Well-defined polymer microspheres formed by living dispersion polymerization: precisely functionalized crosslinked polymer microspheres from monomers possessing cumulated double bonds

Abstract

The precise method for synthesizing well-defined polymer microspheres via π-allylnickel-catalyzed living coordination polymerization of allene derivatives under dispersion polymerization conditions is described. The π-allylnickel-catalyzed living coordination polymerization of allene derivatives such as phenoxyallene was carried out in protic solvents such as methanol in the presence of stabilizers such as polyvinylpyrrolidone to produce polymer microspheres with a narrowly dispersed diameter distribution (D w /D n ) at a high yield. For example, polymer microspheres with a number-average diameter (D n ) of 1.10 μm and D w /D n of 1.01 were obtained at a yield of 97%; these microspheres are composed of a polymer with a controlled molecular weight (M n = 11 700) and narrow molecular weight distribution (M w /M n = 1.06). The size of the resulting polymer microspheres proved to be affected by polymerization conditions such as the initial monomer concentrations, monomer structures, polymerization media and stabilizers. Unlike conventional dispersion polymerization systems, the use of a bifunctional monomer, 1,4-diallenoxybenzene, for this living dispersion polymerization successfully produced well-defined crosslinked living polymer microspheres that exhibited high solvent tolerance. The postpolymerization of functional allene monomers in the living dispersion polymerization was also successful, resulting in functionalized polymer microspheres that could be applied in solid-phase organic synthesis and solid-supported transition metal catalysis. NPG Asia Materials (2016) 8, e307; doi:10.1038/am.2016; published online 9 September 2016 INTRODUCTION Polymer microspheres are frequently applied in scientific and industrial fields such as coatings, electronics, biomedical engineering and organic synthesis. [1][2][3][4][5][6] Precision synthesis of polymer microspheres with a regulated size, a narrow size distribution and surface functionality is very important for the further development of polymer microspheres for advanced applications. The crosslinking of polymer microspheres is also likely to be very important for achieving sufficient reagent resistance, thermal stability and good mechanical properties. 7 Among the heterogeneous polymerization techniques, dispersion polymerization is an effective method for obtaining polymer microspheres with narrowly dispersed diameter distributions. 8,9 Dispersion polymerization is defined as a heterogeneous polymerization process that starts from a homogeneous solution of all the starting materials (i.e., the monomer, initiator and stabilizer), whereas the polymer microspheres precipitate out during the progress of the polymerization. 10 Accordingly, the polymerization should be carried out in good solvents for the monomers but poor solvents for the polymers being formed. To establish precision dispersion polymerization, the living anionic polymerization of styrene was studied in hydrocarbon solvents. [11][12][13] Although this technique successfully provides narrowly dispersed polym...

Selective Ring Opening Allene Metathesis: Polymerization or Ruthenium Vinylidene Formation

“…1 They have become a staple in the modern organic chemists toolbox as a direct result of the myriad of chemical transformations made possible by their unique structure 2,3 and can be found in over 150 natural products, pharmaceuticals 4 , and even elastomers. 5 From a materials context, they are known as "carbon-rich, shape-persistent, axially chiral scaffolds". 6 Yet, their exploration in polymers is limited.…”

Selective Ring-Opening Allene Metathesis: Polymerization or Ruthenium Vinylidene Formation

“…Allenes, the simplest class of cumulenes, were discovered over a century ago . They have become a staple in the modern organic chemists toolbox as a direct result of the myriad of chemical transformations made possible by their unique structure , and can be found in over 150 natural products, pharmaceuticals, and even elastomers . From a materials context, they are known as “carbon-rich, shape-persistent, axially chiral scaffolds” .…”

100th Anniversary of Macromolecular Science Viewpoint: Polymerization of Cumulated Bonds: Isocyanates, Allenes, and Ketenes as Monomers

“…Applications of allene-derived polymers: The applications of allene-derived polymers have been understudied and only a few reports demonstrating tailored morphologies. In 2016, Yamauchi et al used coordination dispersion copolymerization of allenes to synthesize polymer microspheres, using phenoxy-substituted allene as monomer and a diallene as cross-linker . The size of the microspheres was dictated by the identity and concentration of monomer, solvents, and stabilizer (polyvinylpyrrolidone).…”

“…In 2016, Yamauchi et al used coordination dispersion copolymerization of allenes to synthesize polymer microspheres, using phenoxysubstituted allene as monomer and a diallene as cross-linker. 127 The size of the microspheres was dictated by the identity and concentration of monomer, solvents, and stabilizer (polyvinylpyrrolidone). The authors further demonstrated incorporation of a hydroxyl bearing allene comonomer that was subsequently used for postpolymerization modification, altering the hydrophilicity of the microspheres (Figure 6C).…”