Collaborative Research: Fabrication and Self-Assembly of Smart Nanoparticles

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ABSTRACT Clarkson University Clemson University0456548 0456550COLLABORATIVE RESEARCH: FABRICATION AND SELF-ASSEMBLY OFSMART NANOPARTICLESPROJECT SUMMARYIntellectual merit We propose a new approach to the fabrication of smart colloidal systems based on a combination of nanoparticles and spherical mixed polymer brushes. Mixed polymer brushes refer to monolayers of two unlikely polymers grafted to the same solid substrate. The mixed brushes grafted onto a plane of solid substrates were successfully used by the PIs to design smart and responsive surfaces which change the surface composition, interfacial energy, adhesion, adsorption, wetting behavior, etc upon external signals (solvent, pH, temperature). The mechanism of the switching/responsive behavior was shown to originate from the microphase segregation of unlikely polymers where outside conditions may strongly affect the phase segregation. In this proposal, we suggest the translation of the developed approaches into a new challenging system - spherical mixed brushes. Two unlikely polymers will be end-grafted to the same spherical nanoparticle. The spherical geometry brings new aspects to the phase segregation of the mixed brushes. Upon external stimuli, the phase separation in the spherical mixed brushes results in several characteristic morphologies: core-shell, inverse core-shell (polymers are segregated in the radial direction) and Janus-like morphology (two unlikely polymers occupy different sides of the particles). The mechanism is strongly affected by the ratio between the nanoparticles' radius and brush thickness. This new aspect will allow us to add a new parameter (particle radius) for the regulation of the response. This research will focus on the systematic study of the phase segregation mechanism in the spherical brushes in a controlled outside environment. The regulated response of the brushes will be used to regulate self-assembly of the smart particles in colloidal systems (colloidal solutions and suspensions). Formation of supra micelles upon external signal is the second target of the project. Two collaborating teams from Clarkson University and Clemson University will concentrate their expertise on the synthesis and study of the hierarchical self-assembly of spherical mixed brushes.Broader ImpactThe smart nanoparticles will allow for the modification of bulk properties as well as themodification of surface properties of materials. Development of this approach will beimportant to transform recent advances in nanoscience to industrial technologies with broadapplications from nanocomposites to drug delivery systems. Another priority of the proposedproject is the involvement of the brightest high school, undergraduate and graduate students in the modern surface and nanotechnology research. The project will result in the training of the students in the area of surface modification and characterization of nanostructured systems. Students will also greatly benefit from the collaboration between Clemson and Clarkson Universities. Moreover, they will be actively involved in the international research collaboration that is also planned in this project. Significant effort will be directed to increasethe numbers of students, especially minorities and women, who pursue advanced degrees in science and engineering.