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pH‐Responsive Side Chains as a Tool to Control Aqueous Self‐Assembly Mechanisms
Author(s) -
Kartha Kalathil K.,
Wendler Felix,
Rudolph Tobias,
Biehl Philip,
Fernández Gustavo,
Schacher F. H.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904284
Subject(s) - protonation , deprotonation , side chain , isodesmic reaction , chemistry , self assembly , aqueous solution , intermolecular force , hydrophobic effect , imine , polymer , polymer chemistry , organic chemistry , molecule , catalysis , ion
pH‐Tunable nanoscale morphology and self‐assembly mechanism of a series of oligo( p ‐phenyleneethynylene) (OPE)‐based bolaamphiphiles featuring poly(ethylene imine) (PEI) side chains of different length and degree of hydrolysis are described. Protonation and deprotonation of the PEI chains by changing the pH alters the hydrophilic/hydrophobic balance of the systems and, in turn, the strength of intermolecular interactions between the hydrophobic OPE moieties. Low pH values (3) lead to weak interaction between the OPEs and result in spherical nanoparticles, in which aggregation follows an isodesmic mechanism. In contrast, higher pH values (11) induce deprotonation of the polymer chains and lead to a stronger, cooperative aggregation into anisotropic nanostructures. Our results demonstrate that pH‐responsive chains can be exploited as a tool to tune self‐assembly mechanisms, which opens exciting possibilities to develop new stimuli‐responsive materials.