Chiral Polymers from Norbornenes Based on Renewable Chemical Feedstocks.

Optically active polymers are of great interest as materials for dense enantioselective membranes, as well as chiral stationary phases for gas and liquid chromatography. Combining the versatility of norbornene chemistry and the advantages of chiral natural terpenes in one molecule will open up a facile route toward the synthesis of diverse optically active polymers. Herein, we prepared a set of new chiral monomers from cis-5-norbornene-2,3-dicarboxylic anhydride and chiral alcohols of various natures. Alcohols based on cyclic terpenes ((-)-menthol, (-)-borneol and pinanol), as well as commercially available alcohols (S-(-)-2-methylbutanol-1, S-(+)-3-octanol), were used. All the synthesized monomers were successfully involved in ring-opening metathesis polymerization, affording polymers in high yields (up to 96%) and with molecular weights in the range of 1.9 × 105-5.8 × 105 (Mw). The properties of the metathesis polymers obtained were studied by TGA and DSC analysis, WAXD, and circular dichroism spectroscopy. The polymers exhibited high thermal stability and good film-forming properties. Glass transition temperatures for the prepared polymers varied from -30 °C to +139 °C and, therefore, the state of the polymers changed from rubbery to glassy. The prepared polymers represent a new attractive platform of chiral polymeric materials for enantioselective membrane separation and chiral stationary phases for chromatography.

Gas-Transport and the Dielectric Properties of Metathesis Polymer from the Ester of exo-5-Norbornenecarboxylic Acid and 1,1'-Bi-2-naphthol.

Polymers from norbornenes are of interest for applications in opto- and microelectronic (low dielectric materials, photoresists, OLEDs). Norbornenes with ester motifs are among the most readily available norbornene derivatives. However, little is known about dielectric properties and the gas-transport of polynorbornenes from such monomers. Herein, we synthesized a new metathesis polymer from exo-5-norbornenecarboxylic acid and 1,1'-bi-2-naphthol. The designed monomer was obtained via a two-step procedure in a good yield. This norbornene derivative with a rigid and a bulky binaphthyl group was successfully polymerized over the 1st generation Grubbs catalyst, affording high-molecular-weight products (Mw ≤ 1.5·106) in yields of 94-98%. The polymer is amorphous and glassy (Tg = 161 °C), and it shows good thermal stability. Unlike most, polyNBi is a classic low-permeable glassy polymer. The selectivity of polyNBi was higher than that of polyNB. Being less permeable than polyNB, polyNBi unexpectedly showed a lower value of dielectric permittivity (2.7 for polyNBi vs. 5.0 for polyNB). Therefore, the molecular design of polynorbornenes has great potential to obtain polymers with desired properties in a wide range of required characteristics. Further tuning of the gas separation efficiency can be achieved by attaching an appropriate substituent to the ester and aryl group.