| Methodology was developed for the end-group modification of hyperbranched polyetherimides (HBPs). Terminating segments were prepared of A1 functionality, and used to cap a polymerization of AB2 monomers. The resulting polymers possessed end-groups of defined constitution and composition, which were subsequently shown to control physical properties such as glass transition temperature or solubility. The thermal stability of the polyetherimide core was maintained, and the methodology has proven applicable to a wide range of aryl or alkyl-ether end-group functionalities.; When cast as thick films, the end-groups dominated film stability. Lacking chain entanglements, the HBP films proved very brittle. Spin-coated thin films covered substrates more evenly, and showed a surface energy dependence with end-group functionality.; Blends of HBPs with linear polymers were also prepared, both cast from homogeneous solutions and melt-processed. When cast from solution, the HBPs exhibited interesting phase behavior at the air-interface of the film. The character and magnitude of the structures was influenced by HBP end-group, bulk phase, and the casting solvent. Spin-cast thin films reduced the influence of solvent, and indicated the importance of surface energy as the prime driving force in polymer segregation in thin films. When studied as dewetting inhibitors, HBPs were shown to both promote and inhibit dewetting, controlled by end-group functionality.; When used as a modifier for melt-processed blends, the HBP domain size was based upon end-group composition and Tg. Increasing the length of alkyl chain increased compatibility with a polyolefin matrix (PE). While no processing advantage was observed by the incorporation of HBPs, polyethylene tapes were toughened at very low loading levels. |
