Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland.
Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland.
J Colloid Interface Sci. 2019 Nov 1;555:104-114. doi: 10.1016/j.jcis.2019.07.053. Epub 2019 Jul 20.
Plant-based polysaccharides (cellulose and hemicellulose) are a very interesting option for the preparation of sustainable composite materials to replace fossil plastics, but the optimum bonding mechanism between the hard and soft components is still not well known. In this work, composite films made of cellulose nanofibrils (CNF) and various modified and unmodified polysaccharides (galactoglucomannan, GGM; hydrolyzed and oxidized guar gum, GGhydHox; and guar gum grafted with polyethylene glycol, GG-g-PEG) were characterized from the nano- to macroscopic level to better understand how the interactions between the composite components at nano/microscale affect macroscopic mechanical properties, like toughness and strength. All the polysaccharides studied adsorbed well on CNF, although with different adsorption rates, as measured by quartz crystal microbalance with dissipation monitoring (QCM-D). Direct surface and friction force experiments using the colloidal probe technique revealed that the adsorbed polysaccharides provided repulsive forces-well described by a polyelectrolyte brush model - and a moderate reduction in friction between cellulose surfaces, which may prevent CNF aggregates during composite formation and, consequently, enhance the strength of dry films. High affinity for cellulose and moderate hydration were found to be important requirements for polysaccharides to improve the mechanical properties of CNF-based composites in wet conditions. The results of this work provide fundamental information on hemicellulose-cellulose interactions and can support the development of polysaccharide-based materials for different packaging and medical applications.
植物基多糖（纤维素和半纤维素）是制备可持续复合材料以替代化石塑料的一个非常有趣的选择，但硬软组分之间的最佳结合机制仍不为人知。在这项工作中，我们从纳米到宏观层面表征了由纤维素纳米纤维（CNF）和各种改性和未改性多糖（半乳甘露聚糖，GGM；水解和氧化瓜尔胶，GGhydHox；以及接枝聚乙二醇的瓜尔胶，GG-g-PEG）制成的复合膜，以更好地理解纳米/微观复合组分之间的相互作用如何影响宏观机械性能，如韧性和强度。所有研究的多糖都很好地吸附在 CNF 上，尽管吸附速率不同，这可以通过石英晶体微天平耗散监测（QCM-D）来测量。使用胶体探针技术进行的直接表面和摩擦力实验表明，吸附的多糖提供了排斥力-很好地用聚电解质刷模型来描述-以及纤维素表面之间适度的摩擦力降低，这可能防止在复合形成过程中形成 CNF 聚集体，从而提高干膜的强度。高亲和力和适度的水合作用被发现是多糖提高湿条件下 CNF 基复合材料机械性能的重要要求。这项工作的结果提供了半纤维素-纤维素相互作用的基本信息，并可以支持开发用于不同包装和医疗应用的多糖基材料。
