Lateral Growth of 1D Core-Crystalline Micelles upon Annealing in Solution

Guerin, Gérald; Rupar, Paul A.; Molev, Gregory; Manners, Ian; Jinnai, Hiroshi; Winnik, Mitchell A.

doi:10.1021/acs.macromol.6b01487

Cited by 28 publications

(39 citation statements)

References 77 publications

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“…We have shown in a previous publication 44 that the PFS core of micelles prepared by crystallization-driven self-assembly (CDSA) can be pictured as a crystalline layer sandwiched between two layers of PFS in the amorphous state, in which each amorphous layer contains α repeat units per fold. We can thus modify the equation of the free energy of a crystalline block 45 to account for these amorphous layers: where ε 1 is the energy of a unit in the crystalline state, n core , the number of folds per block, N core , the number of units of the core forming block, and δ ε , the excess energy between an amorphous and a crystalline unit.…”

Section: Resultsmentioning

confidence: 99%

Explosive dissolution and trapping of block copolymer seed crystallites

et al. 2018

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Enhanced control over crystallization-driven self-assembly (CDSA) of coil-crystalline block copolymers has led to the formation of intricate structures with well-defined morphology and dimensions. While approaches to build those sophisticated structures may strongly differ from each other, they all share a key cornerstone: a polymer crystallite. Here we report a trapping technique that enables tracking of the change in length of one-dimensional (1D) polymer crystallites as they are annealed in solution at different temperatures. Using the similarities between 1D polymeric micelles and bottle-brush polymers, we developed a model explaining how the dissolving crystallites reach a critical size independent of the annealing temperature, and then explode in a cooperative process involving the remaining polymer chains of the crystallites. This model also allows us to demonstrate the role of the distribution in seed core crystallinity on the dissolution of the crystallites.

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Section: Resultsmentioning

confidence: 99%

Explosive dissolution and trapping of block copolymer seed crystallites

et al. 2018

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“…The value of σ can be evaluated (eq. 2) as the ratio of Nagg/L (determined by SLS) to the circumference of the cylinder 38 (estimated from the mean width of the micelle core (Wcore  13 nm) in TEM images, Figure S9).…”

Section: Andmentioning

confidence: 99%

Monitoring Collapse of Uniform Cylindrical Brushes with a Thermoresponsive Corona in Water

Zhou

et al. 2018

ACS Macro Lett.

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We generated rod-like micelles of uniform length by living crystallization-driven selfassembly of a polyferrocenylsilane (PFS) block copolymer PFS26-b-POEGMA163 in a methanolethanol mixture and then transferred these micelles to water. The corona chains consisted of poly(oligoethyleneglycol methacrylate) that had a lower critical solution temperature (LCST) of 40.5 C in water. We used a combination of static (SLS) and dynamic (DLS) multiangle light scattering to determine the dimensions of these cylindrical brush micelles in solution. Measurements carried out in dilute solution in water over a series of temperatures from 23 to 50 C showed that the collapse transition was broad and continuous, both upon heating and cooling. This response is different from the collapse transition of POEGMA163 homopolymer in water, which occurs over a very narrow temperature range. Thus we show that the collapse transition of a cylindrical brush has important features in common with the collapse of a brush of thermoresponsive polymers on a planar surface.

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“…For typical platelet homopolymer crystals, the platelets become thicker and the degree of crystallinity increases 36,37. [ref added] Less is known about core-crystalline micelles, but we recently examined one sample of PFS65-b-PI637 micelle fragments annealed in decane at 75 C 38. Here we found an increase in the number of BCP molecules per nm of micelle length, and TEM tomography measurements showed that the micelle core became wider and more rectangular.…”

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confidence: 86%

NMR Study of the Dissolution of Core-Crystalline Micelles

Pichugin

Cruz

et al. 2018

Macromolecules

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The core-crystalline micelles formed by block copolymer (BCP) poly(ferrocenyldimethylsilane)block-poly(isoprene) (PFS-b-PI) underwent self-seeding in solution when heated above 17-10 2 dissolution temperature. Variable temperature (VT) proton (1 H) NMR and diffusion-ordered pulsed-gradient spin-echo (DOSY) NMR were used to monitor the behavior of micelles that dissolved as a function of temperature. We examined a sample of micelle fragments of PFS65-b-PI637 characterized by Ln = 39 nm, Lw/Ln = 1.13. The PI corona had high mobility and gave a 1 H NMR signal in both micellar and unimers forms. Whereas the PFS component could only be detected for the dissolved unimers. We found from 1 H NMR that all the BCP molecules were incorporated into the micelles at temperatures up to and including 50 C. Both PFS and PI resonances could be detected between 70 and 100 C, and the integration ratio of the PFS-to-PI peaks increased with temperature. The DOSY NMR measured the self-diffusion coefficients (Ds) for the micelle fragments and unimers at these temperatures. The hydrodynamic radii (Rh) for these species were calculated from Ds using Stokes-Einstein equation. The PFS signals gave Rh values in the range of 5 to 6 nm at temperatures between 80 to 100 C, consistent with unimer diffusion. PI signals were fitted into a single exponential decay at 25 C with Rh = 38 nm characteristic of the micelle fragments, and at 90, 95, and 100C with Rh  6 nm, corresponding to unimer. At intermediate temperatures (70 to 85 C), PI signals were fitted to a sum of two exponential terms, consistent with a fast diffusing species and a slow diffusing species. Interestingly we noticed that the size of the micelle fragments at elevated temperatures (80, 85 C) was sensitive to sample history, with smaller fragments obtained for samples heated quickly to the measurement temperature while samples subjected to prolonged annealing showed much smaller reduction in size.

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Lateral Growth of 1D Core-Crystalline Micelles upon Annealing in Solution

Cited by 28 publications

References 77 publications

Explosive dissolution and trapping of block copolymer seed crystallites

Explosive dissolution and trapping of block copolymer seed crystallites

Monitoring Collapse of Uniform Cylindrical Brushes with a Thermoresponsive Corona in Water

NMR Study of the Dissolution of Core-Crystalline Micelles

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