Polynorbornene derivatives

Functionalized polynorbornene derivatives, (V), prepared by Liaw et al. (4) using ring-opening metathesis polymerization exhibited strong carbazole fluorescence. Monomer emissions occurred in the near ultraviolet (UV) at approximately 380 nm and extended into the blue-violet region at 330 nm. 

To measure the antibacterial activities of amphiphilic cationic polynorbornene derivatives, they developed a slightly different method based on optical density (OD). In this method, bacteria were grown in suspensions (Escherichia coli D31 and Bacillus subtilis ATCC 8037 ) of Miieller-Hinton broth (MHB) overnight at 37 °C, diluted with fresh MHB to an OD of 0.1 at 600 nm and further diluted by a factor of 10. This suspension was mixed with different concentrations of freshly prepared polymer solutions in rm-buffered saline (pH 6.5-7.0), by serial dilution in a 96-well plate, and incubated for 6 h at 37 °C. The OD 600 nm was measured for bacteria suspensions that were incubated in the presence of a polymer solution or fm-buffered saline only. After 6 h, the MIC for 90% inhibition of growth was determined. 

Figure 3.8 Antimicrobial polynorbornene derivatives. Reproduced with permission Z.M. A1 Badri, A. Som, S. Lyon, C.F. Nelson, K. Nusslein and G.N. Tew, Biomacromolecules, 2008, 9, 2805. 2008, American Chemical Society [55]...

Fig. 5 Eight possible diads for a ( )-trans-2,3 disubstituted polynorbornene chain the X substituent is derived from the exo-position, N from the endo position in the monomer...

Antimicrobial activity of cationic ROMP polymers has therefore been assessed (18, Figure 8.9) [106,107]. Amphiphilic polynorbornene (PNBE) derivatives were generated, and the antimicrobial and hemolytic activities evaluated to maximize the selectivity of the polymers toward prokaryotic cell disruption. A minimum charge density per polymer was required for antimicrobial activity, but when... 

Introduction of proper pendant groups in monomer unit of addition polynor-bornene is the way to get polynorbornenes with desired properties. However, the appearance of substituents in norbornene molecules resulted in a decrease of their activity as monomers [220, 223]. In the case of ROMP, this effect is softened to some extent by substantial thermodynamic driving force in the process appearing as a result of opening highly strained bicyclic norbornene skeleton (see Table 1). AP is not such a thermodynamically favorable process. Therefore, in this case the introduction of side substituents, especially bulky or functional groups, led to a dramatic decrease in activity of norbornene derivatives [224-227]. Probably, this fact is one of the reasons for the limited number of publications devoted to AP of silyl substituted norbornenes. 

Polymers of Norbornenenitriles. On the basis of preliminary evaluation of the properties of various polynorbornenes, the monomer availability and the polymerization behavior, the polymers of the nitrile derivatives were considered most promising as new materials. The homopolymers of 5-norbomene-2-nitrile and 2-methyl-5-norbornene-2-nitrile and a block copolsnner of 5-nor-bornene-2-nitrile with SBR were prepared and evaluated with respect to their physical properties. The ternary system, WCls-paraldehyde-Al(isoBu)3 was used as the catalyst, which efficiently induced the polymerization at a catalyst-to-monomer ratio as low as ca. 4 x lO . ... 

The polymers generated by Ni(acac)2/MAO and other naked nickel-type catalysts are soluble in toluene and differ significantly from those derived from metallocene catalysts that are insoluble. Chemical shifts for the bridge carbon (C7) in the soluble polynorbornene were found between 33.8 and 34.3 ppm.Based on the assignment made by Al-Samak et for norbornene hydrotrimers (Figure 12), the chemical shift of 33.8 ppm belongs to mm and that of 34.2 ppm to mr and rm triads and an atactic polymer. Metallocene-based polynorbornenes show more mm triads and are more or less isotactic. Polynorbornenes synthesized by neutral nickel catalysts show in the C-NMR spectrum a peak at 35.0 ppm from C7 that indicates no substantial content of mm triads. 

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