Length Control and Block-Type Architectures in Worm-like Micelles with Polyethylene Cores

Abstract

We present evidence for "living"-like behavior in the crystallization-driven self-assembly of triblock copolymers with crystallizable polyethylene middle blocks into worm-like crystalline-core micelles (CCMs). A new method of seed production is introduced utilizing the selective self-assembly of the triblock copolymers into spherical CCMs in appropriate solvents. Seeded growth of triblock copolymer unimers from these spherical CCMs results in worm-like CCMs with narrow length distributions and mean lengths that depend linearly on the applied unimer-to-seed ratio. Depending on the applied triblock copolymer, polystyrene-block-polyethylene-block-polystyrene (SES) or polystyrene-block-polyethylene-block-poly(methyl methacrylate) (SEM), well-defined worm-like CCMs with a homogeneous or patch-like corona, respectively, can be produced. In a subsequent step, these worm-like CCMs can be used as seeds for the epitaxial growth of a different polyethylene containing triblock copolymer. In this manner, ABA-type triblock co-micelles containing blocks with a homogeneous polystyrene corona and those with a patch-like polystyrene/poly(methyl methacrylate) corona were prepared. While the epitaxial growth of SEM unimers from worm-like SES CCMs with a homogeneous corona yields triblock co-micelles almost quantitatively, the addition of SES unimers to patchy SEM wCCMs results in a mixture of ABA- and AB-type block co-micelles together with residual patchy wCCMs. Following reports on self-assembled block-type architectures from polymers containing core-forming polyferrocenylsilane blocks, these structures represent the first extension of the concept to block co-micelles from purely organic block copolymers.

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.…”

Monodisperse Cylindrical Micelles and Block Comicelles of Controlled Length in Aqueous Media

“…38, [49][50][51][52][53][54][55] These developments have also provided access to new building blocks that allow the construction of a variety of complex hierarchical superstructures. [56][57][58][59][60] Herein, in an attempt to tackle the above-mentioned limitations, we report the preparation of well-defined, water-soluble cylindrical micelles of controlled length over a broad range up to 1.10 µm, with the added advantage of having a readily functionalizable coronaforming block.…”

Colour-tunable fluorescent multiblock micelles

“…Furthermore, block co-micelles with segmented structures are formed when different unimers are added sequentially to pre-existing seed initiators. CDSA phenomena have recently been reported for a wide variety of BCPs with different crystallizable core blocks [25][26][27] , and analogous processes have been used to form supramolecular heterojunctions from crystallizable hexabenzocoronene small molecules 28 .…”