Iso-concentration ordering kinetics of block copolymers in solution during solvent extraction using dynamic oscillatory measurements

Heinzer, Michael J.; Han, Sangil; Pople, John A.; Martin, Stephen M.; Baird, Donald G.

doi:10.1016/j.polymer.2012.05.019

Cited by 3 publications

(4 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…attain similar values. This is a typical feature of a percolating system (gel point) [37][38][39]. The percolating structure acts as a very weak reversible network leading to an enhancement of the moduli.…”

Section: Saxs Characterizationmentioning

confidence: 99%

“…Such solutions exhibit in the unperturbed state a viscos liquid-like behavior with ′′ > ′. The cross-over of ′ and ′′ is a hint of a thermoreversible gel formation with a more elastic behavior ( ′ > " [38,39]. The influence of increasing shear rate and deformation for the same system was studied by experiments with varying shear amplitude, see Figure 7.…”

Section: Saxs Characterizationmentioning

confidence: 99%

See 1 more Smart Citation

Tailoring the morphology of self-assembled block copolymer hollow fiber membranes

Radjabian

Koll

Buhr

et al. 2014

Polymer

View full text Add to dashboard Cite

Isoporous asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) hollow fiber membranes were successfully made by a dry-jet wet spinning process. Well-defined nanometer-scale pores around 20-40 nm in diameter were tailored on the top surface of the fiber above a non-ordered macroporous layer by combining block copolymer self-assembly and non-solvent induced phase separation (SNIPS). Uniformity of the surface-assembled pores and fiber cross-section morphology was improved by adjusting the solution concentration, solvent composition as well as some important spinning parameters such as bore fluid flow rate, polymer solution flow rate and air gap distance between the spinneret and the precipitation bath. The formation of the well-organized self-assembled pores is a result of the interplay of fast relaxation of the shear-induced oriented block copolymer chains, the rapid evaporation of the solvent mixture on the outer surface and solvent extraction into the bore liquid on the lumen side, and gravity force during spinning. Structural features of the block copolymer solutions were investigated by small angle X-ray scattering (SAXS) and rheological properties of the solutions were examined as well. The scattering patterns of the optimal solutions for membrane formation indicate a disordered phase which is very close to the disorder-order transition. The nanostructured surface and cross-section morphology of the membranes were characterized by 2 scanning electronic microscopy (SEM). The water flux of the membranes was measured and gas permeation was examined to test the pressure stability of the hollow fibers.

show abstract

Section: Saxs Characterizationmentioning

confidence: 99%

Section: Saxs Characterizationmentioning

confidence: 99%

Tailoring the morphology of self-assembled block copolymer hollow fiber membranes

Radjabian

Koll

Buhr

et al. 2014

Polymer

View full text Add to dashboard Cite

show abstract

“…Thin films are prepared by depositing a block polymer solution onto a substrate by spin coating or dip coating, for example, and drying to form a solid film. Typically, the film is then annealed at elevated temperature or in the presence of solvent vapor to organize the structure. − Solvent vapor annealing is more attractive than thermal annealing and provides greater flexibility in morphology control and does not cause thermal degradation. , While these annealing methods are effective, an alternative is to control the deposition and drying process so that the desired nanostructure develops directly on drying and no secondary treatment is needed. A step toward this goal is to develop a characterization tool for exploring the structure development through the thickness of a drying block polymer coating.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Microrheology of Block Copolymer Solutions

Kim

Seo

Francis³

2013

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The viscosity of poly(styrene)-b-poly(lactide) [PS-b-PLA] solutions in a neutral solvent was characterized by magnetic microrheology. The effect of polymer concentration on the viscosity of the block polymer solutions was compared with that of the PS and PLA homopolymers in the same solvent. The viscosity of PS-b-PLA solution, unlike the homopolymer solutions, showed a steep increase over a narrow concentration range. The steep rise was concomitant with microphase separation into an ordered cylindrical microstructure as determined by small-angle X-ray scattering. Hence microrheology proved effective as a means of characterizing the order-disorder transition concentration. During an in situ drying experiment, changes in local viscosity through the depth of a block copolymer solution were characterized as a function of drying time. Early in the drying process, the viscosity rose steadily and was uniform through the depth, a result consistent with steadily increasing and uniform polymer concentration. However, later in the drying process as the overall polymer concentration approached that required for microphase separation, the viscosity of the polymer solution near the free surface became an order of magnitude higher than that near the bottom of the container. The zone of high viscosity moved downward as drying proceeded, consistent with a microphase separation front.

show abstract

“…Several previous works have described many such scenarios. − The vesicle is a particularly attractive structure because of its spherical enclosed space. With applications ranging from nanoreactors, biomedical devices, or potential filling materials in micromanufacturing, − the utility of this configuration is immense. However, conventional methods of vesicle formation have three primary limitations when considered from a nanomanufacturing perspective.…”

Section: Introductionmentioning

confidence: 99%

Standalone Block Copolymer Nanoballoons: Decoupling Self-Assembly from Implementation in Nanomanufacturing

Wang

Shen

Lin

et al. 2022

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

We report a facile method to produce isolatable hollow-core elastomeric vesicles, “nanoballoons”, prepared via block copolymer self-assembly in a polymer blend. Poly(isoprene-block-dimethylsiloxane) (PI–PDMS) diblock copolymers are blended with PDMS homopolymers (h-PDMS) as a “solvent” phase to template the self-assembly of PDMS-tethered vesicles with PI walls. The walls are subsequently crosslinked to yield mechanically stabilized elastomeric vesicles. The h-PDMS inner core and matrix are separated from the vesicles by dialysis to yield the matrix-free nanoballoons. These objects, 0.3–1 μm in diameter, can be further reincorporated into a crosslinkable PDMS. Throughout the self-assembly, recovery, and reincorporation processes we apply several techniques including solvent dispersion/dynamic light scattering (DLS) measurements, transmission electron microscopy (TEM)/energy-dispersive X-ray spectroscopy (EDS), and small-angle X-ray scattering (SAXS) to provide a consilient body of evidence that the nanoballoon morphology is retained. This work presents advanced nanomanufacturing schema that illustrate the decoupling of the thermodynamic and dynamic factors that govern macromolecular self-assembly from the environment in which the self-assembled objects are deployed.

show abstract

Iso-concentration ordering kinetics of block copolymers in solution during solvent extraction using dynamic oscillatory measurements

Cited by 3 publications

References 18 publications

Tailoring the morphology of self-assembled block copolymer hollow fiber membranes

Tailoring the morphology of self-assembled block copolymer hollow fiber membranes

Magnetic Microrheology of Block Copolymer Solutions

Standalone Block Copolymer Nanoballoons: Decoupling Self-Assembly from Implementation in Nanomanufacturing

Contact Info

Product

Resources

About