Grubbs Hydrophobic

Metathesis has been applied in oleochemistry for many years, but only fairly recently technical realization comes within reach [33, 34]. As typical catalysts, ruthenium carbene complexes of the Grubbs type are applied because of their very high activity (turnover numbers up to 200 000). In principle, oleochemical metathesis can be divided into two different types in self-metathesis the same fatty substrate reacts with itself and in cross-metathesis a fatty substrate reacts with, for example, a petrochemical alkene. The simplest case, the self-metathesis of methyl oleate forms 9-octadecene and dimethyl 9-octadecenedioate. The resulting diester can be used along with diols for the production of special, comparatively hydrophobic, polyesters. An interesting example of cross-metathesis is the reaction of methyl oleate with an excess of ethene, so-called ethenolysis. This provides two produds, each with a terminal double bond, 1-decene and methyl 9-decenoate (Scheme 3.3). 

Work has been performed in which the quaternary pyridinium functionality was attached to 7-oxanorbornene-5,6-exo-dicarboximide-functionalised monomers which were subsequently polymerised using a Grubbs catalyst (Grubbs catalysts are a series of transition metal carbene complexes used as catalysts for olefin metathesis). The polymer series, a-f, and quaternised polymer, a , (Figure 9.1 and Table 9.1) was designed to study the effect of the hydrophobic alkyl substituent on the antibacterial and haemolytic activities of polymers using dimethylformamide (DMF) as the solvent. 

Cross-linking of polymeric nanoparticles is a commonly used method to confer unique physical attributes including enhanced stabihty and retention of encapsulated compounds. Two distinct approaches to cross-linking ROMP-based polymeric nanoparticles have been demonstrated in the literature. The first approach, pursued by Grubbs and coworkers [85], involves the polymerization of a cinnamoyl-containing NBE monomer that undergoes [2 -l- 2] dimerization upon irradiation with ultraviolet light. A hydrophobic, cinnamoyl-modified NBE (NBE-cinn) is polymerized in one block, and a hydrophilic PEG monomer (NBE-PEG) is polymerized as the other block in order to afford an amphiphilic... 

Figure 6.23 Procedure used for the synthesis of amphiphilic, thiol-reactive biock copolymers. (I) ROMP of the hydrophobic block with Grubbs catalyst, (ii) polymerization of the second block, (iii) termination of the polymerization with an excess of ethyl vinyl ether, (Iv) coupling of hexaethylene...

Biagini and Parry [73] showed that the block copolymerization of di- and tripeptide-based NBE dicarboximide with PEG-functionalized NBE derivative using a first-generation Grubbs ruthenium initiator yielded water-compatible copolymers. The copolymers formed aggregates upon dispersion in water, and the type of aggregates (folded worms, interpenetrating networks) was directed by the specific peptide sequence rather than by the hydrophobic/hydrophilic balance [74]. 

In 1959, William Grubbs used organic cation exchange polymers in fuel cells. As shown in Fig. 1.9, the cell consists of polymer electrolyte sandwiched between platinum impregnated porous electrodes. Teflon is coated on the electrodes to make them hydrophobic. The operation temperature of PEFMC can be within 80-200°C. The low operation temperature of PEMFC offers quick start-up but platinum catalysts are required to promote the electrochemical reaction. Platinum particles are deposited very finely onto carbon powders to attain the maximum surface area. The contact between gas, electrolyte and platinum catalyst should be good for the uninterrupted function of PEFMC. 

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