Multi-Scale Characterisation of Interactions between Cellulose Interfaces and Polymers

子项目的目的是更好地理解和更好地控制聚合物与纸纤维的结合。包装应用的一个重要研究方法是在聚合物的帮助下使纸张功能化，从而赋予它们新的或改进的性能，例如增加的湿拉伸强度和更好的传输性能。挑战在于通过化学吸附或物理吸附实现聚合物与纸张的长期稳定结合，同时保持其膨胀能力。为了更好地理解和控制不同聚合物系统在纸纤维界面上的固定作用及其对纸性能的影响，在较小长度尺度上进行精确的研究是特别必要的。在本项目中，研究了聚合物在不同小长度尺度（nm -一些µm）上的粘附介导功能。由于许多用于界面表征的方法（椭圆偏振法，原子力显微镜，反射法）需要一个平面界面，因此在第一个资助期制备了纤维素的水稳定平面模型表面，它在化学上模仿纸纤维表面。在第二个资助期，将更加着重于模型表面的不同粗糙度和地形差异（孔隙、定向结构），以便模拟纤维的不同表面结构。为此，将在平面基底上生产微晶纤维素（MCC）、纤维素纤维（纳米纤化纤维素，NFC）和三甲基硅基纤维素（TMSC）薄膜。进一步了解聚合物与纤维素表面的结构、膨胀行为和力学性能之间的关系。除了在水中的膨胀性外，还研究了离子液体中的膨胀性（C1）。下一步，聚合物在纤维交叉点的积累及其对纤维交叉点机械行为的影响将得到更好的理解（B1, B3）。为此，我们扩展了模型系统，将直径为几微米的纸纤维吸附到纤维素表面，并通过原子力显微镜研究纸纤维附近的聚合物吸附。在这种情况下，应了解和控制纸纤维的取向对聚合物结合的影响，同时聚合物的迁移率。除了A3中的聚合物外，还将使用我们课题组生产的聚合物微凝胶颗粒。软微凝胶颗粒具有很强的粘附性，因此具有纤维粘合效果。这些微凝胶会对温度和pH值等外界刺激产生反应，并将长期用于制造具有传感器特性的纸张。除了聚合物，多肽的结合也要用C2来研究。

The aim of the sub-project is a better understanding and better control of the binding of polymers to paper fibres. An important research approach of the package application is to functionalise papers with the help of polymers and thus impart new or improved properties to them, such as increased wet tensile strength and better transport properties. The challenge is to achieve a long-term stable bonding of the polymers to the paper via chemisorption or physisorption while maintaining the swelling capacity. In order to better understand and control the immobilisation of different polymer systems at the interface of the paper fibre and the influence on the properties of paper, precise investigations on smaller length scales are particularly necessary. In the present project, the adhesion-mediating function of polymers is investigated on different small length scales (nm - some µm). Since many methods (ellipsometry, AFM, reflectometry) for interface characterisation require a planar interface, water-stable planar model surfaces of cellulose, which chemically imitate a paper fibre surface, were prepared in the first funding period. In the second funding period, the focus will be placed even more strongly on different roughness and topography differences (pores, oriented structuring) of the model surface in order to simulate different surface structures of fibres. For this purpose, thin films of microcrystalline cellulose (MCC), cellulose fibres (nanofibrillated cellulose, NFC) and trimethylsilyl cellulose (TMSC) will be produced on planar substrates. Furthermore, the relationship between the structure, swelling behaviour and mechanical properties of polymers and cellulose surface will be understood. In addition to swellability in water, swelling in ionic liquids is also investigated (C1). In a next step, polymer accumulation at the fibre crossing points and its effect on the mechanical behaviour of the fibre crossing points is to be better understood (B1, B3). For this purpose, the model system is extended by adsorbing a paper fibre (diameter: a few µm) onto the cellulose surface and investigating the polymer adsorption in the vicinity of the paper fibre by means of atomic force microscopy. In this context, the influence of the orientation of the paper fibres on the polymer binding with simultaneous mobility of the polymers shall be understood and controlled.In addition to the polymers from A3, the polymer microgel particles produced in our research group will be used. The soft microgel particles are strongly adhesive and therefore have a fibre-bonding effect. These microgels react to external stimuli such as temperature and pH value and are to be used in the long term to build up papers with sensor properties. In addition to polymers, the binding of peptides is also to be investigated with C2.