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Title: Luminescent tunable polydots: Charge effects in confined geometry

Abstract

Long-lived soft nanoparticles, formed by conjugated polymers, constitute a new class of far-from-equilibrium responsive structures for nano-medicine. Tethering ionizable groups to the polymers enables functionality. However concurrently, the ionic groups perturb the delicate balance of interactions that governs these particles. Using fully atomistic molecular dynamics simulations, this study probed the effects of charged groups tethered to poly para phenylene ethynylene substituted by alkyl groups on the polymer conformation and dynamics in confined geometry. As a result, we find that the ionizable groups affect the entire shape of the polydots and impact the conformation and dynamics of the polymer.

Authors:
 [1];  [1]; ORCiD logo [1]; ORCiD logo [2]
  1. Clemson Univ., Clemson, SC (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1372360
Report Number(s):
SAND-2017-4587J
Journal ID: ISSN 0021-9606; JCPSA6; 652929
Grant/Contract Number:
AC04-94AL85000; NA0003525
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 24; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Wijesinghe, Sidath, Maskey, Sabina, Perahia, Dvora, and Grest, Gary S. Luminescent tunable polydots: Charge effects in confined geometry. United States: N. p., 2017. Web. doi:10.1063/1.4990506.
Wijesinghe, Sidath, Maskey, Sabina, Perahia, Dvora, & Grest, Gary S. Luminescent tunable polydots: Charge effects in confined geometry. United States. doi:10.1063/1.4990506.
Wijesinghe, Sidath, Maskey, Sabina, Perahia, Dvora, and Grest, Gary S. 2017. "Luminescent tunable polydots: Charge effects in confined geometry". United States. doi:10.1063/1.4990506.
@article{osti_1372360,
title = {Luminescent tunable polydots: Charge effects in confined geometry},
author = {Wijesinghe, Sidath and Maskey, Sabina and Perahia, Dvora and Grest, Gary S.},
abstractNote = {Long-lived soft nanoparticles, formed by conjugated polymers, constitute a new class of far-from-equilibrium responsive structures for nano-medicine. Tethering ionizable groups to the polymers enables functionality. However concurrently, the ionic groups perturb the delicate balance of interactions that governs these particles. Using fully atomistic molecular dynamics simulations, this study probed the effects of charged groups tethered to poly para phenylene ethynylene substituted by alkyl groups on the polymer conformation and dynamics in confined geometry. As a result, we find that the ionizable groups affect the entire shape of the polydots and impact the conformation and dynamics of the polymer.},
doi = {10.1063/1.4990506},
journal = {Journal of Chemical Physics},
number = 24,
volume = 146,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 28, 2018
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  • The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less
  • The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. These new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less
  • Here, first-principles molecular dynamics simulations were used to investigate the dissociation of sarin (GB) on the calcium silicate hydrate (CSH) mineral tobermorite (TBM), a surrogate for cement. CSH minerals (including TBM) and amorphous materials of similar composition are the major components of Portland cement, the binding agent of concrete. Metadynamics simulations were used to investigate the effect of the TBM surface and confinement in a microscale pore on the mechanism and free energy of dissociation of GB. Our results indicate that both the adsorption site and the humidity of the local environment significantly affect the sarin dissociation energy. In particular,more » sarin dissociation in a low-water environment occurs via a dealkylation mechanism, which is consistent with previous experimental studies.« less
  • A velocity analyzer of adjustable interelectrode distance has been used to study the space-charge effects on the characteristic curve. The effects become apparent for distances larger than about 10{lambda}{sub {ital D}}. The theoretical analysis considering the trapped ions in the vicinity of the entrance grid leads to a better correlation with the experiments than that omitting them.