Block copolymers (BCPs) have received significant attention as promising candidates for sequestering nanoparticles and fabrication of aligned nanostructures with optimal optical or electrical properties. We investigate the influence of static and dynamic thermal field on the alignment of polystyrene‐
Herein, we report the design and synthesis of a block copolymer (BCP) with a high Flory–Huggins interaction parameter to access 10 nm feature sizes for potential lithographic applications. The investigated BCP is poly[(2‐methyl‐2‐oxazoline)‐
- PAR ID:
- 10461478
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science Part A: Polymer Chemistry
- Volume:
- 57
- Issue:
- 12
- ISSN:
- 0887-624X
- Page Range / eLocation ID:
- p. 1349-1357
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract block ‐poly(methyl methacrylate) (PS‐b ‐PMMA) BCP morphology with the loading of novel poly(methyl methacrylate‐block ‐Polystyrene) (PMMA‐b ‐PS)‐grafted‐TiO2nanoparticles (BCP‐g‐TiO2). Observation of characteristics IR peaks for PMMA and PS in BCP‐g‐TiO2nanoparticles and Transmission Electron Microscopy (TEM) results of the outer coating of core nanoparticle, validate the grafting to approach in synthesizing BCP‐g‐TiO2. Here we report that under the sharp dynamic thermal field, at low loading of BCP‐g‐TiO2, there is good dispersion of nanoparticles in unidirectionally aligned BCP matrix in film interior probed by GISAXS, while, at high nanoparticle loading (~10 wt%), there is local frustration in the unidirectional alignment of the BCP matrix due to aggregation of BCP‐g‐TiO2nanoparticles. However, Grazing incidence small angle X‐ray scattering (GISAXS) shows clearly that the BCP films remain largely locally ordered at the domain scale, despite these large perturbations to long‐range ordering even at high loading level, while bringing in new TiO2functionality to the BCP films, such as UVO absorptivity or biofouling prevention, important to potential new applications of such membranes. -
ABSTRACT We demonstrate the directional alignment of perpendicular‐lamellae domains in fluorinated three‐armed star block polymer (BP) thin films using solvent vapor annealing with shear stress. The control of orientation and alignment was accomplished without any substrate surface modification. Additionally, three‐armed star poly(methyl methacrylate‐block‐styrene) [PMMA‐PS] and poly(octafluoropentyl methacrylate‐block‐styrene) were compared to their linear analogues to examine the impact of fluorine content and star architecture on self‐assembled BP feature sizes and interdomain density profiles. X‐ray reflectometry results indicated that the star BP molecular architecture increased the effective polymer segregation strength and could possibly facilitate reduced polymer domain spacings, which are useful in next‐generation nanolithographic applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
2019 , 57, 1663–1672 -
ABSTRACT Ternary block copolymer (BCP)‐homopolymer (HP) blends offer a simple method for tuning nanostructure sizes to meet application‐specific demands. Comprehensive dissipative particle dynamic (DPD) simulations were performed to study the impact of polymer interactions, molecular weight, and HP volume fraction (
) on symmetric ternary blend morphological stability and domain spacing. DPD reproduces key features of the experimental phase diagram, including lamellar domain swelling with increasingφ HP , the formation of an asymmetric bicontinuous microemulsion at a critical HP concentration , and macrophase separation with further HP addition. Simulation results matched experimental values for and lamellar swelling as a function of HP to BCP chain length ratio,φ HP . Structural analysis of blends with fixedα =N HP/N BCP but varyingφ HP confirmed that ternary blends follow the wet/dry brush model of domain swelling with the miscibility of HPs and BCPs depending onα . Longer HPs concentrate in the center of domains, boosting their swelling efficiencies compared to shorter chains. These results advance our understanding of BCP‐HP blend phase behavior and demonstrate the value of DPD for studying polymeric blends. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.α 2019 ,57 , 794–803 -
ABSTRACT The effects of incorporating metal‐binding ligands as chain extenders in polyurethane elastomers were investigated. Segmented polyurethanes based on 2 kDa poly(tetramethylene oxide) (PTMO) and 4,4‐methylenebis(cyclohexyl isocyanate) were polymerized using a two‐step process in which 2,6‐bis(1‐ethyl‐5‐(methoxymethyl)‐1H‐benzo[d]imidazol‐2‐yl)pyridine was added as a chain extender. The resulting polyurethanes were then metallated using stoichiometric amounts of Zn(II) metal salts with different counterions. The resulting metallopolymers have substantially improved Young's moduli, increased failure stress, and improved thermomechanical behavior. The materials were microphase‐separated into anisotropic hard domains within a PTMO matrix. Simultaneous small‐angle X‐ray scattering and tensile testing revealed the minority hard segment domains remain relatively intact during elongation, likely due to the strength of the metal–ligand complex. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
2019 , 57, 1744–1757 -
Abstract The structure and dynamics of polystyrene (PS)‐
b ‐poly(ethylene oxide) block copolymers (BCPs) are studied. The BCPs exhibit microphase‐separated cylindrical and lamellar morphologies. Structural dynamics are measured with X‐ray photon correlation spectroscopy in the small‐angle regime. Morphologies and domain sizes are evaluated using small‐angle X‐ray scattering (SAXS), scanning electron microscopy, and atomic force microscopy. Different solvent processing conditions are investigated. Grain sizes evaluated using SAXS are found to depend on processing only for the rubbery majority BCP. The structural relaxation times are examined as a function of PS volume fraction, temperature, morphology, and structural sizes. Well above the glass transition temperature (T g) of PS, all samples exhibit stretched autocorrelation decays and diffusive dynamics. NearT gof PS, the dynamics of all samples are anomalous with compressed autocorrelation decays and hyperdiffusive dynamics. This transition occurs at 153 °C or 1.13T gof PS. In the diffusive regime (at high temperature), structural relaxation times are dependent on the processing method. Near PST g(at low temperature), structural relaxation times scale with the PS volume fraction. Structural relaxation times do not correlate with grain size, indicating that the out‐of‐equilibrium state of PS dominates the structural dynamics of these strongly phase‐segregated BCPs.