Simultaneously improving controls over molecular weight and stereoregularity of Poly(4-vinylpyridine) via a hydrogen bonding-facilitated controlled radical polymerization

NMR Studies of Block Copolymer-Based Supramolecules in Solution

Hierarchical assemblies from block copolymer (BCP)-based supramolecules have shown immense potential as programmable materials owing to their versatility for incorporating functional molecules and provide access to arrays of hierarchical structures. However, there remains a knowledge gap on the formation of the supramolecule in solution. Here, we applied NMR techniques to investigate the solution-phase behavior of the most studied supramolecular systems, polystyrene-block-poly(4-vinylpyridine)(3-pentadecylphenol) (PS-b-P4VP(PDP)_r). The results show that the supramolecule likely adopts a coil-comb conformation, despite the small molecule's (PDP) rapid exchange between the bonded and free states. The exchange rate (>10⁴ s^-1) exceeds the NMR time scale at the frequency of interest. The supramolecules form under dilute conditions (∼2 vol %) and are attributed to the enthalpic gain of the hydrogen bonding between the PDP and 4VP. As the solute concentration increases (>10 vol %), the supramolecule forms micelle-like aggregates with PDP accumulated within the comb-block's pervaded volume based on analysis of the apparent molecular weight, viscosity, and chain dynamics. This work sheds light on the long-standing question regarding the evolution of the constituents in the BCP-based supramolecule in solution and provides valuable guidance toward their solution-based processing and morphological control.

Probing Orientation-Specific Charge-Dipole Interactions between Hexafluoroisopropanol and Halides: A Joint Photoelectron Spectroscopy and Theoretical Study

The interactions between hexafluoroisopropanol (HFIP) and halogen anions X^- (F^-, Cl^-, Br^-, and I^-) have been investigated using negative ion photoelectron (NIPE) spectroscopy and ab initio calculations. The measured NIPE spectrum of each [HFIP·X]^- (X = Cl, Br, and I) complex shows a pattern identical to the corresponding X^- by shifting to the high electron binding energy side, indicative of the formation of the [HFIP···X^-] structure in which X^- interacts with HFIP via charge-dipole interactions. However, the spectrum of [HFIP·F]^- appears completely different from that of F^- and is more similar to the spectrum of the deprotonated HFIP anion (HFIP_-H^-). The geometry and electron density calculations indicate that a neutral HF molecule is formed upon HFIP interacting with F^- via proton transfer, rendering a stable structure of [HFIP_-H···HF]^-. Two conformers of [HFIP_-H·HF]^- with HFIP being in synperiplanar and antiperiplanar configurations, respectively, are observed, providing direct experimental evidences to show the distinctly different and orientation-specific interactions between HFIP and halide anions.

Toward alternating copolymerization of maleimide and vinyl acetate driven by hydrogen bonding

Herein, we report the solution copolymerization of N-propylmaleimide (MI) and vinyl acetate (VAc) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and 1,4-dioxane.

RAFT polymerization of N-vinylpyrrolidone mediated by cyanoprop-2-yl-1-dithionaphthalate in the presence of a fluoroalcohol: the possibility of altering monomer properties by hydrogen bonding?

This work illustrated the possibility of altering the monomer properties by using the hydrogen bonding interaction.

Hydrogen bonding promoting the controlled radical polymerization of 2-vinyl pyridine: supramonomer for better control

Hydrogen bonding can promote the controlled radical polymerization of 2-vinyl pyridine, and the monomer activating effect is elucidated for the first time.

Reversible deactivation radical polymerization in the presence of zero-valent metals: from components to precise polymerization

We highlight recent work from the advent of zero-valent metal-mediated RDRP looking at advances in its components and the synthesis of well-defined polymers.