Nanostructuration by Self-Assembly in N-Alkyl Thiazolium and Triazolium Side-Chain Polymethacrylates

Lamellar Microphase Separation and Phase Transition of Hydrogen-Bonding/Crystalline Statistical Copolymers: Amide Functionalization at the Interface

Microphase separation of random copolymers, as well as that of high χ-low N block copolymers, is promising to construct sub-10-nm structures into materials. Herein, we designed statistical copolymers consisting of 2-hydroxyethyl acrylate (HEA) and N-octadecylacrylamide (ODAAm) to produce crystallization and hydrogen bond-assisted lamellar structure materials. The copolymers not only formed a crystalline lamellar structure with 3-4 nm domain spacing but also maintained an amorphous lamellar structure via phase transition above the melting temperature up to approximately 100 °C. The key is to introduce hydrogen-bonding amide junctions between the octadecyl groups and the polymer backbones, by which the polymer chains are physically fixed at the interface of lamellar structures even above the melting temperature. The stabilization of the lamellar structure by the amide units is also supported by the fact that the lamellar structure of all-acrylate random copolymers bearing hydroxyethyl and crystalline octadecyl groups is disordered above the melting temperature. By spin-coating on a silicon substrate, the HEA/ODAAm copolymer formed a multilayered lamellar thin film consisting of a hydrophilic hydroxyethyl/main chain phase and a hydrophobic octadecyl phase. The structure and order-disorder transition were analyzed by neutron reflectivity.

Dual-Cationic Poly(ionic liquid)s Carrying 1,2,4-Triazolium and Imidazolium Moieties: Synthesis and Formation of a Single-Component Porous Membrane

Both imidazolium and 1,2,4-triazolium cations are important functional moieties widely incorporated as building blocks in poly(ionic liquid)s (PILs). In a classical model, a PIL usually contains either imidazolium or 1,2,4-triazolium in its repeating unit. Herein, via exploiting the slight reactivity difference of alkyl bromide with imidazole and 1,2,4-triazole at room temperature, we synthesized dual-cationic PIL homopolymers carrying both imidazolium and 1,2,4-triazolium moieties in the same repeating unit, that is, an asymmetrically dicationic unit. We investigated their fundamental properties, for example, thermal stability and solubility, as well as their unique function in forming supramolecular porous membranes via a water-initiated phase-separation and cross-linking process. With such knowledge, we identified a water-based fabricate strategy toward air-stable porous membranes from single-component PILs. This study will enrich the design tools and chemical structure library of PILs and expand their application spectrum.

Influence of Polymer Composition and Substrate on the Performance of Bioinspired Coatings with Antibacterial Activity

A series of methacrylic copolymers bearing thiazolium cationic groups and catechol moieties were evaluated as antibacterial coatings on a variety of materials including aluminum and plastics such as polycarbonate, poly(methyl methacrylate), and silicone rubber. The thermal properties of the copolymers were first studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The cationic copolymers were thermally stable up to 200 °C and presented glass transition temperatures values well above 100 °C; thus, an acceptable thermal behavior for typical biomedical applications. The cationic copolymers with variable content of the adhesive anchoring N-(3,4-dihydroxyphenethyl) methacrylamide (DOMA) units were coated onto the metal and polymeric substrates by drop casting and the adhesive properties of the obtained coatings were further evaluated as a function of DOMA content and substrate. Optical profilometry, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra, and antimicrobial studies reveal that the coatings adhere stronger to metal substrates than to the polymeric substrates. The copolymers with higher content of DOMA, 24 mol.%, resist solvent erosion treatment when coated onto all substrates and exhibit antimicrobial activity against Gram-positive S. aureus bacteria after this erosion treatment. In contrast, copolymers with low content, 9 mol.% of DOMA, only remain attached onto the aluminum metal substrate after solvent treatment, while on polymeric substrates the coatings are almost removed and do not show any efficacy against S. aureus bacteria.

Engineering antimicrobial coating of archaeal poly-γ-glutamate-based materials using non-covalent crosslinkages

We are now entering a new age of intelligent material development using fine, sustainable polymers from extremophiles. Herein we present an innovative (but simple) means of transforming archaeal poly-γ-glutamate (PGA) into extremely durable polyionic complexes with potent antimicrobial performance. This new supra-polymer material (called PGA/DEQ) was subjected to nuclear magnetic resonance and X-ray diffraction spectroscopies to characterize in structural chemistry. Calorimetric measurements revealed its peculiar thermal properties; to the best of our knowledge, it is one of the most heat-resistant biopolymer-based polyionic complexes developed to date. PGA/DEQ is particularly useful in applications where surface functionalization is important, e.g., antimicrobial coatings. The spontaneously assembled PGA/DEQ coatings (without any additional treatments) were remarkably resistant to certain organic solvents (including chloroform), even at high salt concentrations (theoretically greater than those found in sea water), and various pH values. However, the pH-response tests also implied that the PGA/DEQ coatings could be removed only when concentrated citrate di-salts were used, whereas most crosslinked polymer composites (e.g., thermoset matrices) are difficult to recycle and treat downstream. We also discuss PGA/DEQ-immobilized surfaces that exhibit enigmatic microbicidal mechanisms.

1,2,3-Triazolium-Based Peptoid Oligomers

The cis-directing effect of the 1,2,3-triazolium-type side chain was studied on dimeric peptoid models with various patterns: αα, αβ, βα and ββ. Low influences of the sequence and of the solvent were observed, the cis conformation of the amide carrying the triazolium ranging from 83 to 94% in proportion. The synthesis of peptoid homooligomers with four or eight pendant 1,2,3-triazolium side chains is described. α-, β- and α,β-peptoids carrying propargyl groups were subjected to CuAAC reaction using alkyl azides, and the resulting triazoles were quaternized providing well-defined multitriazolium platforms. The influence of the counteranion (PF₆^-, BF₄^- or I^-) on the conformation was also studied.

“Leaching or not leaching”: an alternative approach to antimicrobial materials via copolymers containing crown ethers as active groups

New copolymers containing MMA and 18C6 crown-ether pendants, with or without a PEG arm, were synthesized to check if sequestering structural alkali-earth ions from the bacterial outer membrane (OM) may lead to bacterial death.

Phase behavior of side-chain liquid-crystalline polymers containing biphenyl mesogens with different spacer lengths synthesized via miniemulsion polymerization

High molar mass SCLCPs were synthesized by miniemulsion polymerization, and the phase behavior of the polymers was investigated by a combination of DSC, PLM, SAXS and WAXS.

Poly(1,2,3-triazolium)s: a new class of functional polymer electrolytes

Poly(1,2,3-triazolium)s are tunable and highly functional ion conducting materials that stretch out the actual boundaries of PILs macromolecular design.