10.1021/acssuschemeng.8b00330.s001 Xinchen Ye Xinchen Ye Kristina Junel Kristina Junel Mikael Gällstedt Mikael Gällstedt Maud Langton Maud Langton Xin-Feng Wei Xin-Feng Wei Christofer Lendel Christofer Lendel Mikael S. Hedenqvist Mikael S. Hedenqvist Protein/Protein Nanocomposite Based on Whey Protein Nanofibrils in a Whey Protein Matrix American Chemical Society 2018 hydrogen-bonded β- sheets Whey Protein Nanofibrils extent exfoliation nanocomposite films β- sheets nonfibrillar protein matrix content Tensile tests glycerol-plasticized films protein film glycerol distribution X-ray diffraction undulation Whey Protein Matrix PNF material protein nanofibrils 2018-03-15 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Protein_Protein_Nanocomposite_Based_on_Whey_Protein_Nanofibrils_in_a_Whey_Protein_Matrix/6019925 This article describes nanocomposite films with separately grown protein nanofibrils (PNFs) in a nonfibrillar protein matrix from the same protein starting material (whey). Tensile tests on the glycerol-plasticized films indicate an increased elastic modulus and a decreased extensibility with increasing content of PNFs, although the films are still ductile at the maximum PNF content (15 wt %). Infrared spectroscopy confirms that the strongly hydrogen-bonded β-sheets in the PNFs are retained in the composites. The films appear with a PNF-induced undulated upper surface. It is shown that micrometer-scale spatial variations in the glycerol distribution are not the cause of these undulations. Instead, the undulations seem to be a feature of the PNF material itself. It was also shown that, apart from plasticizing the protein film, the presence of glycerol seemed to favor to some extent exfoliation of stacked β-sheets in the proteins, as revealed by X-ray diffraction.