The Effect of endo/exo-Norbornene Isomer Ratio on Poly(norbornene) Optical Density at 193 nm

Abstract

The polymerization of exo- [(norbornenemethoxy)methyl]-1,1,1,3,3,3-hexafluoro-2-propanol (2) using a palladium catalyst gave a significantly higher M w polymer than the endo isomer or the 80/20 mixture of endo/exo-2. To achieve similar M w higher concentrations of formic acid chain transfer agent was needed for the exo isomer than for the 80/20 mixture. As a result, the optical density at 193 nm of the exo isomer polymer is substantially lower since less olefinic polymer end groups were formed. A subtle interplay between chain transfer mechanisms and propagation rates explains the results obtained. Isomer content in poly(2) does not affect the dissolution rate in TMAH.

Stereoselective synthesis and polymerization of Exo‐5‐trimethylsilylnorbornene

“…The permeability of the polymer obtained using Ni‐catalyst was significantly higher than that of the polymer synthesized with Pd‐system that correlates with the results of PALS measurements and nitrogen adsorption–desorption results. This is in contrast to earlier found results for addition poly(3‐trimethylsilyltricyclo[4.2.1.0]nonene‐7) (PTCNSi1), when PTCNSi1 obtained using Pd‐catalyst was shown to be more permeable . Such difference could be explained by the formation of various polymer microstructure during addition polymerization.…”

“…Norbornenes are extremely convenient monomers for the targeted design of polymer materials with desired properties owing to their availability and the capability to polymerize via different ways. Polymers from substituted norbornenes could possess various valuable properties depending on the substituent nature, such as high glass transition temperatures, optical transparency, high gas permeability, low moisture absorption, the inertness of main chains, and so on. Usually norbornenes obtaining by Diels‐Alder reaction are mixtures of exo‐ and endo‐ isomers .…”

Single‐Component Catalysts for the Vinyl‐Addition Polymerization of Norbornene and its Derivatives

“…L 3 Pd−H can reinitiate VAP of norbornene or decompose to form inactive Pd(0) complexes or palladium “black”. The generation of methylenecyclohexenyl moieties upon the VAP of norbornenes was later reported for other catalytic systems, including Ni‐ [34] and Pd‐containing [98] catalysts. In most cases, this process is uncontrolled.…”

Addition Homo‐ and Copolymerizations of Dicyclopentadiene and 5‐n‐Hexylnorbornene in the Presence of Pd‐N‐Heterocyclic Carbene Complexes

“…Norbornene and its derivatives are an unusual class of monomers that can be polymerized by various mechanisms forming polymers with different structures of main chains and properties . This feature, along with the ability to synthesize series of norbornenes with a regularly varying structure, has made these compounds attractive for the macromolecular design of polymers with desired properties and for the systematic study of the relationships “polymer structure‐properties.” Depending on the nature of the side substituents and the structure of the main chain, norbornene‐based polymers can have attractive optical properties, low moisture absorption, thermal and chemical stabilities, promising membrane characteristics, etc. Dicyclopentadiene (DCPD) is one of the most readily available norbornene derivatives, which is obtained by dimerization of cyclopentadiene—a component of light fraction of oil pyrolysis.…”