Elaboration of Thermoresponsive Supramolecular Diblock Copolymers in Water from Complementary CBPQT⁴⁺ and TTF End‐Functionalized Polymers

Abstract

A well-defined poly(N-isopropyl acrylamide) 1 incorporating at one termini a cyclobis(paraquat-p-phenylene) (CBPQT(4+)) recognition unit is prepared via a RAFT polymerization followed by a copper-catalyzed azide-alkyne cycloaddition (CuAAC). (1)H NMR (1D, DOSY), UV-vis and ITC experiments reveal that polymer 1 is able of forming effective host-guest complexes with tetrathiafulvalene (TTF) end-functionalized polymers in water, thereby leading to the formation of non-covalently-linked double-hydrophilic block copolymers. The effect of the temperature on both the LCST phase transition of 1 and its complexes and on CBPQT(4+)/TTF host-guest interactions is investigated.

Polymer Nanospheres with Hydrophobic Surface Groups as Supramolecular Building Blocks Produced by Aqueous PISA

“…In both water and organic solvents, they spontaneously form a very stable pseudorotaxane host–guest complex (schematically shown in Figure ). Its dissociation can, however, be reversibly triggered by different external stimuli, such as heat, electrochemical oxidation/reduction, or the addition of competitive guest molecules …”

“…If both complementary units are linked to polymer chains, their spontaneous complexation leads to the formation of block copolymers with the supramolecular link in the middle of the chain . The redissociation to the individual polymer chains can be triggered by the aforementioned external stimuli and, in addition, the phase transition of one of the polymers which can in turn be actuated by temperature, solvent, pH value, or pressure …”

“…Its dissociation can, however, be reversibly triggered by different external stimuli, such as heat, electrochemical oxidation/reduction, [5] or the addition of competitive guest molecules. [2,6] When these units are covalently attached to polymer chains, their characteristic responsive capacities are imparted to the resulting material. [7,8] It was shown that the properties of polymers carrying dialkoxynaphthalene groups at the chain end are drastically, but reversibly, changed upon complexation of these units with the hydrophilic CBPQT 4+ · 4 Cl − .…”

“…[3] If both complementary units are linked to polymer chains, their spontaneous complexation leads to the formation of block copolymers with the supramolecular link in the middle of the chain. [9] The redissociation to the individual polymer chains can be triggered by the aforementioned external stimuli and, in addition, the phase transition of one of the polymers [6,10] which can in turn be actuated by temperature, solvent, pH value, or pressure. [11] Given the straightforwardness and flexibility of creating triggerable bonds, it is extremely promising to expand the toolbox of nanosized structures functionalized with these connector units beyond simple linear polymer chains to more advanced structures.…”

Catechol/boronic acid chemistry for the creation of block copolymers with a multi-stimuli responsive junction

“…radical, ionic), the first method is by far the most commonly used. Supramolecular chemistry was widely investigated to generate such "smart" block copolymers employing non-covalent junction 24 based on host-guest interactions or van der Waals force, [25][26][27][28][29][30] hydrogen bonding 31 and coordinative interactions. [17][18][19][20] In addition, providing stimuli responsiveness to polymers is also becoming a burgeoning area since such smart polymers are able to drastically change their intrinsic properties upon applying stimuli (i.e.…”