Diblock copolymer nano-objects are promising materials in a variety of solvents (water, alcohols, and oils). The non-polar oil solvents, however, are perhaps the most challenging medium to generate stimuli responsive nano-objects in due to their low dielectric constant. Despite this, such charged species are essential for many technological applications, such as petrochemicals, printing, electrorheological fluids, electrophoretic displays, or polymerization catalysis, for example. Through the incorporation of a polymerizable ionic monomer, we have introduced ionizable units into the stabilizer of otherwise nonionic poly(stearyl methacrylate)–poly(benzyl methacrylate) diblock copolymers synthesized in n-dodecane. The full range of expected pure morphologies (spheres, worms, and vesicles) has successfully been produced. The ionic groups interact at the surface, effectively increasing the projected area, and this shifts the critical degree of polymerization for morphology formation as compared to the nonionic case. The ionic nano-objects are also electric field responsive, undergoing counterion condensation, a characteristic of ionic species in low dielectric media. To investigate the importance of ionic groups on the self-assembly process, nano-objects were also prepared with a small fraction of ionic stabilizer chains, and these give morphology boundaries that are the same as the nonionic case but, surprisingly, have a greater electric field response than nano-objects with a fully ionic stabilizer. We anticipate that the extensive knowledge of how to synthesize non-spherical nano-objects by PISA in non-polar solvents using hydrocarbon and silicocarbon stabilizers can be directly applied to enable the production of electrophoretic nano-objects. Introducing ionic groups into non-polar solvents using diblock copolymer nano-objects offers the promise of generating interesting ionic functional nanomaterials in technologically relevant solvents.

Ionic and non-spherical diblock copolymer nano-objects in non-polar solvents

256th National Meeting (2018)

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