Functional ROMP techniques

In the two last decades, ROMP has become an attractive and powerful route to produce functional nanoparticles for advanced materials. This unbelievable development has been made possible thanks to the advent of a new class of ruthenium catalysts tolerant of protic functions and yet highly active. Furthermore, the living behavior of the ROMP technique allowed the formation of polymeric nanostructures of controlled morphologies and dimensions. 

PS-fr-PBd) star-block copolymers were synthesized by the macromonomer technique in combination with anionic polymerization and ROMP [ 158], following the procedure outlined in Scheme 83. The macromonomers were prepared with two different methods. In the first the living diblock copolymer was reacted with ethylene oxide to reduce the nucleophihcity of the living end followed by termination with 5-carbonyl chloride bicycle (2.2.1) hept-2-ene, while in the second method the functional initiator 5-lithiomethyl bicycle... 

Support materials for solid phase extraction (SPE) and for chromatographic techniques have been prepared by ROMP. pH-stable high capacity stationary phases have been prepared by copolymerization of functional monomers with a suitable crosslinking agent, with precipitation polymerization techniques. 

Olefin metathesis is also a highly versatile technique for the synthesis of polymers from renewable resources. In this respect, especially ADMET polymerization and ROMP have been used to prepare macromolecules starting from fatty acid precursors due to their inherent double-bond functionality. Nevertheless, also other feedstock and methods have been applied, as will be reviewed within this section. 

A straightforward transformation technique was presented to convert from ROMP to hving anionic polymerization of unsaturated monomers. This employed a functional terminating agent to add a styryl group to the end of the ROMP chain the latter was then metallated to yield an active site for anionic polymerization. Both, PCP-b-PSt and PNB-b-PSt block copolymers were successfully synthesized in this way (Scheme 11.35) [146]. 

It has been demonstrated that ROMP represents a highly versatile tool in the preparation and modification of functional polymer supports. The use of well-defined initiators allows the highly reproducible preparation of tailor-made materials in particular in terms of functionalization. Various polymerization techniques such as precipitation- and graft-polymerization may be applied. In due consequence, the use of suitable polymerizable ligands allows the synthesis of well-defined heterogeneous supports. 

To expand the variety of monomers available for polymerization and to increase the range of copolymer and nanoparticle architectures, attention has turned toward the development of methods whereby multiple polymerization techniques can be utilized to generate unique and functionally diverse materials. The grafting-from (Figure 6.29) approaches to ROMP-based micellar... 

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