Supramolecular Four-Armed Star A₂B₂ Copolymer (Miktoarm Star) via Host–Guest Complexation and Nitroxide-Mediated Radical Polymerization

Abstract

A supramolecular four-armed star copolymer was prepared from the pseudorotaxane complex of a crown-centered polystyrene and a bis­(2,2,6,6-tetramethylpiperidinyl-1-oxy) viologen compound and n-butyl methacrylate (BMA) by nitroxide-mediated polymerization of the latter. Solvent fractionation with dioxane/THF/MeOH removed a small amount of a high molecular weight poly­(BMA) homopolymer. The molecular weight increase from its monomodal size exclusion chromatographic trace gives direct evidence of the four-armed star copolymer formation; there is no residual starting polystyrene. NMR spectroscopy shows the two components of the copolymer and confirms the presence of the central [2]­rotaxane unit. Differential scanning calorimetry displays two glass-transition temperatures, which correspond closely to those of polystyrene and poly­(BMA).

On-Site Supramolecular Adhesion to Wet and Soft Surfaces via Solvent Exchange

“…Different concentrations of ethanol solutions (25–50 wt %) were employed for solubility tests. High viscosity was observed for the concentrated poly­(TA) or poly­(TA-CA)­s ethanol solutions (Figure e), indicating the existence of polymeric structures in the solution state. ,,, Macroscopic experiments demonstrate the feasibility of the solvent-exchange-induced on-site adhesion: viscous, water insoluble, and amorphous adhesives were formed immediately after the addition of pure water into poly­(TA-CA)­s ethanol solution ( vice versa ) (Figure a, Figures S36–S38, and Video S1). Rheology measurements and dynamic thermomechanical analysis (DMA) of the as-synthesized adhesive materials displayed good viscoelasticity and mechanical strength (Figure f–h, Figures S29–S31, Figures S40–S43, and Video S2).…”

“…High viscosity was observed for the concentrated poly(TA) or poly(TA-CA)s ethanol solutions (Figure 2e), indicating the existence of polymeric structures in the solution state. 3,4,32,34 Macroscopic experiments demonstrate the feasibility of the solvent-exchange-induced on-site adhesion: viscous, water insoluble, and amorphous adhesives were formed immediately after the addition of pure water into poly(TA-CA)s ethanol solution (vice versa) (Figure 2a S39). These features indicate that poly(TA-CA)s can be used as adhesive materials to wet and soft surfaces via solvent exchange.…”

“…Over the past three decades, supramolecular polymers have been intensively investigated and have attracted continual attention in the field of supramolecular chemistry and material science. − Diverse supramolecular polymers typify a new generation of adaptive materials that have shifted from laboratories to real-life applications. − With the expansion of polymeric supramolecular systems, supramolecular polymers with practical applications are garnering increased attention. , …”

Crown Ether‐Based Supramolecular Polymers: From Synthesis to Self‐Assembly

“…[ 100 ] They designed and prepared a four‐arm star CSP through the host–guest interaction of BMP32C10/viologen. [ 101 ] As shown in Figure , the polymer 115 was crown ether‐center polystyrene, and the polymer 116 was bis(2,2,6,6‐tetramethylpiperidinyl‐1‐oxy) viologen initiator. A star CSP 117 can be formed through the host–guest interaction of 115 and 116 under the presence of the n‐butyl methacrylate.…”

“…Chemical structure of the 115 and 116 and graphical representation of the preparation of a star CSP 117 from the 115 and 116. Adapted with permission [101]. Copyright 2020, American Chemical Society.…”