High pressure RAFT of sterically hindered ionic monomers. Studying relationship between rigidity of the polymer backbone and conductivity

High pressure RAFT of sterically hindered ionic monomers. Studying relationship between rigidity... The synthesis of poly(ionic liquid)s (PILs), a new class of polymers with numerous possible applications and tailored thermorheological properties, is quite a challenging task. To achieve that goal, different strategies have been proposed and developed. However, in the majority of cases macromolecules with relatively low molecular weights and high dispersities were produced, probably due to the strong intermolecular coulombic interactions that determine the behavior of monomeric ionic liquids. In this paper, we proposed a completely new approach that relies on the pressure-induced reversible addition fragmentation chain transfer polymerization (RAFT) to produce PILs of desired properties. For this purpose, a series of model imidazolium-based ionic monomers, with different lengths of aliphatic side chains as additional steric hindrances, have been successfully polymerized under high pressure (p = 250, 500 and 800 MPa). In contrast to results obtained at ambient pressure, all monomers yielded high molecular weight polymers (degrees of polymerization DPn ≤ 10 000) with narrow dispersities (Ð∼1.10). From the kinetic data obtained at various thermodynamic conditions, the rate of polymerization, Rp, and overall activation volumes, ΔV, were estimated, which in the limit of low pressures varied as follows −16.7, −18.1, −32.6 and −35.6 cm mol−1 for [MVIM][NTf2], [EVIM][NTf2], [BVIM][NTf2] and [OVIM][NTf2], respectively. An unexpected significant jump in ΔV can be correlated with the nanostructure organization that, accordingly to the literature, starts to dominate in the latter two monomers. It was also demonstrated that below p = 500 MPa, the termination reaction is almost completely suppressed, independently on the sample. On the other hand, above that pressure both the polymerization rate and the control over the reaction decreased due to the high viscosity preventing diffusion of the monomers. Moreover, taking advantage of the high pressure polymerization, we had a unique opportunity of exploring and better understanding a correlation among molecular weight, Mn, the glass transition temperature, Tg, and the dc conductivity, σdc, for a very wide range of Mn (up to 430 kg/mol) polymers of various backbone rigidity. We observed that the evolution of Tg with Mn follows a typical Fox-Flory relation. Nevertheless, Tg decreases with an increase in the size of the monomer. Additionally, a similar chemical structure dependence was observed for the dc conductivity, which seems to strongly depend on the rigidity of the produced polymers. It can be seen that the higher rigidity of the polymer (longer alkyl chain of side group), the higher σdc. We believe the results reported herein offer an easy alternative way to synthesis of well-defined polyelectrolytes of moderate/high conductivity in shorter reaction times, and expand our knowledge of their properties and the correlations among them. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Polymer Elsevier

High pressure RAFT of sterically hindered ionic monomers. Studying relationship between rigidity of the polymer backbone and conductivity

Loading next page...
 
/lp/elsevier/high-pressure-raft-of-sterically-hindered-ionic-monomers-studying-JxCa8O8e0H
Publisher
Elsevier
Copyright
Copyright © 2018 Elsevier Ltd
ISSN
0032-3861
D.O.I.
10.1016/j.polymer.2018.02.030
Publisher site
See Article on Publisher Site

Abstract

The synthesis of poly(ionic liquid)s (PILs), a new class of polymers with numerous possible applications and tailored thermorheological properties, is quite a challenging task. To achieve that goal, different strategies have been proposed and developed. However, in the majority of cases macromolecules with relatively low molecular weights and high dispersities were produced, probably due to the strong intermolecular coulombic interactions that determine the behavior of monomeric ionic liquids. In this paper, we proposed a completely new approach that relies on the pressure-induced reversible addition fragmentation chain transfer polymerization (RAFT) to produce PILs of desired properties. For this purpose, a series of model imidazolium-based ionic monomers, with different lengths of aliphatic side chains as additional steric hindrances, have been successfully polymerized under high pressure (p = 250, 500 and 800 MPa). In contrast to results obtained at ambient pressure, all monomers yielded high molecular weight polymers (degrees of polymerization DPn ≤ 10 000) with narrow dispersities (Ð∼1.10). From the kinetic data obtained at various thermodynamic conditions, the rate of polymerization, Rp, and overall activation volumes, ΔV, were estimated, which in the limit of low pressures varied as follows −16.7, −18.1, −32.6 and −35.6 cm mol−1 for [MVIM][NTf2], [EVIM][NTf2], [BVIM][NTf2] and [OVIM][NTf2], respectively. An unexpected significant jump in ΔV can be correlated with the nanostructure organization that, accordingly to the literature, starts to dominate in the latter two monomers. It was also demonstrated that below p = 500 MPa, the termination reaction is almost completely suppressed, independently on the sample. On the other hand, above that pressure both the polymerization rate and the control over the reaction decreased due to the high viscosity preventing diffusion of the monomers. Moreover, taking advantage of the high pressure polymerization, we had a unique opportunity of exploring and better understanding a correlation among molecular weight, Mn, the glass transition temperature, Tg, and the dc conductivity, σdc, for a very wide range of Mn (up to 430 kg/mol) polymers of various backbone rigidity. We observed that the evolution of Tg with Mn follows a typical Fox-Flory relation. Nevertheless, Tg decreases with an increase in the size of the monomer. Additionally, a similar chemical structure dependence was observed for the dc conductivity, which seems to strongly depend on the rigidity of the produced polymers. It can be seen that the higher rigidity of the polymer (longer alkyl chain of side group), the higher σdc. We believe the results reported herein offer an easy alternative way to synthesis of well-defined polyelectrolytes of moderate/high conductivity in shorter reaction times, and expand our knowledge of their properties and the correlations among them.

Journal

PolymerElsevier

Published: Mar 28, 2018

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial