Monodisperse cylindrical micelles by crystallization-driven living self-assembly

Abstract

Non-spherical nanostructures derived from soft matter and with uniform size-that is, monodisperse materials-are of particular utility and interest, but are very rare outside the biological domain. We report the controlled formation of highly monodisperse cylindrical block copolymer micelles (length dispersity < or = 1.03; length range, approximately 200 nm to 2 microm) by the use of very small (approximately 20 nm) uniform crystallite seeds that serve as initiators for the crystallization-driven living self-assembly of added block-copolymer unimers with a crystallizable, core-forming metalloblock. This process is analogous to the use of small initiator molecules in classical living polymerization reactions. The length of the nanocylinders could be precisely controlled by variation of the unimer-to-crystallite seed ratio. Samples of the highly monodisperse nanocylinders of different lengths that are accessible using this approach have been shown to exhibit distinct liquid-crystalline alignment behaviour.

Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques

“…Highly elliptical and (sphero-) cylindrical colloids are widely used in present research and may have applications in new materials [45,46]. A diverse set of elongated particles such as cylindrical micelles [47], block copolymers [48], the mosaic tobacco virus [49], and carbon nanotubes [50,51] is experimentally available. The (self-) alignment of the latter type of particles can also be used in biological cell analyses [52], and may lead to improvements in different technologies such as solar cells [53], energy storage [54], or liquid crystal displays [55].…”

Two-dimensional assemblies from crystallizable homopolymers with charged termini

“…Seeded-growth of crystallizable BCPs from 1D cylindrical seeds prepared by sonication of long, polydisperse cylinders with a crystalline core provides a recently established route to low dispersity cylindrical micelles of controlled length [18][19][20] and also complex architectures such as block comicelles, [21][22][23] branched cylindrical micelles, 24 and multi-armed micelles. 25 The key to this approach is that the core termini of the seeds remain active to the addition of further BCP unimer, leading to a process that is analogous to a living covalent polymerization of molecular monomers.…”

“…25 The key to this approach is that the core termini of the seeds remain active to the addition of further BCP unimer, leading to a process that is analogous to a living covalent polymerization of molecular monomers. 18 Successful implementation relies on the use of core-forming blocks with close crystal lattice matching. 26 Significantly, the resulting micelles are kinetically-trapped as a consequence of the crystallization of the core and the constituent BCP chains are resistant to dynamic exchange between micelles under the conditions used which would otherwise lead to substantial dispersities in length.…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…This demonstrated an analogy with a living covalent polymerisation of molecular monomers. 324 The micelles grown by this method were also shown to be stable with respect to a change in dimensions in the selective solvent at ambient temperature over a period of many months with no change in their average length or the length distribution. This implied that the micelles were kinetically-trapped in that the constituent BCP chains were resistant to significant dynamic exchange between micelles under these conditions.…”

“…323 The use of small seed micelles (generated by sonication of longer cylinders) as "initiators" led to a process that is analogous to a living covalent polymerisation of molecular monomers. 324 This process, termed "Living…”