We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

Frontiers in poly(ionic liquid)s: syntheses and applications

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ev...

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(15)00188-2.pdf

Antibacterial Coatings: Challenges, Perspectives, and Opportunities

Bacterial infection is one of the top ten leading causes of death globally and the worst killer in low-income countries. The overuse of antibiotics leads to ever-increasing antibiotic resistance, posing a severe threat to human health. Recent advances in nanotechnology provide new opportunities to address the challenges in bacterial infection by killing germs without using antibiotics. Antibiotic-free antibacterial strategies enabled by advanced nanomaterials are presented. Nanomaterials are classified on the basis of their mode of action: nanomaterials with intrinsic or light-mediated bactericidal properties and others that serve as vehicles for the delivery of natural antibacterial compounds. Specific attention is given to antibacterial mechanisms and the structure-performance relationship. Practical antibacterial applications employing these antibiotic-free strategies are also introduced. Current challenges in this field and future perspectives are presented to stimulate new technologies and their translation to fight against bacterial infection.

https://espace.library.uq.edu.au/view/UQ:83fdbcc/UQ83fdbcc_OA.pdf

Antibiotic-Free Antibacterial Strategies Enabled by Nanomaterials: Progress and Perspectives.

Dual-function antibacterial surfaces for biomedical applications.

Polymer multilayers with pH-triggered release of antibacterial agents.

Self-defensive antibacterial layer-by-layer hydrogel coatings with pH-triggered hydrophobicity

We report on weak polyacid brushes with highly tunable pH and temperature response characteristics. This was achieved by synthesizing a series of homo- and copolymers which contain 2-alkylacrylic acids (aAAs) of increased hydrophobicity, i.e. acrylic acid (AA), methacrylic acid (MAA), or 2-ethylacrylic acid (EAA), using surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization. As revealed by contact angle measurements, in situ ellipsometry and AFM studies of brush swelling, the pH-response of PAA and PMAA brushes was similar, with brushes remaining highly swollen (swelling ratio 2.5–3.0) at low pH values. The PEAA brush, however, was unique as it showed low degrees of water uptake ( 70°) contact angles in the entire pH region from 2 to 8. Copolymer brushes of aAAs with N-isopropylacrylamide (NIPAM), denoted as P(AA-co-NIPAM), P(MAA-co-NIPAM) and P(EAA-co-NIPAM), demonstrated dual pH and temperature response, which was strongly dependent on the type of aAA co-monomer. P(AA-co-NIPAM) and P(MAA-co-NIPAM) brushes underwent large-amplitude pH-induced changes in brush swelling and water contact angle in the range of pH from 3 to 6, and were only weakly responsive to temperature in the transition region. In contrast, more hydrophobic P(EAA-co-NIPAM) brushes demonstrated both pH and temperature responses at physiologically relevant neutral/basic pH values even when the content of EAA units in the copolymer was as high as ∼50%. We discuss the role of inter- and intra-molecular hydrogen bonding and monomer hydrophobicity and ionization (quantified by FTIR) in determining pH ranges for brush response. These findings might enable control of molecular/cellular adhesion and flow at interfaces potentially useful in microfluidic and biomedical applications.

Tunable pH and temperature response of weak polyelectrolyte brushes: role of hydrogen bonding and monomer hydrophobicity

We report on the use of layer-by-layer (LbL) hydrogels, composed of amphiphilic polymers that undergo reversible collapse-dissolution transition in solutions as a function of pH, to induce sharp, large-amplitude wetting transition at microstructured surfaces. Surface hydrogels were composed of poly(2-alkylacrylic acids) (PaAAs) of varied hydrophobicity, i.e., poly(methacrylic acid) (PMAA), poly(2-ethylacrylic acid) (PEAA), poly(2-n-propylacrylic acid) (PPAA) and poly(2-n-butylacrylic acid) (PBAA). When deposited at a micropillar-patterned silicon substrate, hydrophilic PMAA LbL hydrogels supported complete surface wetting (contact angle, CA, of 0°), whereas PEAA, PPAA, and PBAA ultrathin coatings supported large-amplitude wetting transitions, with CA changes from 110 to 125° at acidic to 0° at basic pH values, and the transition pH increasing from 6.2 to 8.4 with increased polyacid hydrophobicity. At acidic pHs, droplets showed a large hysteresis in CA (a “sticky droplet” behavior), and remained in the We...

Large-amplitude, reversible, pH-triggered wetting transitions enabled by layer-by-layer films.

Recently, the Cu-based catalyst has attracted wide attention for the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG) due to its high catalytic activity and it is low cost. However, its poor stability, ease of agglomeration, and the short life of the catalyst restrict its further development in industrial applications. Here, we constructed a novel MOF-derived Cu/SiO2 catalyst (MOF-CmS for short) with a controllable distribution of Cu active sites for the hydrogenation of the DMO to EG reaction. The catalyst was prepared by a hydrothermal method with the HKUST-1 uniformly coated on the surface of the silica microspheres. After the calcination, the highly dispersed and uniform Cu species were loaded on the surface of the silica. The resulted MOF-CmS catalyst showed a 100% conversion of DMO and over 98% selectivity of EG at 200 °C and 2 MPa while a traditional Cu/SiO2 catalyst exhibited serious agglomeration of Cu active sites and low catalytic activity (DMO conversion of 86.9% and EG selectivity of 46.6%). It is believed that the highly dispersed active metal center and the interaction between the active metal and carrier were the main reasons for higher catalytic activity of the MOF-CmS catalyst. Therefore, the developed method opened another avenue to synthesize highly dispersed and stable Cu-based catalysts.

https://www.mdpi.com/2073-4344/12/11/1326/pdf?version=1666954243

Yiming Lu

Papers

Polymer multilayers with pH-triggered release of antibacterial agents.

Self-defensive antibacterial layer-by-layer hydrogel coatings with pH-triggered hydrophobicity

Tunable pH and temperature response of weak polyelectrolyte brushes: role of hydrogen bonding and monomer hydrophobicity

Large-amplitude, reversible, pH-triggered wetting transitions enabled by layer-by-layer films.

Anchoring Cu Species over SiO2 for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol