用 Pickering 泡沫法从水基分散体中制备了纤维素纳米纤维（CNF）的多孔材料。首先使用表面改性的 CNF 作为稳定颗粒来制备稳定的湿泡沫。为了更好地保持泡沫干燥后的均匀孔结构，将泡沫在充满液体的多孔陶瓷滤器上的烘箱中干燥。通过扫描电子显微镜和液体孔隙率法研究了细胞结构，通过压缩试验研究了机械性能，通过液体孔隙率法和浸泡在水中确定了液体吸收能力。通过控制 CNF 的电荷密度，可以制备具有不同密度的干泡沫，最低密度为 6 kg m(-3)，即孔隙率为 99.6%。对于密度为 200 kg m(-3)的泡沫，压缩杨氏模量为 50 MPa，应变 70%时的能量吸收为 2.3 MJ m(-3)。使用化学改性的 CNF 可以制备具有耐水和湿弹性的交联泡沫。这些泡沫可以吸收自身重量 34 倍的液体，并在压缩下释放这些液体，当压力释放时，它们能够重新吸收相同量的液体。
