Coassembly of Block Copolymer and Randomly Methylated β-Cyclodextrin: From Swollen Micelles to Mesoporous Alumina with Tunable Pore Size

Abstract

Controlling interactions at the supramolecular level is of importance for the preparation by template directed synthesis of mesoporous materials with tailored pore structures. Herein we investigate the effect of randomly methylated β-cyclodextrin on the association behavior of the amphiphilic triblock copolymer Pluronic P123 in aqueous solution. Surface tension, dynamic light scattering, and viscosity measurements provide quantitative evidence that, when the cyclodextrin is added in controlled amounts to the copolymer, it strongly impacts the micellar growth rate. The property of randomly methylated β-cyclodextrin to act as a micelle expander has been further exploited to generate a series of mesoporous γ-alumina by a sol–gel method. The resulting materials subjected to calcination at 500 °C exhibit high surface area (354–382 m2/g), tunable pore size (14.8–19.3 nm), and very large pore volume (1.37–1.97 cm3/g), making them excellent candidates for applications in the fields of adsorption and heterogeneous catalysis.

Small molecule self‐assembly in polymer matrices

“…Upon increasing the concentration of RAMEB to 80 and 100 mg/mL, the R H increased to 15.5 and 31 nm, respectively, indicating the swelling of the micelles by the cyclodextrin. This was interpreted by Bleta et al as due to the hydrophobic affinity between the OCH 3 groups of RAMEB and the PPO block of the copolymer, leading to the assembly of the cyclodextrins in the interfacial layer, as shown in Figure (a). The location of the cyclodextrins in the interfacial layer also contributes to the change in the micellar curvature from spherical to ellipsoidal shape.…”

“…A similar template method was used by Bleta et al for synthesizing mesoporous alumina with controlled pore size, by taking advantage of the micellar co‐assembly of a triblock copolymer and methylated cyclodextrin. Valero et al concluded that methylated β‐cyclodextrins do not form pseudorotaxanes with PEO–PPO–PEO.…”

“…Valero et al concluded that methylated β‐cyclodextrins do not form pseudorotaxanes with PEO–PPO–PEO. However, Bleta et al found that the copolymer PEO 20 PPO 70 PEO 20 (Pluronic P123, M w = 5800 g/mol) and a randomly methylated β‐cyclodextrin (denoted by RAMEB) co‐assembled in aqueous solutions. When varying amounts of RAMEB, up to 130 mg/mL, were added to the aqueous solution (7.8 wt%) of P123, the solutions remained transparent up to a concentration of 80 mg/mL, beyond which these became turbid suggesting the formation of large scattering objects.…”

Pseudo-Polyrotaxanes of Cyclodextrins with Direct and Reverse X-Shaped Block Copolymers: A Kinetic and Structural Study

“…[27][28][29][30][31] The interaction between native CDs and Pluronics leading to the formation of PRs and PPRs has been described in the literature. 32,33 The substitution of the hydroxyl groups on the rims of the CD strongly modifies the aggregation behavior of the Pluronic micelles, depending on the specific nature of the substituents, [34][35][36] and the kinetics and mechanisms of the formation of the PPRs have been studied. [37][38][39] Specifically, the PRs formed with 2-hydroxypropyl β-CD and Pluronic have shown promise in the biomedical field for the treatment of Niemann-Pick disease.…”

Alumina Particles Are Snowballing with Propylene Oxide–Synthesis of Alumina Aerogels with Free Adjustable Particle and Pore Sizes

“…And that is precisely the focus of the current research. [4] While until now, although many studies have been involved in the regulation of the particle and channel sizes, such as by changing the structure template agent, [2,5,7] adjusting the solvents [8] and nanocasting from carbon aerogels [9] etc., the report clearly accessed to continuously adjustable particle and pore sizes is still very little. Here we put forward a simple method to synthesis of alumina aerogels with free adjustable particle and pore sizes.…”