Dispersion ROMP

Subsequently, the authors focused on the co-functionalization of the NBE-PEO macromonomer 18 with cleavable bioactive molecules to synthesize a range of pH-sensitive nanoparticles. Heroguez et al. [31] investigated the copolymerization of NBE in dispersion ROMP with two functionalized... 

Other studies investigated the incorporation of active molecules without a functionalization step. For example, supercritical CO2 was employed to impregnate the core of the PNBE-PEO particles with salicylic acid [35, 36]. Another variation consisted of adding a di-norbornenyl molecule 19 (Scheme 2.6) to the monomer-macromonomer mixture to obtain cross-linked nanoparticles by dispersion ROMP [37]. Reticulated polymer particles are interesting nanocarriers for the controlled release of encapsulated active substances. Raspberry-shaped nanoparticles in the size range of 300-600 nm were obtained, which arose from a double nucleation mechanism. NBE and the cross-linker were rapidly copolymerized in the first minutes of the reaction to afford a first population of highly cross-fiked particles, thereby preventing the incorporation of new active chains inside. A second population of particles was created subsequently from the... 

Aqueous perchlorate solutions, 18 274 Aqueous plugs, in microfluidics, 26 968 Aqueous polytetrafluoroethylene dispersions, 18 291 Aqueous potassium permanganate solutions, 15 597-600 Aqueous ring-opening metathesis polymerization (ROMP), 15 495... 

Polymers using the ring opening metathesis polymerization (ROMP) technique were first obtained at 1960 by Eleuterio (1,2). The patents deal with the polymerization of bicyclo[2.2.1]heptene-2, i.e., nor-bomene using a molybdenum catalyst dispersed on alumina. 

Recently, Sannino and co-workers studied the activity of Grubbs catalyst- functionalized MWCNTs by the ROMP synthesis of polynorbornene. The activities of the and 2 generation Grubbs catalysts loaded on to CNTs were found to be similar in the ROMP of 2-norbornene. The eharacterization of polynorbornene-CNT composites confirmed the good dispersibility of the nanotubes in the polymer matrix. ... 

The main advantage of the use of single-site transition metal alkylidenes in ROMP is the living character, which allows high control over molar mass, leads to narrow dispersity, and offers the chance for block copolymer formation of olefinic, even functional monomers (Fig. 3.24) otherwise not polymerizable by other methods. 

Different norbornenes and 7-oxanorbornenes were dispersed in water using cationic surfactants, yielding homopolymers and block-copolymers with narrow molecular weight distribution (PDI<1.20). It was concluded that the ROMP of these slightly water soluble monomers is living. 

ROMP is a powerful technique for the preparation of polymers with high molecular weights and low dispersity [38]. A number of computational studies on ROMP with various olefin substrates have been reported. For example, a direct comparison of the computed energies of the intermediates and transition states in the ROMP of norbornene, cyclopentene, cycloheptene, and Z-cyclooctene was reported by Cramer and Hillmyer [39] in 2012 (Table 7.1). In these reactions, a fused bicyclic metallacylobutane intermediate is formed, and the ring strain... 

In this chapter, we present a review of ROMP in dispersed media. ROMP of polymer particles by emulsion, dispersion, and suspension processes will be described. Particular attention will be devoted to the synthesis of functional nanoparticles for advanced materials. In the final part, will review nanoparticle synthesis via self-assembly of ROMP block copolymers. 

Scheme 2.5 Synthesis of particles by ROMP in dispersion using a PEO macromonomer as stabilizer.

Scheme 2.6 Monomers and PEO macromonomer polymerized by ROMP in dispersion.

Scheme 2.7 Synthesis of pH-sensitive nanopartides by ROMP in dispersion.

ROMP copolymers were also explored to disperse a platinum chromophore in a solvent in which the parent chromophore was insoluble. Slugovc et al. [75] reported the synthesis of amphiphilic triblock random copolymers containing a blue fluorescent host and a red phosphorescent guest. Deep red phosphorescence, stemming from the platinum complex used as guest component, was observed with a large Stokes shift of about 260 nm. Moreover, considerable phosphorescent quantum yields were demonstrated thanks to a suppression of the self-aggregation of the platinum complex. In a further work, the same... 

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