Antibacterial properties of poly ( N , N -dimethylaminoethyl methacrylate) obtained at different initiator concentrations in solution polymerization

The samples of poly( N , N -dimethylaminoethyl methacrylate) were synthesized by radical polymerization. The amount of monomer and solvent was constant as opposed to an amount of initiator which was changing. No clear relationship between polymerization conditions and the molecular weight of the polymer was found, probably due to the branched configuration of produced polymer. Bactericidal interactions in all samples against Gram-positive and Gram-negative bacteria have been demonstrated. However, the observed effect has various intensities, depending on the type of bacteria and the type of sample.

Bisphenol A Release from Dental Composites and Resin-Modified Glass Ionomers under Two Polymerization Conditions

Bisphenol A (BPA)-based monomers are commonly contained in dental resin-based materials. As BPA is an endocrine disruptor, its long-term release from restorative composites and resin-modified glass ionomers (RM-GICs) under two polymerization conditions was measured in this study. Specimens of two conventional composites containing BPA-based monomers, two “BPA-free” composites, and two RM-GICs were polymerized from one side for 20 s at 1300 mW/cm2 or for 5 s at 3000 mW/cm2. The amounts of BPA released in artificial saliva and methanol after 1, 4, 9, 16, 35, 65, 130, and 260 days were measured using liquid chromatography–tandem mass spectrometry. The highest amounts of BPA were released from conventional composites, followed by RM-GICs, while the least was released from “BPA-free” composites. Amounts of released BPA were significantly higher in methanol and decreased gradually after the first day. Fast polymerization (5 s at 3000 mW/cm2) resulted in a significantly higher release of BPA after 1 day, but the effect of polymerization conditions was not significant overall. In conclusion, fast polymerization increased the initial release of BPA, but the released amounts were significantly lower than the current tolerable daily intake (4 μg/kg body weight/day) even in methanol, representing the worst-case scenario of BPA release.

TiCl4/MgCl2/MCM-41 Bi-Supported Ziegler–Natta Catalyst: Effects of Catalyst Composition on Ethylene/1-Hexene Copolymerization

TiCl4/MgCl2/MCM-41 type bi-supported Ziegler-Natta catalysts with different MgCl2/MCM-41 ratios were synthesized by adsorbing TiCl4 onto MgCl2 crystallites anchored in mesopores of MCM-41 (mesoporous silica with 3.4 nm pore size). Ethylene/1-hexene copolymerization with the catalysts was conducted at different 1-hexene concentrations and ethylene pressures. MgCl2/MCM-41 composite supports and the catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption analysis (BET), and elemental analysis. The copolymers were fractionated by extraction with boiling n-heptane, and comonomer contents of the fractions were determined. Under 4 bar ethylene pressure, the bi-supported catalysts showed higher activity and a stronger comonomer activation effect than the TiCl4/MgCl2 catalyst. In comparison with the TiCl4/MgCl2 catalyst, the bi-supported catalysts produced much less copolymer fraction of low molecular weight and high 1-hexene content, meaning that the active center distribution of the catalyst was significantly changed by introducing MCM-41 in the support. The copolymer produced by the bi-supported catalysts showed similar melting temperature to that produced by TiCl4/MgCl2 under the same polymerization conditions. The space confinement effect of the mesopores of MCM-41 on the size and structure of MgCl2 crystallites is proposed as the main reason for the special active center distribution of the bi-supported catalysts.

Development and Characterization of Magnetic SARS-CoV-2 Peptide-Imprinted Polymers

The development of new methods for the rapid, sensitive, and selective detection of SARS-CoV-2 is a key factor in overcoming the global pandemic that we have been facing for over a year. In this work, we focused on the preparation of magnetic molecularly imprinted polymers (MMIPs) based on the self-polymerization of dopamine at the surface of magnetic nanoparticles (MNPs). Instead of using the whole SARS-CoV-2 virion as a template, a peptide of the viral spike protein, which is present at the viral surface, was innovatively used for the imprinting step. Thus, problems associated with the infectious nature of the virus along with its potential instability when used as a template and under the polymerization conditions were avoided. Dopamine was selected as a functional monomer following a rational computational screening approach that revealed not only a high binding energy of the dopamine–peptide complex but also multi-point interactions across the entire peptide template surface as opposed to other monomers with similar binding affinity. Moreover, variables affecting the imprinting efficiency including polymerization time and amount of peptide and dopamine were experimentally evaluated. Finally, the selectivity of the prepared MMIPs vs. other peptide sequences (i.e., from Zika virus) was evaluated, demonstrating that the developed MMIPs were only specific for the target SARS-CoV-2 peptide.

Physical, Chemical, and Electrochemical Properties of Redox-Responsive Polybenzopyrrole as Electrode Material for Faradaic Energy Storage

Polybenzopyrrole (Pbp) is an emerging candidate for electrochemical energy conversion and storage. There is a need to develop synthesis strategies for this class of polymers that can help improve its overall properties and make it as suitable for energy storage applications as other well-studied polymers in this substance class, such as polyaniline and polypyrrole. In this study, by synthesizing Pbp in surfactant-supported acidic medium, we were able to show that the physicochemical and electrochemical properties of Pbp-based electrodes are strongly influenced by the respective polymerization conditions. Through appropriate optimization of various reaction parameters, a significant enhancement of the thermal stability (up to 549.9 °C) and the electrochemical properties could be achieved. A maximum specific capacitance of 166.0 ± 2.0 F g−1 with an excellent cycle stability of 87% after 5000 cycles at a current density of 1 A g−1 was achieved. In addition, a particularly high-power density of 2.75 kW kg−1 was obtained for this polybenzopyrrole, having a gravimetric energy density of 17 Wh kg−1. The results show that polybenzopyrroles are suitable candidates to compete with other conducting polymers as electrode materials for next-generation Faradaic supercapacitors. In addition, the results of the current study can also be easily applied to other systems and used for adaptations or new syntheses of advanced hybrid/composite Pbp-based electrode materials.

Semi-Fluorinated Di and Triblock Copolymer Nano-Objects Prepared via RAFT Alcoholic Dispersion Polymerization (PISA)

A set of well-defined amphiphilic, semi-fluorinated di and triblock copolymers were synthesized via polymerization-induced self-assembly (PISA) under alcoholic dispersion polymerization conditions. This study investigates the influence of the length, nature and position of the solvophobic semi-fluorinated block. A poly(N,N-dimethylaminoethyl methacrylate) was used as the stabilizing block to prepare the di and tri block copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) controlled dispersion polymerization at 70 °C in ethanol. Benzylmethacrylate (BzMA) and semi-fluorinated methacrylates and acrylates with 7 (heptafluorobutyl methacrylate (HFBMA)), 13 (heneicosafluorododecyl methacrylate (HCFDDMA)) and 21 (tridecafluorooctyl acrylate (TDFOA)) fluorine atoms were used as monomers for the core-forming blocks. The RAFT polymerization of these semi-fluorinated monomers was monitored by SEC and 1H NMR. The evolution of the self-assembled morphologies was investigated by transmission electron microscopy (TEM). The results demonstrate that the order of the blocks and the number of fluorine atoms influence the microphase segregation of the core-forming blocks and the final morphology of the nano-objects.