The review gathers together data concerning the influence of poly(2-substituted-2-oxazoline)s structure on their thermal and crystalline properties, and how this relationship can be adjusted in controlled manner.

Well-defined linear and multi-arm star polymer structures were used as the templates for in situ synthesis and stabilization of silver nanoparticles (AgNPs). This approach led to hybrid nanomaterials with high stability and antibacterial activity to both Gram-positive and Gram-negative bacterial strains. The ecologically friendly so called “green” synthesis of nanomaterials was performed through AgNPs preparation in the aqueous solutions of star and linear poly(N,N′-dimethylaminoethyl methacrylate)s (PDMAEMAs); the process was followed with time. The size, shape, and zeta potential of the obtained hybrids were determined. To our knowledge, this is the first time that the antibacterial activity of PDMAEMA hybrid nanomaterial against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa was investigated and assessed by minimum inhibitory concentration (MIC) and minimum biocidal concentration (MBC). Completely quaternized with ethyl bromide, star and linear PDMAEMAs were used in comparative biological tests. The modification of the polymers with in situ-formed AgNPs increased the antibacterial properties against all studied strains of bacteria by several times in comparison to non-modified polymers and quaternized polymers. These results yield novel nanohybrid materials that can be useful for applications in medicine and biology.

In this paper, we focus on the synthesis and characterization of novel stable nanolayers made of star methacrylate polymers. The effect of nanolayer modification on its antibacterial properties was also studied. A covalent immobilization of star poly(N,N′-dimethylaminoethyl methacrylate) (PDMAEMA) to benzophenone functionalized glass or silicon supports was carried out via a “grafting to” approach using UV irradiation. To date, star polymer UV immobilization has never been used for this purpose. The thickness of the resulting nanolayers increased from 30 to 120 nm with the molar mass of the immobilized stars. The successful bonding of star PDMAEMA to the supports was confirmed by surface sensitive quantitative spectroscopic methods. Next, amino groups in the polymer layer were quaternized with bromoethane, and the influence of this modification on the antibacterial properties of the obtained materials was analyzed using a selected reference strain of bacteria. The resulting star nanolayer surfaces exhibited higher antimicrobial activity against Bacillus subtilis ATCC 6633 compared to that of the linear PDMAEMA analogues grafted onto a support. These promising results and the knowledge about the influence of the topology and modification of PDMAEMA layers on their properties may help in searching for new materials for antimicrobial applications in medicine.

In this work, we sought to examine whether the presence of alkyl substituents randomly distributed within the main chain of a 2-isopropyl-2-oxazoline-based copolymer will decrease its ability to crystallize when compared to its homopolymer. At the same time, we aimed to ensure an appropriate hydrophilic/lipophilic balance in the copolymer and maintain the phase transition in the vicinity of the human body temperature. For this reason, copolymers of 2-ethyl-4-methyl-2-oxazoline and 2-isopropyl-2-oxazoline were synthesized. The thermoresponsive behavior of the copolymers in water, the influence of salt on the cloud point, the presence of hysteresis of the phase transition and the crystallization ability in a water solution under long-term heating conditions were studied by turbidimetry. The ability of the copolymers to crystallize in the solid state, and their thermal properties, were analyzed by differential scanning calorimetry and X-ray diffractometry. A cytotoxicity assay was used to estimate the viability of human fibroblasts in the presence of the obtained polymers. The results allowed us to demonstrate a nontoxic alternative to poly(2-isopropyl-2-oxazoline) (PiPrOx) with a physiological phase transition temperature (LCST) and a greatly reduced tendency to crystallize. The synthesis of 2-oxazoline polymers with such well-defined properties is important for future biomedical applications.