Semicrystalline Polymer Binary-Phase Structure Templated Quasi-Block Graft Copolymers

Fluorine-Containing Triblock Copolymer Vesicles with Microphase-Separated Structure

Introduction of a fluorine-containing block into block copolymers is an effective method to tune block copolymer nanoassemblies with a microphase-separated structure. However, this microphase-separated structure is difficult to clearly observe due to its nanoscale size. In this work, fluorine-containing ABC triblock copolymer vesicles of poly(ethylene glycol)-block-polystyrene-block-poly(4-vinylbenzyl pentafluorophenyl ether) (PEG-b-PS-b-PVBFP) are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization under dispersed condition. Owing to the choice of a suitable degree of polymerization of the three blocks, the synthesized PEG₄₅-b-PS₁₉₇-b-PVBFP₂₃₃ vesicles have a relatively large size of around 216 nm and a thin vesicular membrane with a thickness of around 28 nm. Ascribed to the relatively large size of the vesicles and the thin vesicular membrane, it is concluded that the fluorine-containing PVBFP block forms 9 nm columnar microdomains shielded by the PS phase in the vesicular membrane.

Structure and Properties of PVDF/PA6 Blends Compatibilized by Ionic Liquid-Grafted PA6

Compatibilization of immiscible blends is critically important for developing high-performance polymer materials. In this work, an ionic liquid, 1-vinyl-3-butyl imidazole chloride, grafted polyamide 6 (PA6-g-IL(Cl)) with a quasi-block structure was used as a compatibilizer for an immiscible poly(vinylidene fluoride) (PVDF)/PA6 blend. The effects of two PA6-g-IL(Cl)s (E-2%-50K and E-8%-50K) on the morphology, crystallization behavior, mechanical properties, and surface resistance of the PVDF/PA6 blend were investigated systematically. It was found that the two types of PA6-g-IL(Cl)s had a favorable compatibilization effect on the PVDF/PA6 blend. Specifically, the morphology of the PVDF/PA6 = 60/40 blend transformed from a typical sea-island into a bicontinuous structure after incorporating E-8%-50K with a high degree of grafting (DG). In addition, the tensile strength of the PVDF/PA6/E-8%-50K blend reached 66 MPa, which is higher than that of PVDF, PA6 and the PVDF/PA6 blend. Moreover, the PVDF/PA6/E-8%-50K blend exhibited surface conductivity due to the conductive path offered by the bicontinuous structure and conductive ions offered by grafted IL(Cl). Differential scanning calorimetry (DSC) and wide-angle X-ray diffractometry (WAXD) results revealed that PA6-g-IL(Cl) exhibits different effects on the crystallization behavior of PVDF and PA6. The compatibilization mechanism was concluded to be based on the fact that the nongrafted PA6 blocks entangled with the PA6 chains, while the ionic liquid-grafted PA6 blocks interacted with the PVDF chains. This work offers a new strategy for the compatibilization of immiscible polymer blends.

Ionic Liquids Grafted Cellulose Nanocrystals for High-Strength and Toughness PVA Nanocomposite

The surface functionalization of cellulose nanocrystals (CNCs) is of significant importance for promoting its diverse applications. However, the efficient strategy reported so far for cation functionalization of CNCs remains limited owing to the electrostatic attraction between cationic modifiers and electronegative CNCs. Herein, a cationized CNC (CNC-LA-IL) has been successfully prepared in aqueous media by grafting the [VBIm][BF₄], a kind of ionic liquid (IL), on the surface of a sulfated CNC using lactic acid (LA) as a linker molecule. This surface functionalization not only converts the negative charge of CNC suspensions to a positive charge (zeta potential reversed from -35 to +40 mV) but also leads to enhanced thermal stability and redispersibility of the dried CNC. To examine the reinforcing effect of IL-modified CNCs, poly(vinyl alcohol) (PVA)/CNC-LA-IL nanocomposite films were further prepared by the solution casting method. To one's surprise, the as-prepared PVA/CNC-LA-IL films exhibit extraordinary improvement in both the tensile strength (92%) and the toughness (166%) with only a 0.3 wt % CNC loading. This study provides a green and facile method to achieve ionic liquids grafted CNCs for high-performance nanocomposites.

Durable Anti-Superbug Polymers: Covalent Bonding of Ionic Liquid onto the Polymer Chains

Here, we fabricated the ionic liquid (IL) grafted poly(vinylidene fluoride) (PVDF) (PVDF-g-IL) via electron-beam irradiation to fight common bacteria and multidrug-resistant "superbugs". Two types of ILs, 1-vinyl-3-butylimmidazolium chloride (IL (Cl)) and 1-vinyl-3-ethylimidazolium tetrafluoroborate (IL (BF₄)), were used. It was found that the PVDF-g-IL exhibited superior antibacterial performance, with almost the same mechanical and thermal performance as unmodified PVDF. Nonwovens and films made from PVDF-g-IL materials exhibited broad-spectrum antimicrobial activity against common bacteria and "superbugs" with the strong electrostatic interactions between ILs and microbial cell membranes. With extremely low IL loading (0.05 wt %), the cell reduction of PVDF-g-IL (Cl) nonwovens improved from 0.2 to 4.4 against S. aureus. Moreover, the antibacterial activity of PVDF-g-IL nonwovens was permanent for the covalent bonds between ILs and polymer chains. The work provides a simple strategy to immobilize ionic antibacterial agents onto polymer substrates, which may have great potential applications in healthcare and household applications.