Homogeneous gelation leads to nanowire forests in the transition between electrospray and electrospinning

Lei, Lin; Chen, Shensheng; Nachtigal, Catherine; Moy, Tyler; Yong, Xin; Singer, Jonathan P.

doi:10.1039/d0mh00872a

Cited by 22 publications

(32 citation statements)

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“…DPD is a mesoscale coarse-grained method that is widely used in simulating polymers in solution − because of its computational efficiency and ability to capture hydrodynamics due to the explicit account of solvent. Coupled with electrostatic interaction, EDPD is a powerful tool to simulate polyelectrolyte solutions, − including PE complex coacervation systems. , In our simulations, we set all the DPD beads to have the same mass m and a cutoff interaction distance r c , which serve as the natural unit of mass and length, respectively . A DPD bead interacts with other beads through three types of short-ranged pairwise forces and the electrostatic force: .…”

Section: Simulation Methodsmentioning

confidence: 99%

Complexation between Oppositely Charged Polyelectrolytes in Dilute Solution: Effects of Charge Asymmetry

2022

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We use dissipative particle dynamics to study polyelectrolyte complexation in dilute solutions under conditions of either chain-length or concentration asymmetry between the polycation and the polyanion, characterized by the macromolecular charge ratio of the minor component to the major component. Our results show that generally the systems form clusters carrying net macromolecular charges. The stoichiometry of these net-charged macromolecular clusters depends on the overall charge asymmetry, and clusters with certain stoichiometry can dominate the cluster population under a wide range of chain-length and concentration asymmetry. The morphology and stability of these net-charged clusters are closely related to their stoichiometry. When the charge ratio reaches a threshold value, the polyions condense into a single large coacervate cluster, signaling the onset of macroscopic coacervation. The threshold value is less for concentration asymmetry systems than for chain-length asymmetry systems at the same salt concentration. This threshold value decreases with added salt, as salt ions cause merging of small clusters into larger ones, eventually leading to the dominance of a single large cluster. This “salting-out” phenomenon is followed by a “salting-in” behavior, as further addition of salt dissolves the large cluster. The preferred size and composition of the net-charged clusters observed in the simulation highlight the significant role of length and concentration asymmetry on polyelectrolyte complex coacervation and hint at the possibility of a microstructured liquid.

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Section: Simulation Methodsmentioning

confidence: 99%

Complexation between Oppositely Charged Polyelectrolytes in Dilute Solution: Effects of Charge Asymmetry

2022

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“…Here, the polyethylene glycol was added to lengthen wires as in our previous work. [ 18 ] These samples were fully covered and displayed nonwetting behavior when immersed in water as shown in Figure and Movie S1, Supporting Information, demonstrating the flexibility of the combined approach. As the droplets did not stick to the wire samples on immersion, no drying damage was observed.…”

Section: Discussionmentioning

confidence: 92%

“…In contrast, sprays completed at high concentrations and low flow rates result in especially short nanowires, large and small, respectively. [ 18 ] For ALD‐coated MC, there exists an interplay between the nanowire structures and wettability. According to the averaged WCA measurements (Figure 5a), as the flow rate increases from 0.02 to 0.05 mL h −1 , higher aspect ratio wires created at high flow rates result in more hydrophobic surfaces but also make these nanostructures more susceptible to collapse.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, our past results have found that glassy electrosprays, including MC sprays, can be performed in a conformal, self‐limiting electrospray deposition (SLED) mode that can be used to target complex surfaces both larger and smaller than the characteristic size of the spray. [ 18–21 ] SLED coatings asymptotically approach a self‐limited coating thickness, redirecting the spray to uncoated regions of the target, allowing for relatively uniform, conformal coatings of all exposed surfaces. In this study, to enhance the durability and water resistance of these nanowires, Al 2 O 3 thin films were deposited on the sprayed nanowires via atomic layer deposition (ALD), which has previously been applied to a wide variety of natural fibrous structures.…”

Section: Introductionmentioning

confidence: 99%

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Atomic Layer Deposition Reinforcement of Methylcellulose Nanowire Forests

Nachtigal

Zhang

et al. 2022

Adv Eng Mater

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“…18 Our own work classified how these self-limiting effects could be exploited to conformally coat complex 3D objects when certain conditions of the spray solution were met. [19][20][21] Specifically, the spray solution needs to arrive at the spray target as a non-conductive, glassy material. We refer to this regime as the self-limiting electrospray deposition (SLED).…”

Section: Introductionmentioning

confidence: 99%

Efficient electrospray deposition of surfaces smaller than the spray plume

Park

Liu

D'Souza

et al. 2022

Preprint

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Electrospray deposition (ESD) uses charged droplets at the micro- and nano-scale to create a wide variety of particles and coatings. In ESD, an electrostatic force is applied to a solution, which then disperses charged droplets loaded with the materials to be deposited on a grounded target. Because the droplets carry charge, repulsive effects due to accumulation of charge in a coating (self-limiting electrospray) or “crowding” of the spray droplets can reduce the efficiency of the approach. This is especially the case when the targets are smaller than the characteristic size of the spray plume. For this reason, while many studies have presumed high efficiency in ESD, the actual measured efficiencies for small targets are much lower. Here, it is shown how architecting the local “charge landscape” can lead to ESD coatings approaching 100% deposition efficiency on both flat and microneedle array targets composed of multiple model materials, including biocompatible polymers, proteins, and bioactive small molecules. In this way, ESD can be considered a viable alternative to other conformal approaches, such as dip or inkjet coating.

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Homogeneous gelation leads to nanowire forests in the transition between electrospray and electrospinning

Abstract: The morphology of coatings created by electrostatic deposition can be generally divided into three categories: wire mats, particles, and films. At intermediate regimes, there should exist nanowire forests as a...

Cited by 22 publications

References 50 publications

Complexation between Oppositely Charged Polyelectrolytes in Dilute Solution: Effects of Charge Asymmetry

Complexation between Oppositely Charged Polyelectrolytes in Dilute Solution: Effects of Charge Asymmetry

Atomic Layer Deposition Reinforcement of Methylcellulose Nanowire Forests

Efficient electrospray deposition of surfaces smaller than the spray plume

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