127524-37-2Relevant academic research and scientific papers
Effect of Segmental Configuration on Properties of n-Propyl-Bridged Polycyanurate Networks
Guenthner, Andrew J.,Harvey, Benjamin G.,Chafin, Andrew P.,Davis, Matthew C.,Zavala, Jacob J.,Lamison, Kevin R.,Reams, Josiah T.,Ghiassi, Kamran B.,Mabry, Joseph M.
, p. 4887 - 4896 (2017)
The effect of the chemical configuration of network segments on the physical properties, cure properties, mechanical performance, and chemical stability of polycyanurate networks was investigated via synthesis, network formation, and characterization of an isomeric series of n-propyl-bridged cyanate ester monomers. Configurations that provide cyanurate oxygen atoms with either nearby methyl groups or nearby bridge groups exhibited decreased moisture uptake by up to 50%, along with a roughly 20-40 °C reduction in the loss in glass transition temperatures due to hydrolysis, for networks immersed in 85 °C water for 96 h. In ortho,para-linked aryl cyanates, dry glass transition temperatures of cured networks were reduced compared to analogous para,para-linked networks by only about 10 °C, compared to a reduction of 30 °C in ortho-methylated cyanate ester networks, leading to higher wet glass transition temperatures in the ortho,para-linked networks. Neither methyl groups nor bridge groups in a position ortho to the reactive cyanate ester groups prevented the creation of networks with >99% conversion at cure temperatures of 230 °C. Networks with placement of methyl groups in a position ortho to the cyanate ester exhibited char yields in nitrogen at 600 °C of 46-47% compared to 43% for networks with methyl groups in the corresponding meta position, regardless of whether a sterically hindered environment was present around the cyanurate oxygen. These results illustrate the manner in which the chemical configuration around reactive groups can substantially modify the properties of networks even when the number density and type of reactive group present do not change.
Effects of o -methoxy groups on the properties and thermal stability of renewable high-temperature cyanate ester resins
Harvey, Benjamin G.,Guenthner, Andrew J.,Lai, William W.,Meylemans, Heather A.,Davis, Matthew C.,Cambrea, Lee R.,Reams, Josiah T.,Lamison, Kevin R.
, p. 3173 - 3179 (2015/06/08)
Renewable phenols derived from biomass sources often contain methoxy groups that alter the properties of derivative polymers. To evaluate the impact of o-methoxy groups on the performance characteristics of cyanate ester resins, three bisphenols derived from the renewable phenol creosol were deoxygenated by conversion to ditriflates followed by palladium-catalyzed elimination and hydrolysis of the methoxy groups. The deoxygenated bisphenols were then converted to the following cyanate ester resins: bis(4-cyanato-2-methylphenyl)methane (16), 4,4′-(ethane-1,1′-diyl)bis(1-cyanato-3-methylbenzene) (17), and 4,4′-(propane-1,1′-diyl)bis(1-cyanato-3-methylbenzene) (18). The physical properties, cure chemistry, and thermal stability of these resins were evaluated and compared to those of cyanate esters derived from the oxygenated bisphenols. 16 and 18 had melting points 37 and >95 °C lower, respectively, than the oxygenated versions, while 17 had a melting point 14 °C higher. The Tgs of thermosets generated from the deoxygenated resins ranged from 267 to 283 °C, up to 30 °C higher than the oxygenated resins, while the onset of thermal degradation was 50-80 °C higher. The deoxygenated resins also exhibited water uptakes up to 43% lower and wet Tgs up to 37 °C higher than the oxygenated resins. TGA-FTIR of thermoset networks derived from 16-18 revealed a different decomposition mechanism compared to the oxygenated resins. Instead of a low-temperature pathway that resulted in the evolution of phenolic compounds, 16-18 had significantly higher char yields and decomposed via evolution of small molecules including isocyanic acid, CH4, CO2, and NH3.
