Tailoring the kinetics of the photoinitiated cationic polymerization of polyoctahedral oligomeric silsesquioxane (POSS)-containing epoxy monomers
Authors
Iordanov, Liubomir
ORCID
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Other Contributors
Ryu, Chang Yeol
Bae, Chulsung
Gross, Richard A.
Bae, Chulsung
Gross, Richard A.
Issue Date
2016-08
Keywords
Chemistry
Degree
MS
Terms of Use
Attribution-NonCommercial-NoDerivs 3.0 United States
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
Full Citation
Abstract
The effect of low-viscosity reactive diluents on the UV-curing kinetics of the photoinitiated cationic polymerization of a polyhedral oligomeric silsesquioxane molecule having 8 glycidyl substituents (glycidyl POSS) was examined. This compound has many beneficial properties such hardness, scratch resistance, and high thermal stability, which make it suitable for UV coating applications. However, these properties are outweighed by a high viscosity that causes diffusion limitations, thus lowering the rate of polymerization.
3,3'-(oxybis(methylene))bis(3-ethyloxetane) (DOX), Limonene Dioxide (LDO), and α-Pinene Oxide (αPO) were all used as reactive diluents. Glycidyl POSS was copolymerized with each and the effect of weight percent (wt% ) composition and viscosity on the overall polymer reactivity was evaluated. The progress of the reaction was measured using optical pyrometry, and viscosity was measured using a cone-and-plate viscometer. Shear rheological studies were used to monitor the thermal curing behavior of glycidyl POSS with and without photoinitiator. The induction time (tind) and time at peak reaction temperature (tpeak) were both used to observe the progress of the reaction.
At any given composition of diluent, DOX performed better than either LDO or αPO; DOX needed only 20 wt% dilution to show a definite induction time, whereas LDO needed almost 50 wt% dilution to produce the same effect. Similarly, LDO showed reaction times that were at least twice as long as those of DOX when compared at the same viscosity. These results successfully demonstrate that through simple copolymerization with reactive diluents, the viscosity and reactivity of glycidyl POSS can be tailored to enhance its practical use in UV coating applications.
3,3'-(oxybis(methylene))bis(3-ethyloxetane) (DOX), Limonene Dioxide (LDO), and α-Pinene Oxide (αPO) were all used as reactive diluents. Glycidyl POSS was copolymerized with each and the effect of weight percent (wt% ) composition and viscosity on the overall polymer reactivity was evaluated. The progress of the reaction was measured using optical pyrometry, and viscosity was measured using a cone-and-plate viscometer. Shear rheological studies were used to monitor the thermal curing behavior of glycidyl POSS with and without photoinitiator. The induction time (tind) and time at peak reaction temperature (tpeak) were both used to observe the progress of the reaction.
At any given composition of diluent, DOX performed better than either LDO or αPO; DOX needed only 20 wt% dilution to show a definite induction time, whereas LDO needed almost 50 wt% dilution to produce the same effect. Similarly, LDO showed reaction times that were at least twice as long as those of DOX when compared at the same viscosity. These results successfully demonstrate that through simple copolymerization with reactive diluents, the viscosity and reactivity of glycidyl POSS can be tailored to enhance its practical use in UV coating applications.
Description
August 2016
School of Science
School of Science
Department
Dept. of Chemistry and Chemical Biology
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection
Access
CC BY-NC-ND. Users may download and share copies with attribution in accordance with a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. No commercial use or derivatives are permitted without the explicit approval of the author.