Influence of polymer structure on adsorption behavior at solid–liquid interface by Monte Carlo simulation

Conformational Transitions of Polymer Brushes for Reversibly Switching Graphene Transistors

“…As demonstrated in our previous publications, PEO–PS–PEO triblock copolymer chains with short PEO sticking blocks could form polymer brushes with a mixed population of loops and tails by end-anchoring the PS chains at the liquid/solid interface via either one or both PEO end-block(s) of a single polymer chain. ,,, For PEO–PS–PEO (128K, Table ) with relatively long PEO sticking blocks, the “tail” is the predominant conformation in the polymer brush formed in a good solvent (e.g., toluene), whereas PEO–PS–PEO (49K, Table ) forms more loop conformations under the same condition due to the longer PEO end blocks, and hence the stronger interactions with the substrate surface, than those in PEO–PS–PEO (128K). , Nevertheless, a tail-to-loop transition has been previously demonstrated for both the PEO–PS–PEO (49K) and PEO–PS–PEO (128K) chains upon the solvent change from toluene to cyclohexane. , In this study, the solvent-induced reversible tail-to-loop conformational transition (Figure a) was found to also lead to the reversible current switching (Figures b and c) similar to that of the diblock PS–PEO brush (Figure c). However, the PEO–PS–PEO (49K) showed faster (the chain transition kinetics is much faster than that experimentally measurable) and more pronounced conductance switching (Figure b) than that of the PEO–PS–PEO (128K) brush (Figure c) due to the stronger affinity to the substrate surface associated with the longer PEO segments in PEO–PS–PEO (49K) triblock copolymer chains …”

“…However, the PEO−PS−PEO (49K) showed faster (the chain transition kinetics is much faster than that experimentally measurable) and more pronounced conductance switching (Figure 5b) than that of the PEO−PS−PEO (128K) brush (Figure 5c) due to the stronger affinity to the substrate surface associated with the longer PEO segments in PEO−PS−PEO (49K) triblock copolymer chains. 46…”