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.


Title: Fluid Flow Templating of Polymeric Soft Matter with Diverse Morphologies
Abstract It is challenging to find a conventional nanofabrication technique that can consistently produce soft polymeric matter of high surface area and nanoscale morphology in a way that is scalable, versatile, and easily tunable. Here, the capabilities of a universal method for fabricating diverse nano‐ and micro‐scale morphologies based on polymer precipitation templated by the fluid streamlines in multiphasic flow are explored. It is shown that while the procedure is operationally simple, various combinations of its intertwined mechanisms can controllably and reproducibly lead to the formation of an extraordinary wide range of colloidal morphologies. By systematically investigating the process conditions, 12 distinct classes of polymer micro‐ and nano‐structures including particles, rods, ribbons, nanosheets, and soft dendritic colloids (dendricolloids) are identified. The outcomes are interpreted by delineating the physical processes into three stages: hydrodynamic shear, capillary and mechanical breakup, and polymer precipitation rate. The insights into the underlying fundamental mechanisms provide guidance toward developing a versatile and scalable nanofabrication platform. It is verified that the liquid shear‐based technique is versatile and works well with many chemically diverse polymers and biopolymers, showing potential as a universal tool for simple and scalable nanofabrication of many morphologically distinct soft matter classes.  more » « less
Award ID(s):
1825476 2029327 2134664
PAR ID:
10401170
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Materials
Volume:
35
Issue:
16
ISSN:
0935-9648
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, Biomaterials Science)
    null (Ed.)
    The development of synthetic methods for micro/nano materials with precisely controlled structures, morphologies, and local compositions is of great importance for the advancement of modern nanotechnology. The electrospray method is a “platform” approach for the preparation of a broad range of micro-/nanostructures; electrospray is simple and scalable. This review summarizes recent research on the micro-/nanostructures prepared via the electrospray route. These include spherical structures ( e.g. simple, porous, Janus, and core–shell particles), non-spherical structures ( e.g. red blood cell-like and spindle-like particles, multi-compartment microrods, 2D holey nanosheets, and nanopyramids), and assembled structures. The experimental details, underlying physical/chemical principles, and key benefits of these structures are comprehensively discussed. The effects and importance of nozzle design, properties of feeding solutions ( e.g. concentration of solute, polymer additives, solvent/nonsolvent combinations), working environment ( e.g. temperature and humidity), and types of collection media are highlighted. 
    more » « less
  2. ; ; ; ; ; ; ; ; (, ACS Applied Polymer Materials)
    With the growing number of applications for thin polymer films (e.g., corrosion-resistant coatings, photovoltaics, and optoelectronics), there is an urgent need to develop or advance cost-effective, versatile, and high-throughput manufacturing processes to produce thin polymer films and coatings with controllable properties (e.g., morphology, composition). In this work, we present a simple, cost-effective, and scalable approach: the air-assisted electrospray method for thin film coating. We systematically investigate its capabilities for producing coatings with a wide range of surface morphologies, its compatibility with three-dimensional substrates, and the fundamental understanding of the process. Through systematic control of concentration, needle configuration, and polymer selection, we demonstrate the ability to produce coating morphologies with diverse structural characteristics and excellent reproducibility. Notably, the introduction of air assistance through a coaxial needle greatly enlarges the range of achievable morphologies, particularly at lower concentrations. We also found that the position of the airflow relative to the solution is critical for determining the polymer film properties. Furthermore, we demonstrate its broad application potential in the fabrication of binderless electrodes for sodium-ion batteries. 
    more » « less
  3. ; (, Hilton Head Workshop 2024: A Solid-State Sensors, Actuators and Microsystems Workshop)
    Omniphobic surfaces, capable of repelling all types of liquids, are fundamentally reliant on the micro/nano doubly re-entrant structures, these overhanging structures, however, are prone to break under mechanical loading. Here, we report a robust technique to faithfully transfer an array of soft doubly re-entrant microstructures onto a target substrate, circumventing the limitation of demolding soft overhang structures, to realize a resilient omniphobic surface for the first time. The resulting surface not only exhibits omniphobic property, but also robust durability after substantial normal and shear mechanical stresses. The side view of the deformation and recovery of the structures against mechanical loads was captured under a microscope to help reveal the underlying mechanism. The innovative method presented in this study is scalable for the production of mechanically robust, omniphobic surfaces on a large scale. Such advancement facilitates the large-scale manufacturing of durable micro- and nanoscale surface textures, making them viable for practical applications. 
    more » « less
  4. ; ; (, Frontiers in Physics)
    Shear driven patterning is seen in many soft matter systems. We use rheology and optical microscopy to probe the structures formed when we shear a colloid-polymer mixture containing temperature-sensitive microgel particles. By increasing the temperature, we can increase the particle attraction and transition from liquid-like to gel-like behavior. And by applying shear flow to the sample as the temperature and, hence, state of the system changes, we can affect the morphology of mesoscopic colloidal clusters. We can produce gels comprised of fibrous, elongated colloid-dense clusters, or we can form more isotropic clusters. The rheology is measured and shear-induced flocculation observed for colloid-polymer systems with different cluster morphologies. At shear rates high enough to produce elongated clusters but low enough to not break clusters apart, we observe log-like flocs that are aligned with the vorticity direction and roll between the parallel plates of our rheometer. 
    more » « less
  5. ; ; (, American Composites Society)
    Micro-voids within the bead microstructure of additively manufactured short carbon fiber- reinforced polymer composites are known to compromise the material performance. Unfortunately, a comprehensive understanding of the formation mechanisms of micro-voids during polymer processing is currently lacking. The present study considers micro-void nucleation at fiber inter-faces, particularly those occurring at the end of suspended fibers. Micro-computed tomography (μCT) image acquisition techniques are used to characterize microstructural features of a 13wt% carbon fiber reinforced ABS compo-site bead manufactured via Large Area Additive Manufacturing (LAAM). The results reveal a significant collection of micro-voids at the tips of fibers approaching 80% of the total micro-void volume fraction. In addition, fiber tip micro-voids are relatively larger and less spherical than micro-voids isolated within the ABS matrix. Theoretical formulations of several known mechanisms for micro-void nucleation during LAAM material processing indicate that local-ized fluid pressure likely plays a pivotal role in micro-void formation. To better expose this mechanism, we simulate the hydrostatic flow-field pressure distri-bution surrounding a single rigid fiber suspended in simple shear flow using fi-nite element analysis (FEA). Computed results demonstrate that the polymer matrix pressure decreases significantly at the fiber ends where micro-void nucleation is experimentally observed to occur. Our approach provides the fiber surface pressure distribution in simple shear flow that typifies nozzle regions with extreme flow conditions, enhancing our understanding of micro-void development mechanisms as the polymer melt flows through the nozzle. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email