I. Rashkov

Fullerene core star-like polymers—1. Preparation from fullerenes and monoazidopolyethers

Abstract Monomethyl ethers of oligomeric polyoxyethylenes having azide end-groups were reacted with fullerenes (C60). Depending on the feed mole ratio, linear or star-like polymers were formed. The obtained fullerene-core star-like polymers (FCSP) were characterized by UV and FTIR spectroscopies, size-exclusion chromatography, vapor-pressure osmometry, thermogravimetric analysis, XPS measurements, and FAB-MS. The thermal stability of FCSP was higher than that of the starting polyethers. The thermal treatment of FCSP up to 1000°C did not lead to regeneration of C60. The FCSP gave stable emulsions of water-in-oil type in water/toluene system. FCSP showed herbicidal activity.

Preparation of PLLA/PEG nanofibers by electrospinning and potential applications

Poly(L-lactide) (PLLA)/polyethylene glycol (PEG) mixed solutions were successfully electrospun into micro-or nanofibrous polymer mats. The fiber diameter was in the range 100nm-6μm. The effect of the concentration of the spinning solutions and the ratio of PLLA/PEG on the fiber diameter and morphology was investigated. The hydrophilicity was tuned by varying the PLLA/PEG ratio. The tissue compatibility of the electrospun nanofibrous scaffolds was screened using two different cell models of human dermal fibroblasts and the osteoblast-like cell line MG-63. Both types of cells attached uniformly and approximately equally to all PLLA/PEG nanofibers. In long-term cultures osteoblast-like cells tend to spatially organize in tissue-like structure, particularly within the scaffold with the highest PEG content (PLLA/PEG at weight ratio 70/30). These results indicate that PLLA mixed with hydrophilic PEG produces a promising new biocompatible material for engineering scaffolds.

Synthesis and characterization of poly(oxyethylene)–poly(caprolactone) multiblock copolymers

Novel poly(oxyethylene)/poly(caprolactone) POE/PCL copolymers were synthesized by step growth polymerization of poly(e-caprolactone) diols and poly(ethylene glycol) diacids using dicyclohexylcarbodiimide as coupling agent. The reaction was performed at room temperature and yielded multiblock copolymers with predetermined POE and PCL block lengths. The resulting copolymers were characterized by various analytical techniques including SEC, IR, 1H NMR, DSC and X-ray diffractometry. Data showed that the properties of these polymers can be modulated by adjusting the chain lengths of the macromonomers. In particular, one or two crystalline structures can exist within the copolymers of various crystallinities.

Homopolymers of 5-chloro-8-quinolinyl acrylate and 5-chloro-8-quinolinyl methacrylate and their copolymers with acrylic and methacrylic acid

Abstract Optimal conditions for the preparation of 5-chloro-8-quinolinyl acrylate (AQ) and 5-chloro-8-quinolinyl methacrylate (MQ) were found. Homopolymers were obtained by radical polymerization of AQ and MQ. Copolymers were obtained by copolymerization of AQ with acrylic acid (AA) and MQ with methacrylic acid (MA). The obtained monomers and polymers were characterized by spectroscopic methods (i.r., 1 H and 13 C-NMR), gel-permeation chromatography (GPC) and differential scanning calorimetry (DSC). It was shown that the water-soluble copolymers of AA and AQ (AQ content 5 or 14 mol%) form interpolymer complexes with poly(N-vinyl-2-pyrrolidone).

5-Chloro-8-quinolinyl acrylate and n-vinyl-2-pyrrolidone copolymers: Synthesis, characterization and complexes with poly(methacrylic acid)

Abstract New copolymers of 5-chloro-8-quinolinyl acrylate (AQ) and N-vinyl-2-pyrrolidone (VP) were obtained by radical copolymerization in benzene or in DMF. Values of reactivity ratios for VP (M1) and AQ (M2) were r1 = 0.11 and r1 = 0.35 according to the Fineman-Ross method and 0.09 and 0.29 according to the Kelen-Tudos method, respectively. The product of the reactivity ratios, r1 × r1, was less than unity indicating a tendency towards alternation in the formation of copolymers. At considerable excess of VP and by the “compensation” method of polymerization, it was possible to obtain polymers, containing blocks of VP repeating units. It was shown that polymers with high VP content did not form interpolymer complexes in DMF with poly(methacrylic acid) and did not form interpolymer complexes with poly(acrylic acid). The polycomplexes were stable in the temperature range 20–80 °C. On increasing AQ content in the copolymers, the stability of the polycomplexes decreased and copolymers with AQ content higher than 30 mol% did not form interpolymer complexes.

Metal ion complex formation of poly(oxyethylene) with 5-chloro-8-quinolinoxyl end-groups

Abstract Complex formation between α-(5-chloro-8-quinolinoxy)-ω)-(5-chloro-8-quinolinyl)poly (oxyethylene) (POE ∗ ) and Fe 3+ ions as well as the formation of interpolymer complexes between POE ∗ and polyacrylic acid (PAA) in the presence of Fe 3+ were studied. The complexes were characterized by u.v.-vis spectroscopy. The stoichiometry and stability constants of the complexes were determined from changes in absorption due to complexation of the quinolinoxy groups of POE ∗ with Fe 3+ .

Preparation and metal ion complexing ability of polyethers with 8-hydroxy-5-quinolinyl end-groups

Abstract Polyethers with 8-hydroxy-5-quinolinyl end-groups (P–Q) were prepared by reaction of polyethers having amino end-groups with 5-chloromethyl-8-quinolinol hydrochloride. The modified polymers were characterized by SEC, UV, IR and 1H-NMR spectroscopy. The complexation between P–Q and Fe3+ or bivalent metal ions was studied. The stability of the complexes was estimated by UV/Vis spectroscopy and the following order was found: Cu2+>Ni2+>Zn2+>Cd2+≥Mn2+. The metal ion complexes of P–Q were water-soluble.

Antibacterial and antimycotic activity of a cross-linked electrospun poly(vinyl pyrrolidone)–iodine complex and a poly(ethylene oxide)/poly(vinyl pyrrolidone)–iodine complex

Photo-cross-linked poly(vinyl pyrrolidone) (PVP) and poly(ethylene oxide)(PEO)/PVP electrospun nanofibrous mats containing complex-bound iodine have been studied. FT-IR spectroscopy analyses have proved that coordination of molecular iodine with carbonyl group and nitrogen atom of pyrrolidone rings of the PVP chains has taken place. The distribution of iodine along the fibers is uniform as revealed by X-ray mapping. The microbiological tests have demonstrated that the iodine complex-containing electrospun mats are highly effective against the Gram-positive bacterium Staphylococcus aureus, the Gram-negative bacterium Escherichia coli and the fungus Candida albicans. Comparison with iodine complex-containing films has shown that the iodine complex-containing nanofibers exhibit a higher killing rate than the films against bacteria E. coli. SEM observations showed that PVP–iodine nanofibrous mats inhibit the adhesion of bacteria S. aureus. These characteristic features make the electrospun iodine-containing nanofibers good candidates for wound-dressing materials.

Poly(ϵ-caprolactone)s with 5-nitro and 5-chloro-8-quinolinoxyl end-groups

Abstract The synthesis of poly(ϵ-caprolactone)s with 5-nitro-8-quinolinoxyl and 5-chloro-8-quinolinoxyl end-groups is described. Two stage route is applied: modification of α,ω-dihydroxypoly(ϵ-caprolactone) with thionyl-chloride and reaction of α,ω-dichloropoly(ϵ-caprolactone) with potassium 5-nitro-8-quinolinolate or 5-chloro-8-quinolinolate, respectively. The obtained products have been characterized by GPC, 1 H-NMR and u.v.-vis spectroscopy. The covalent attachment of the quinolinoxyl groups to the polyester chain via ether bond has been shown. The alkaline hydrolysis of the modified products proceeds with random chain scission of the ester groups. The hydrolytic release of the corresponding quinolinolates is not observed. It has been proved that transesterification does not occur in the case of the reaction of potassium quinolinolate with the polyester chain.

Hydrolysis of chitosan, chitosan-polyoxyethylene and chitosan-poly(2-acryloylamido-2-methylpropanesulfonic acid) by a crude enzyme complex from Trichoderma viride

The degradation of chitosan using a crude enzyme complex from the soil fungus Trichoderma viride was examined in terms of temperature, pH, enzyme activity and the presence of a polymer partner. It was found that chitosan hydrolysis is not suppressed by combining it with polyoxyethylene or poly(2-acryloylamido-2-methylpropanesulfonic acid). The results on Trichoderma viride immobilized on beads imply that chitosan, as well as its polymer complexes are appropriate carriers for development of ecologically safe phytosanitary preparations.