Multi-stimuli responsive supramolecular diblock copolymers

The influence of the macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agent architecture on the morphology of the self-assemblies obtained by aqueous RAFT dispersion polymerization in polymerization-induced self-assembly (PISA) is studied by comparing amphiphilic AB diblock, (AB) triblock, and triarm star-shaped (AB) copolymers, constituted of N,N-dimethylacrylamide (DMAc = A) and diacetone acrylamide (DAAm = B). Symmetrical triarm (AB) copolymers could be synthesized for the first time in a PISA process. Spheres and higher order morphologies, such as worms or vesicles, could be obtained for all types of architectures and the parameters that determine their formation have been studied. In particular, we found that the total DP of the PDMAc and the PDAAm segments, i.e., the same overall molar mass, at the same M (PDMAc)/M (PDAAm) ratio, rather than the individual length of the arms determined the morphologies for the linear (AB) and star shaped (AB) copolymers obtained by using the bi- and trifunctional macro-RAFT agents.

Section: Resultsmentioning

confidence: 99%

Beyond Simple AB Diblock Copolymers: Application of Bifunctional and Trifunctional RAFT Agents to PISA in Water

Mellot

Beaunier

Guigner

et al. 2018

“…The addition of PEtOx‐CBPQT 4+ to a solution of Naph or TTF containing polymers in water resulted in the appearance both of the typical purple and green colors of Naph and TTF based complexes, respectively, and their characteristic charge‐transfer absorption bands centered at 510 and 800 nm . The change in absorption intensity of these characteristic host–guest complex peak due to the gradual addition of PEtOx‐CBPQT 4+ solution to a solution of Naph or TTF containing polymers at 10 °C were monitored to measure their corresponding K a .…”

Section: Association Constants (Ka) and Diffusion Coefficient Of The mentioning

confidence: 99%

Supramolecular Competitive Host–Guest Interaction Induced Reversible Macromolecular Metamorphosis

Bera

Hou

Glaßner

et al. 2019

In this work, a rational strategy of competitive host–guest complexation between dioxynaphthalene (Naph) and tetrathiafulvalene (TTF) subunits as guests and cyclophane cyclobis(paraquat‐p‐phenylene) (CBPQT4+) module as host is exploited to modify the macromolecular architecture, so‐called supramolecular metamorphosis, in aqueous media. The architectures of the polymers can be reversibly transformed from a linear diblock copolymer AB to a linear AC block copolymer or from a linear block copolymer to a comb copolymer by redox switching. Interestingly, as TTF‐ and Naph‐based complexes feature different characteristic colors, it offers a great opportunity to directly observe nanoscaled macromolecular metamorphosis of materials with the naked eye.

“…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 − . 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 …”

Section: Emulsion Polymerizations Of Styrene In the Presence Of Macromentioning

confidence: 99%

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

Ebeling

Belal

Stoffelbach

et al. 2018

A robust and straightforward synthesis of waterborne polymer nanospheres bearing the supramolecular association unit dialkoxynapthalene at their surface is presented using polymerization-induced self-assembly (PISA). A RAFT agent bearing this unit is first employed to produce poly(acrylic acid) chains, which are then chain-extended with styrene (S) to spontaneously form the nano-objects via RAFT aqueous emulsion polymerization. The particular challenge posed by the dialkoxynapthalene hydrophobicity can be overcome by the use of PISA and the deprotonation of the poly(acrylic acid). At pH = 7, very homogeneous latexes are obtained. The particle diameters can be tuned from 36 to 105 nm (with a narrow particle size distribution) by varying the molar mass of the PS block. The surface accessibility of the dialkoxynapthalene moieties is demonstrated by complexation with the complementary host cyclobis(paraquat-p-phenylene) (CBPQT · Cl ), highlighting the potential of the nanospheres to act as building blocks for responsive supramolecular structures.