Polymers, among metals and ceramics, are major solid materials which are widely used in all kinds of applications. Polymers are of particular interest because they can be tailored with desirable properties. Polymer-based complexes and composites, which contain both the polymers and other components such as metal oxide/salts, are playing a more and more important role in the material fields. Such complexes and composites may display the benefits of both the polymer and other materials, endowing them with excellent functionalities for targeted applications. In this dissertation, a great deal of research was conducted to synthesize novel polymers and build polymeric complexes and composites for biomedical and aerospace applications. In chapter 3, two methods were developed and optimized to fabricate sub-micron high-performance polymer particles which were subsequently used to coat onto functional carbon fibers via electrostatic interactions, for the purpose of fabricating carbon fiber reinforced polymer composites. In chapter 4, a novel Pluronic® P85-bearing penta-block copolymer was synthesized and formed complexes with magnetite. The complexes displayed non-toxicity to cells normally but were able to selectively kill cancer cells without killing normal cells when subjected to a low-frequency alternating current magnetic field. Such results demonstrated the potential of such polymeric complexes in cancer treatment. Chapter 5 described the synthesis of several ionic graft copolymers primarily bisphosphonate-containing polymers, and the fabrication of polymer-magnetite complexes. The in-depth investigation results indicated the capability of the complexes for potential drug delivery, imaging, and other biomedical applications. Chapter 6 described additional polymer synthesis and particle or complex fabrication for potential drug delivery and imaging, as well as radiation shielding. / PHD / Polymers, metals, and ceramics are three major classes of solid materials that are used every day and everywhere. Polymers are of particular significance because they can be tailored to possess certain desirable properties, and, hence, they are playing a more and more important role as substitutes for metals and ceramics in a wide array of applications. Engineering and high-performance polymers were synthesized with excellent properties for biomedical and aerospace applications. Polymers can be fabricated into composites and complexes which contain not only polymers but also other materials, such as metal oxides/salts, carbon fibers, glass fibers, etc. When composites and complexes are made with sufficient stability, the materials may display the advantages of each component, making them more promising for specific applications. In this dissertation, effort was focused on developing versatile polymer-based complexes and composites for aerospace and biomedical applications. Chapter 3 describes the fabrication of sub-micron high-performance polymer particles by two methods and they were subsequently coated onto functional carbon fibers for making composites. Chapter 4 describes the synthesis of a novel copolymer that formed complexes with magnetite nanoparticles. The complexes were able to selectively kill cancerous cells without killing normal cells when exposed to an external magnetic field, and thus these materials have potential for cancer treatment. Chapter 5 describes the fabrication of phosphonate-bearing ionic copolymer-magnetite complexes and their potential applications in drug delivery, imaging, and other biomedical applications. Chapter 6 describes the synthesis of polymers and their corresponding complexes for potential drug delivery and imaging, as well as potential radiation shielding applications.