Synthesis of organic-inorganic hybrids via ozone chemistry: Synthesis, characterization and mechanical properties of polystyrene-polyetherimide ABA block copolymers
This thesis is divided in two independent parts. The work described in the first part involves the development of a new system for the synthesis of organic-inorganic hybrids utilizing ozone and silicon chemistry.
Polydimethylsiloxane proved to be resistant to ozone over 24 hr. This indicates that the Si-CH$\sb3$ group is resistant to ozone attack. Investigation of the ozonization of phenyl-containing siloxane copolymers (PSX-80) suggested that ozone attack takes place in two steps. In the first step ozone attacks and breaks the aromatic ring attached to silicon and subsequently the weakened Si-C moiety is cleaved to form the siloxane group.
Mixtures of phenylsilane with several hydrosiloxanes having variable amount of hydride content were oxidized in order to effect hybridization. Ozonization of phenylsilane (PhSiH$\sb3)$ generates the inorganic component of the hybrid material, while the organic constituent is due to the siloxane polymers. The ability to vary the hydride concentration on the polymer backbone enables the control of the inorganic content of the hybrid. The hybrid materials exhibit low surface polarity and high thermal stability which depends on the inorganic content of the material.
Application of ozonized hydrosiloxanes as coatings for cellulose paper was investigated. Contact angle and tensile testing data suggested that even the smallest amount of silicone coating dramatically affects the surface behavior and the wet strength of the cellulose paper.
In the second part of this document the mechanical properties of oriented elastomers at low temperatures are investigated. A dramatic increase, to the levels of high performance plastics, was observed in the modulus and strength of the oriented elastomers ($\sim$32 GPa, 1.2 GPa).
A polyetherimide-b-polystyrene ABA type block copolymer was synthesized and its properties were examined. The weak and brittle behavior of the copolymer indicated that a higher molecular weight soft segment (polystyrene) is necessary in order to perform tensile testing in the elongated state.