Noncovalently connected supramolecular metathesis graft copolymers: One-pot synthesis and self-assembly

Nanomicelles Array for Ultrahigh-Density Data Storage

High-density data storage devices based on organic and polymer materials are currently restricted by two key issues, size limitations and uniformity of memory cells. Herein, one triblock polymer is synthesized by ring-opening metathesis polymerization, where the polymer contains an electron-donor-acceptor (A₁ D) segment, an electron-acceptor (A₂ ) segment, and a hydrophilic segment, that shows ternary memory behavior in a conventional sandwich-type device. The polymers that have monodisperse molecular weight dispersity self-assemble into nanomicelles with a uniform size of 80 nm. Each nanomicelle is composed of an A₁ DA₂ -type hydrophobic core stabilized with a hydrophilic shell. Nanobowls based on conductive oxide are prepared via the template method, wherein the nanomicelles are present as independent nanoscale memory units to produce an array of micelle matrices. Investigations of the resulting nanomemory device using conductive atomic force microscopy show that the micelles exhibit a predominant semiconductor memory behavior. Compared to traditional ternary devices with a memory unit size of ≈1 mm, this innovative fabrication method based on arrayed uniform nanomicelles downscales the size of storage cells to 80 nm. Furthermore, the described system leads to a greatly enhanced storage density (>10⁸ times over the same area), which opens up new paths for further development of ultrahigh-density data storage devices.

Thermo/pH dual-responsive micelles based on the host-guest interaction between benzimidazole-terminated graft copolymer and β-cyclodextrin-functionalized star block copolymer for smart drug delivery

Novel temperature and pH dual-sensitive amphiphilic micelles were fabricated exploiting the host-guest interaction between benzimidazole-terminated PHEMA-g-(PCL-BM) and β-CD-star-PMAA-b-PNIPAM. The fabricated graft copolymer had a brush-like structure with star side chains. The micelles were utilized as dual-responsive nanocarriers and showed the LCST between 40 and 41 °C. The acidic pH promoted the dissociation of the PHEMA-g-(PCL-BM: β-CD-star-PMAA-b-PNIPAM) micelles. DOX.HCl was loaded into the core of the micelles during self-assembly in an aqueous solution with a high encapsulation efficacy (97.3%). The average size of the amphiphilic micelles was about 80 nm, suitable size for the enhanced permeability and retention effect in tumor vasculature. In an aqueous environment, these micelles exhibited very good self-assembly ability, low CMC value, rapid pH- and thermo-responsiveness, optimal drug loading capacity, and effective release of the drug. The biocompatibility was confirmed by the viability assessment of human breast cancer cell line (MCF-7) through methyl tetrazolium assay. DOX-loaded micelles displayed excellent anti-cancer activity performance in comparison with free DOX.

Poly(β-Cyclodextrin) Prepared by Ring-Opening Metathesis Polymerization Enables Creation of Supramolecular Polymeric Networks

The controlled synthesis of polymers containing densely grafted cyclodextrin units has proven challenging due to the steric hindrance of these cyclic oligosaccharides. In this study, we report the controlled synthesis of poly(β-cyclodextrin) [poly(β-CD)] through ring-opening metathesis polymerization (ROMP) using Grubbs third-generation catalyst. Molecular weights of >10⁵ g/mol were obtained with dispersity values (Đ) of ≤1.2. In aqueous solution, β-cyclodextrin forms a host-guest complex with adamantyl groups (Ad). These interactions were utilized to prepare supramolecular polymer networks (SPNs) made by adding poly(β-CD) to α,ω-adamantyl-functionalized poly(2-hydroxyethyl acrylate) (Ad-PHEA-Ad). These poly(β-CD)/Ad-PHEA-Ad SPNs were prepared in aqueous solution and then dried to make homogeneous, transparent films. Varying the ratios of the two components enabled structure-property studies via tensile measurements.