Bottlebrush block copolymers (BBCPs) exhibit a distinct brush-like topology, which extends their conformations and, consequently, limits chain−chain entanglement in bulk forms and in concentrated solutions. These characteristics make them attractive building blocks to create well-defined nanostructures with large periodicities by self-assembly. However, self-assembly of BBCPs into periodic nanostructures in a dilute solution has rarely been studied. Here, we report the solution self-assembly of amphiphilic BBCPs with poly(ethylene glycol) (PEG) and polystyrene (PS) as pendants attached to a polynorbornene backbone. Similar to the self-assembly of conventional linear block copolymers (BCPs), the BBCPs underwent a morphological transition from spherical micelles to vesicles as their brush ratio, defined by the weight fraction of hydrophilic PEG brushes compared to the weight of the block copolymer brushes (w PEG ), decreased. We found that the BBCPs self-assembled into inverse mesophases when the value of w PEG was below 7%. In particular, highly symmetric icosahedral cubosomes of BBCPs with internal double diamond lattices were formed when allowed to undergo self-assembly for an extended time period. This condition led us to find that new morphologies from self-assembly of BBCPs in a dilute solution, such as nanotubes and tubular networks, were analogous to the reticulated cylindrical micelles observed from the nonergodic assembly of linear BCPs. Our results suggested that BBCPs could serve a class of macromolecular building blocks to create complex nanostructures with unusual morphologies.
The
ultrasonic degradation of polynorbornene-g-polylactide
and polynorbornene-g-polystyrene brush
polymers was explored. First-order rate constants for backbone scission
were obtained for brush polymers with varying arm lengths (ranging
ca. 3–8 kDa) and backbone degrees of polymerization (ranging
ca. 78–361). Master curves, in which the rate constant trends
for all polymers converge, could be generated by accounting for the
rate enhancement from the polymer being in an extended conformation
and the contour length being equivalent to the combined length of
two arms and the backbone. Slow scission of arms from the backbone
was also observed, with first-order rate constants being dependent
on the arm length.
The interfacial topology of block copolymer cubic mesophases opens only one of two internal water channel networks for diffusion. Utilizing this topology selection, single and double diamond cubic crystalline networks...
The encoding of information by defining
the sequence of monomers
is a highly anticipated strategy for controlling the three-dimensional
structures of polymers via information-driven chain folding and self-assembly.
In this paper, we report the controlled chain folding of stereoblock
poly(lactic acid)s (PLAs) composed of two oligo(lactic acid) domains,
[DLA
n
] and [LLA
n
], constructed by using precisely defined numbers of d- and l-lactic acids, respectively. Under the crystallization-driven
self-assembly (CDSA) condition, block copolymers (BCPs) of stereoblock
PLA and poly(ethylene glycol) formed planar nanostructures having
unilamellar crystalline cores of stereoblock PLA. [DLA
n
]-[LLA
n
] stereoblocks
were folded predominantly by intramolecular stereocomplexation (SCN)
in dilute solutions in which the intermolecular interaction between
BCPs was suppressed. The thickness of the planar nanostructures was
precisely defined by the number of repeating units constituted of
[DLA
n
] and [LLA
n
] domains. The convergent synthesis of PLA permitted the addition
of a single monomer unit between the [DLA
n
] and [LLA
n
] domains, resulting in the
introduction of a desired functional group at the apex of the folded
chain. Our results demonstrate that information encoded in the form
of a monomer sequence may shape the polymer chain and guide its self-assembly
toward specific nanostructures having the desired dimensions and functions.
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