skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • A rheometry method to assess the evaporation‐induced mechanical strength development of polymer solutions used for membrane applications
Title: A rheometry method to assess the evaporation‐induced mechanical strength development of polymer solutions used for membrane applications
ABSTRACT Rotational and oscillatory shear rheometry were used to quantify the flow behavior under minimal and significant solvent evaporation conditions for polymer solutions used to fabricate isoporous asymmetric membranes by the self‐assembly and non‐solvent induced phase separation (SNIPS) method. Three different A‐B‐C triblock terpolymer chemistries of similar molar mass were evaluated: polyisoprene‐b‐polystyrene‐b‐poly(4‐vinylpyridine) (ISV); polyisoprene‐b‐polystyrene‐b‐poly(N,N‐dimethylacrylamide) (ISD); and polyisoprene‐b‐polystyrene‐b‐poly(tert‐butyl methacrylate) (ISB). Solvent evaporation resulted in the formation of a viscoelastic film typical of asymmetric membranes. Solution viscosity and film viscoelasticity were strongly dependent on the chemical structure of the triblock terpolymer molecules. A hierarchical magnitude (ISV > ISB > ISD) was observed for both properties, with ISV solutions displaying the greatest solution viscosity, fastest film strength development, and greatest strength magnitude. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47038.  more » « less
Award ID(s):
1707836
PAR ID:
10073714
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Journal of Applied Polymer Science
Volume:
136
Issue:
6
ISSN:
0021-8995
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Macromolecular Chemistry and Physics)
    Abstract Materials combining an asymmetric pore structure with mesopores everywhere enable high surface area accessibility and fast transport, making them attractive for e.g., energy conversion and storage applications. Block copolymer (BCP)/inorganic precursor co‐assembly combined with non‐solvent induced phase separation (NIPS) provides a route to materials in which a mesoporous top surface layer merges into an asymmetric support with graded porosity along the film normal and mesopores throughout. Here, the co‐assembly and non‐solvent‐induced phase separation (CNIPS) of poly(isoprene)‐b‐poly(styrene)‐b‐poly(4‐vinylpyridine) (ISV) triblock terpolymer and titanium dioxide (TiO2) sol‐gel nanoparticlesare reported. Heat‐treatment in air results in free‐standing asymmetric porous TiO2. Further thermal processing in ammonia results in free‐standing asymmetric porous titanium nitride (TiN). processing changes alter structural membrane characteristics is demonstrated. Changing the CNIPS evaporation time results in various membrane cross‐sections ( finger‐like to sponge‐like). Oxide and nitride material composition, crystallinity, and porosity are tuned by varying thermal processing conditions. Finally, thermal processing condition effects are probed on phase‐pure asymmetric nitride membrane behavior using cyclic voltammetry to elucidate their influence, e.g., on specific capacitance. Results provide further insights into improving asymmetric and porous materials for applications including energy conversion and storage, separation, and catalysis and motivate a further expansion of CNIPS to other (in)organic materials. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Polymer Chemistry)
    In this work, we designed and fabricated a nanoscopic sugar-based magnetic hybrid material that is capable of tackling environmental pollution posed by marine oil spills, while minimizing potential secondary problems that may occur from microplastic contamination. These readily-defined magnetic nanocomposites were constructed through co-assembly of magnetic iron oxide nanoparticles (MIONs) and a degradable amphiphilic polymer, poly(ethylene glycol)- b -dopamine-functionalized poly(ethyl propargyl glucose carbonate)- b -poly(ethyl glucose carbonate), PEG- b -PGC[(EPC-MPA)- co -(EPC-DOPA)]- b -PGC(EC), driven by supramolecular co-assembly in water with enhanced interactions provided via complexation between dopamine and MIONs. The composite nanoscopic assemblies possessed a pseudo -micellar structure, with MIONs trapped within the polymer framework. The triblock terpolymer was synthesized by sequential ring-opening polymerizations (ROPs) of two glucose-derived carbonate monomers, initiated by a PEG macroinitiator. Dopamine anchoring groups were subsequently installed by first introducing carboxylic acid groups using a thiol–yne click reaction, followed by amidation with dopamine. The resulting amphiphilic triblock terpolymers and MIONs were co-assembled to afford hybrid nanocomposites using solvent exchange processes from organic solvent to water. In combination with hydrophobic interactions, the linkage between dopamine and iron oxide stabilized the overall nanoscopic structure to allow for the establishment of a uniform globular morphology, whereas attempts at co-assembly with the triblock terpolymer precursor, lacking dopamine side chains, failed to afford well-defined nanostructures. The magnetic hybrid nanoparticles demonstrated high oil sorption capacities, ca. 8 times their initial dry weight, attributed, in part, to large surface areas leading to effective contact between the nanomaterials and hydrocarbon pollutants. Moreover, the naturally-derived polymer framework undergoes hydrolytic degradation to break down into byproducts that include glucose, ethanol and dopamine if not recovered after deployment, alleviating concerns of potential microplastic generation and persistence. 
    more » « less
  3. ; ; ; (, Applied Sciences)
    The widespread application of electrodialysis is constrained by the high cost of ion exchange membranes, necessitating the development of affordable alternatives. This study focuses on the fabrication and performance evaluation of cation exchange membranes made from polyethersulfone (PES) and sulfonated polyethersulfone (sPES). Membranes were synthesized through phase inversion with varying solvent evaporation times, using N-Methyl-2-Pyrrolidone (NMP) as the solvent. The structural and functional modifications were confirmed using FTIR, XPS, and AFM techniques. Performance tests identified optimal electrodialysis results for PES membranes with a 3 h solvent evaporation time and for sPES membranes with a 1 h evaporation time. Under varying operational conditions, including applied voltage, flow rates, and feed solutions, sPES membranes demonstrated superior performance, underscoring their potential for cost-effective brackish water desalination applications. 
    more » « less
  4. ; ; (, Macromolecular Chemistry and Physics)
    Abstract There is a considerable body of work that describes the scaling of diblock copolymer micelle dimensions in dilute and semi‐dilute solution based upon block degrees of polymerization and copolymer concentration. However, there is a lack of analogous information for semi‐dilute ABA triblock copolymer gels, which consist of ABA triblock copolymer dissolved in midblock‐selective (B‐selective) solvent. The present study uses small angle X‐ray scattering to extract micelle dimensions for numerous triblock copolymer gels that vary in copolymer identity (and hence block lengths) and copolymer concentration, as well as gels that contain various ratios of two unique triblock copolymers. Analysis of micelle structural data subsequently translates to universal scaling expressions for the micelle core radius –rA≈NA0.53NB−0.14ϕABA0.16whereNAandNBare the endblock and midblock degrees of polymerization, respectively, andϕABAis the volume fraction of triblock copolymer in the gel – and for the intermicelle spacing –lAA≈NA0.09NB0.29ϕABA−0.35. Each scaling expression describes the full collection of experimental data very well. Additionally, these scaling expressions are partially in line with expectations from semi‐dilute diblock copolymer solution theory. 
    more » « less
  5. ; ; ; ; (, Industrial & Engineering Chemistry Research)
    2-Methylpyrazine (2MP), a flavoring agent, was identified and used as a novel greener solvent for nonsolvent-induced phase separation (NIPS) fabrication of poly(ether sulfone) (PES) ultrafiltration (UF) membranes. Flat-sheet membranes were fabricated with 2MP-cosolvent blends, N,N-dimethylacetamide (DMAc), or dimethyl sulfoxide (DMSO), to investigate the influence of solvent choice on membrane properties and performance. The resulting membranes were characterized to assess morphology, productivity, and molecular weight cutoff (MWCO). In addition, kinetic and thermodynamic aspects of solvent choice on the polymer “dope” solutions during the NIPS process were examined. 2MP-cosolvent blends resulted in membranes with noticeably different morphologies, which arise from miscibility-hindered solvent–nonsolvent exchange during membrane formation. Membrane permeance was significantly lower for 2MP-cosolvent membranes when compared to DMAc and DMSO membranes; however, their MWCOs were clearly decreased. This initial study shows that 2MP is a promising greener solvent candidate for NIPS, and further investigations are warranted. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email