Structure of nanoparticles embedded in micellar polycrystals

We investigate by scattering techniques the structure of water-based soft composite materials comprising a crystal made of Pluronic block-copolymer micelles arranged in a face-centered cubic lattice and a small amount (at most 2% by volume) of silica nanoparticles, of size comparable to that of the micelles. The copolymer is thermosensitive: it is hydrophilic and fully dissolved in water at low temperature (T ~ 0{\deg}C), and self-assembles into micelles at room temperature, where the block-copolymer is amphiphilic. We use contrast matching small-angle neuron scattering experiments to probe independently the structure of the nanoparticles and that of the polymer. We find that the nanoparticles do not perturb the crystalline order. In addition, a structure peak is measured for the silica nanoparticles dispersed in the polycrystalline samples. This implies that the samples are spatially heterogeneous and comprise, without macroscopic phase separation, silica-poor and silica-rich regions. We show that the nanoparticle concentration in the silica-rich regions is about tenfold the average concentration. These regions are grain boundaries between crystallites, where nanoparticles concentrate, as shown by static light scattering and by light microscopy imaging of the samples. We show that the temperature rate at which the sample is prepared strongly influence the segregation of the nanoparticles in the grain-boundaries.Comment: accepted for publication in Langmui

Food Engineering at Multiple Scales:Case Studies, Challenges and the Future—A European Perspective

Abstract A selection of Food Engineering research including food structure engineering, novel emulsification processes, liquid and dry fractionation, Food Engineering challenges and research with comments on European Food Engineering education is covered. Food structure engineering is discussed by using structure formation infreezing and dehydration processes as examples for mixing of water as powder and encapsulation and protection ofsensitive active components. Furthermore, a strength parameter is defined for the quantification of material properties in dehydration and storage. Methods to produce uniform emulsion droplets in membrane emulsification are presented as well as the use of whey protein fibrils in layerby-layer interface engineering for encapsulates. Emulsion particles may also be produced to act as multiple reactors for food applications. Future Food Engineering must provide solutions for sustainable food systems and provide technologies allowing energy and water efficiency as well as waste recycling. Dry fractionation provides a novel solution for an energy and water saving separation process applicable to protein purification. Magnetic separation of particles advances protein recovery from wastewater streams. Food Engineering research is moving toward manufacturing of tailor-made foods, sustainable use of resources and research at disciplinary interfaces. Modern food engineers contribute to innovations in food processing methods and utilization of structure–property relationships and reverse engineering principles for systematic use of information of consumer needs to process innovation. Food structure engineering, emulsion engineering, micro- and nanotechnologies, and sustainability of food processing are examples of significant areas of Food Engineering research and innovation. These areas will contribute to future FoodEngineering and novel food processes to be adapted by the food industry, including process and product development to achieve improvements in public health and quality of life. Food Engineering skills and real industry problem solving as part of academic programs must show increasing visibility besides emphasized training in communication and other soft skills