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Ring -opening metathesis polymerization of organic -inorganic thermosets and processable shape memory polymers
Abstract
The development of functional group tolerant ruthenium based ring-opening metathesis polymerization (ROMP) catalysts allows for the synthesis of a broad range of cyclic olefin based polymers. Highly robust ruthenium carbene catalysts allow for the ROMP of novel polymers at ambient conditions, that were not possible by previous organometallic catalysis. This research investigated the synthesis of crosslinked polyolefins by ROMP using ruthenium carbene catalysts. Specifically, polydicyclopentadiene (PDCPD) organic-inorganic copolymers were synthesized. An ultrasonic spectroscopy technique was utilized to quantify the reaction kinetics of the ROMP of dicyclopentadiene (DCPD) catalyzed by two different ruthenium catalysts. A reaction cell that held the reactants in a plane strain geometry, allowed the changes in density, acoustic velocity, acoustic modulus, and waveform attenuation to be accurately measured. It was determined that kinetic data for the crosslinking reaction could be calculated from the ultrasonic spectroscopy data. With the ability to measure the crosslinking kinetics of PDCPD homopolymer, PDCPD nanocomposites were prepared by copolymerization of DCPD and polyhedral oligomeric silsesquioxanes (POSS). The affects of the POSS functionality and the organic periphery on morphology were investigated. It was found that both the organic periphery and functionality of POSS could affect the morphology of the copolymer. Additionally, the affects of POSS functionality, on the physical and mechanical properties of the copolymer were evaluated. The thermal transitions and mechanical properties of the POSS copolymers decreased regardless of POSS functionality. Therefore, POSS acts much like a plasticizer in conventional thermosets. Additionally, POSS was found to decrease the dielectric constant of the copolymer. The dielectric constant could be further decreased by selectively degrading POSS from the matrix. A final aspect of the project utilized the catalysts' functional group tolerance to synthesize polymers containing reversible or physical crosslinks. These polymers possess the inherent shape memory characteristics of chemically crosslinked shape memory polymers and the processability of thermoplastics. Overall, this research advances our understanding of the utility of ruthenium catalyzed ROMP in thermoset polymerization through the creation of novel materials.
Subject Area
Polymers
Recommended Citation
Constable, Gregory S, "Ring -opening metathesis polymerization of organic -inorganic thermosets and processable shape memory polymers" (2004). Doctoral Dissertations Available from Proquest. AAI3152683.
https://scholarworks.umass.edu/dissertations/AAI3152683