RUI: Vibrational Properties of Dense Colloidal Suspensions with Short-Range Attractive Potential

St Joseph'S University, Philadelphia PA

Investigators

Abstract

****Technical Abstract**** Glass transition theories and the nature of the glassy state are considered to be unsolved problems in soft condensed matter physics. Colloidal suspensions are a model system for studying the nature of glasses and the glass transition. Two distinct colloidal glass states, driven by particle caging and particle bonding, have been observed in experiments and simulations. Since in colloidal suspensions the trajectories of colloidal particles can be followed in space and time using confocal microscopy, particle dynamics and structure will be studied to determine whether particle caging, bonding or both are important for the structural arrest of the system. This will be the focus of this project. Knowledge gained in this project will advance fundamental understanding about colloidal suspensions with various attractive strengths and volume fractions, and thus will further elucidate the nature of molecular glasses. Undergraduate students involved in this project will conduct research learning cutting edge experimental techniques such as sample preparation, microscopy, programming, and colloidal science. Obtained results will be widely disseminated by the undergraduate students through posters and talks at regional and national conferences, and through student-coauthored papers. Moreover, students involved in this project will gain insight into careers in science and technology. ****Non-Technical Abstract**** Complex liquids and amorphous solids such as colloidal suspensions, emulsions, liquid crystals, and polymer melts are materials encountered in every day life in a wide range of industrial branches, from the food industry to cosmetics to materials science. This experimental project explores the dynamics and structure of amorphous systems by studying suspensions of micrometer-sized particles in a liquid with varying interparticle attraction. By experimentally studying such colloidal suspensions, new results will be obtained which will confirm or refute current computer simulations and theories. Such fundamental knowledge of complex systems will aid development of new complex materials and provide insight into practical applications listed above. Furthermore, since this project includes undergraduate students, it will provide them with critical experience in cutting edge research and dissemination of obtained results through presentations at conferences and student-coauthored publications, simultaneously encouraging them towards careers in science and technology. Notably, this project will foster close professional interaction between students and the faculty mentor as an expression of cura personalis (care for the entire person), a fundamental principle of Jesuit institutions.