Poly(vinylamine). Synthesis and characterization

Molecular dynamics simulations of structure and dynamics in aqueous solution of neutral and ionized derivatives of poly(F): methyl, n-propyl, and isopropyl substitutions

Chain dimensions, intermolecular structure and hydration of a series of uncharged and cationic poly(vinyl amine) [PVAm] linear polymers having hydrophobic substituent methyl, n-propyl, and isopropyl in the monomer are studied in aqueous solution by molecular dynamics simulations. A conformational transition occurs in the degree of ionization, α, range 0.3 to 0.4. Among the polymers studied, isopropyl substituted PVAm is most hydrophobic and methyl substituted PVAm is the least. The extent of hydrophobicity of the chemical structure is directly correlated to the size of the polymer chain. Conformational dynamics become slower with increase in the degree of charge of the chain and with the size of the substituent side group. The significant hydration of the polymers takes place for 0 ≤ α ≤ 0.5. While the number of H-bonds is not affected significantly by the chemical structure of the chain the relaxation dynamics of polymer-water H-bonds is significantly affected, with the more hydrophobic polymer showing the slowest dynamics. The steric hindrance provided by the hydrophobic substituent groups is responsible for slowing of water orientation dynamics in the vicinity of the polymer. The counter-ion condensation is clearly better and the bound water content is less for the relatively more hydrophobic polymer. The overall behavior of structure and dynamics is in qualitative agreement with that known for other types of polyelectrolytes and solutes in aqueous solution.

Bactericidal surfaces prepared by femtosecond laser patterning and layer-by-layer polyelectrolyte coating

Antimicrobial surfaces are important in medical, clinical, and industrial applications, where bacterial infection and biofouling may constitute a serious threat to human health. Conventional approaches against bacteria involve coating the surface with antibiotics, cytotoxic polymers, or metal particles. However, these types of functionalization have a limited lifetime and pose concerns in terms of leaching and degradation of the coating. Thus, there is a great interest in developing long-lasting and non-leaching bactericidal surfaces. To obtain a bactericidal surface, we combine micro and nanoscale patterning of borosilicate glass surfaces by ultrashort pulsed laser irradiation and a non-leaching layer-by-layer polyelectrolyte modification of the surface. The combination of surface structure and surface charge results in an enhanced bactericidal effect against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The laser patterning and the layer-by-layer modification are environmentally friendly processes that are applicable to a wide variety of materials, which makes this method uniquely suited for fundamental studies of bacteria-surface interactions and paves the way for its applications in a variety of fields, such as in hygiene products and medical devices.

Polyvinylamine: a tool for engineering interfaces

With the highest content of primary amine functional groups of any polymer, polyvinylamine (PVAm) is a potent tool for the modification of macroscopic and nanoparticle surfaces. Based on the free radical polymerization and subsequent hydrolysis of N-vinylformamide, PVAm is prepared as linear polymers (0.8 kDa to >1 MDa), microgels, macrogels, and copolymers. The amine groups serve as reaction sites for grafting PVAm to surfaces and for the preparation of derivatives. Coupling low-molecular-weight molecules and oligomers gives PVAm-X, where X includes hydrophobes, carbohydrate oligomers, proteins, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), phenylboronic acids, and fluorocarbons. This contribution highlights the use of PVAm and PVAm-X to modify solid surface properties. Where possible, the PVAm properties and applications as an interfacial agent are compared to those of linear polyethylenimine, polyallylamine, and chitosan.