Model organic -inorganic hybrid copolymers based on polyhedral oligomeric silsesquioxane
Hybrid organic-inorganic materials is a new class of materials having important technological potential. In this thesis, Polyhedral Oligomeric Silsesquioxane (POSS) is used as an inorganic building block which is tethered to an organic polymer. The influence of POSS on the thermal properties as well as the morphology of the final hybrid is the main focus of this work. Different polymerization chemistries were utilized to incorporate POSS into an organic polymer.
Cyclooctadiene was copolymerized with CpPOSS norbornene via Ring-Opening Metathesis Polymerization. The poly(butadiene-r-POSS) series showed lamellae formation after film casting for POSS loading higher than 30 wt%. IbuPOSS-NCO was then attached to a series of well-defined alcohol-terminated polystyrene (PSOH). The alcohol-terminated polystyrene were synthesized by the anionic polymerization of styrene, terminating the reaction with the endcapping of the living polymer by ethylene oxide, which enabled precise control over the molecular weight and the polydispersity (PDI<1.1). Increased thermal resistance was observed upon POSS addition to the PSOH series. Block copolymers of polystyrene and poly(HEMA-POSS) were then synthesized. A series of poly(styrene- b-HEMA) were first synthesized by anionic polymerization under high vacuum and POSS-NCO was reacted with the pendant alcohol of the HEMA block. By varying the volume fraction of each block, lamellar and cylindrical morphologies could be obtained. Long range order was observed by Small Angle X-ray Scattering in the samples having a lamellar morphology. Film casting provided orientation of the lamellae parallel to the surface of the beaker.
A manifold for the safe polymerization of ethylene oxide and butadiene was designed. A diblock copolymer of poly(butadiene-b-ethylene oxide) was synthesized to show the versatility of the manifold.