Polymer nanocomposites can be used in a variety of areas such as coating, medical implants, aerospace and textiles. Certain nanoparticles (e.g., carbon nanotubes (CNTs), clay, metal, and graphene) are also used as reinforcement in a new class of polymer nanocomposites with enhanced properties compared to conventional composites. For example, CNTs and (multilayer) graphene can be used as additives to change the polymer's mechanical and electrical properties. The polymer composite can then be extruded into threads that can be used in textiles. Hence, smart textiles can be achieved if one can manufacture polymeric threads with desired properties.
Present manufacturing methods to not produce polymeric threads with optimal properties. For example, threads that have been produced to date are not as strong as is expected from theoretical calculations, nor do they conduct electricity with the expected efficiency. A huge amount of experimental and theoretical research is therefore being conducted in this field. This is because there are a large range of parameters that affect the properties of the composite. Examples of these parameters are the length, chirality, dispersion and alignment of the CNTs and the viscosity of the polymer matrix.
Computer simulations complement experiment by deepening our understanding of the way that additives change the nanocomposite properties. We are performing molecular-scale calculations in order to understand the additive-additive and additive-polymer interactions, in an effort to understand these interactions and to identify ways to modify these interactions in order to optimise the properties of the textile threads. Our research focuses on single wall carbon nanotubes (SWNTs) added to different polymers such as polyethylene (PE) and polyvinylidene fluoride (PVDF). The figures below show the change in energy when pulling a SWNT out of a PVDF matrix (the different graphs are from the different ways of pulling the SWNT out of the polymer). This change in energy is then used to calculate the shear stress, which is a measure of the strength of adhesion between the SWNT and the polymer. It is believed that strong adhesion is needed for the SWNT to strengthen the composite material.
This research, which is done in collaboration with experiment, is funded by the Swedish Foundation for Strategic Research and The Swedish Research Council.