4 years ago

Chain Exchange Kinetics of Asymmetric B1AB2 Linear Triblock and AB1B2 Branched Triblock Copolymers

Chain Exchange Kinetics of Asymmetric B1AB2 Linear Triblock and AB1B2 Branched Triblock Copolymers
Andrew J. Peters, Timothy P. Lodge
Equilibrium chain exchange of asymmetric B1AB2 and AB1B2 branched triblock copolymers in a B selective solvent has been studied via dissipative particle dynamics simulations. Hybridization simulations are performed using B1AB2 and AB1B2 branched triblock copolymers at varying levels of asymmetry and compared with equivalent AB diblock copolymers. It is found that B1AB2 triblocks exchange ∼1 order of magnitude faster than diblocks (persisting over various values of χNcore and total corona length), while AB1B2 triblocks exchange ∼4 times faster than diblocks. The dependence on asymmetry is weak, with very asymmetric triblocks (NB1NB2) exchanging only 2 or 3 times faster than symmetric triblocks. Two causes are found for this: (1) increases in the density of corona beads near the micelle core for triblocks, resulting in greater stretching penalties and lower aggregation numbers, and (2) looped core blocks (B1AB2) spending more time near the surface of a micelle core than unlooped core blocks (AB1B2 and AB), resulting in a lower energy benefit of insertion. Additionally, unlooped core blocks pull out bead-by-bead with multiple activations, whereas the looped core blocks tend to aggregate near the micelle surface and pull out as a single entity, potentially further reducing the energy penalty of pullout. Because of this difference in mechanism, the looped core triblocks pull out more rapidly than the unlooped core triblocks even at identical aggregation numbers.

Publisher URL: http://dx.doi.org/10.1021/acs.macromol.7b01046

DOI: 10.1021/acs.macromol.7b01046

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.