The proposed work is of a fundamental nature, and includes the synthesis of intricate nanostructures and investigation of their supramolecular assembly behaviors and the properties of the resulting complex morphologies. Combinations of controlled radical polymerizations and ring opening polymerizations will be used to prepare linear triblock terpolymers and molecular brush triblock terpolymers. Each polymer topology will include at least one semi-crystalline polymer component and the overall nanostructures will be amphiphilic. The differences that occur during their supramolecular assembly in water will be explored. A significant effort will be directed toward determination of the effects of molecular topology on molecular chain packing and overall properties, with the assemblies being stabilized by crosslinking within selective domains, and with portions of the nanostructures being excavated. By this process, roles of nanoconfinement and covalent attachment between polymer chains and crosslinked network surfaces will be probed by the crystallization and melting transition characteristics. Host-guest behaviors will also be investigated, with one target being organic-inorganic hybrid materials that utilize the complex organic polymer morphology as a shell layer for packaging small molecule guests and magnetic inorganic cores to facilitate magnetic recovery. Characterization studies will include standard spectroscopic techniques to determine the compositions (nuclear magnetic resonance, infrared, ultraviolet-visible), measurement of dimensions and internal morphologies (dynamic light scattering, atomic force microscopy, transmission electron microscopy, small angle neutron scattering, small angle x-ray scattering), analysis of the thermal properties (differential scanning calorimetry and thermogravimetric analysis), evaluation of the nanoparticle mechanical properties (quartz crystal microbalance with dissipation monitoring (QCM-D)), and host-guest behaviors (UV-vis, high performance liquid chromatography, QCM-D).
The supramolecular assembly of linear block copolymers is leading to high performance materials, for instance tough plastics, or nanoscopic devices for medical imaging and therapy. The new frontier will involve the construction of complex materials from polymers of higher structure. The proposed investigation, of the effects of the compositions, sizes, shapes and architectures of synthetic polymers on their controlled aggregation in water, extends the fundamental knowledge of molecular assembly processes and is expected to lead to nanoscopic materials for advanced performance in applications that will solve real-world problems. An initial target will be optimized organic polymer coatings surrounding magnetic nanoparticles, to serve as high capacity materials for sequestration-based capture and magnetic-based recovery of pollutants in the environment. Many other applications can be anticipated. The primary technical outcomes and broader impacts of the proposed work will be (1) diverse and extensive education, training and recruiting of the next generation of chemists, who gain expertise in synthetic organic/polymer chemistry, with specialty in materials science and engineering, (2) advances in synthetic polymer chemistry techniques, and (3) creation of novel materials that have the potential to positively impact society. The breadth and depth of knowledge and expertise will be extensive and cross disciplinary. Broad-based educational activities, at all levels, including the development of polymer science courses for chemists and engineers at Texas A&M University, and web-based distance-taught courses on polymer chemistry and applications of nanostructured materials, will be continued throughout the four years of this grant support.