Impact of Some Properties of Quaternized Polysulfone/Poly(Vinylidene Fluoride) Blend on the Potential Biomedical Applications

Blends of quaternized polysulfones with triphenylphosphonium pendant groups/poly(vinylidene fluoride) were analyzed to establish their impact on the rheological, morphological and surface properties, as well as their interactions with some blood compounds. The rheological functions reflect the influence of both polymers’ chemical structures. Blend compositions of the corresponding films influence the surface tension parameters, increase blend hydrophobicity and, implicitly, decrease the polar surface tension parameters. The specific surface characteristics of polymer blends are related to their interactions with some blood constituents and plasma proteins. Also, the specific microarchitecture of the blend represents an excellent scaffold for medical applications.     

Synthesis of hybrid nanocomposites based on new triazeno copolymers and montmorillonite used for detecting metal ions

The modern synthesis of novel functional materials with improved properties includes that of hybrid nanocomposites composed of inorganic nanoparticles and organic derivatives, where controlling the molecular structure at atomic and macroscopic dimensions is a key factor, with a major effect on performance. An extension of this approach to the field of nanocomposites containing photopolymers with triazene groups attached on a methacrylic backbone could be of great interest in the future development of chemosensors and photoresists, among others. Photopolymer/clay nanocomposites were prepared by in situ free radical copolymerization of 1‐(phenyl)‐3‐(2‐methacryloyloxyethylcarbamoyloxyethyl)‐3‐methyltriazene‐1 or 1‐(p‐methoxyphenyl)‐3‐(2‐methacryloyloxyethylcarbamoyloxyethyl)‐3‐methyltriazene‐1 and vinyl acetate or styrene in solution and in the presence of 3 and 5 wt% of organically modified montmorillonite. The characterization of the nanocomposites and pure copolymers was achieved through ¹H NMR and Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, X‐ray diffraction, atomic force microscopy and fluorescence analysis. The morphologies and properties of the nanocomposites are dependent on the nature of the triazene, on the co‐monomer structure and on the organoclay content. Also, the fluorescence response of these nanocomposites towards certain metal ions (Fe³⁺, Cu²⁺, Hg²⁺, Ni²⁺) in dimethylformamide solution was investigated. The effect of uranyl ions on the fluorescence intensity of the nanocomposites in solution or as films could be exploited in the development of ‘turn‐off’ or ‘turn‐on’ chemosensors for this type of analyte. Triazeno copolymer/organophilic montmorillonite nanocomposites with exfoliated (not completely exfoliated) or exfoliated and intercalated structures exhibit distinct characteristics concerning their fluorescence behaviour, a higher sensing ability towards certain target compounds (Fe³⁺, UO₂²⁺) being evidenced for those incorporating 3 wt% organoclay in solution and as films. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of polyurethane cationomer/MMT hybrid composite

BACKGROUND: The development of polymeric nanocomposites incorporating intercalated or exfoliated layered silicate clays into the organic matrix has been substantially motivated by the significant improvements induced by the presence of the inorganic component. Moreover, understanding and controlling the dispersion of inorganic layers into segmented polyurethane matrices by means of ionic interactions, and exploiting these interactions to enhance physicomechanical behaviour, could be of great interest in the field of polymer nanocomposites. RESULTS: New cationic polyurethane elastomers were prepared starting from poly(butylene adipate)diol (M_n = 1000 g mol^?1), 4,4′‐diphenylmethane diisocyanate, 1,4‐butanediol and N‐methyldiethanolamine or N,N′‐β‐hydroxyethylpiperazine, used as potential quaternizable moieties. The characterization of the polymers was achieved using specific analyses employed for the macromolecular samples (Fourier transform infrared and ¹H NMR spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography). An extension of our research on polymers reinforced with organically modified montmorillonite (OM‐MMT) in order to prepare hybrid composites with improved properties was performed and the resulting materials were characterized using TGA, X‐ray diffraction, atomic force microscopy and scanning electron microscopy. Also, the mechanical properties of the cationic polyurethane/OM‐MMT composites were investigated in comparison with the pristine ionic/non‐ionic polymers and their composites containing non‐ionic polymer blended with OM‐MMT or ionic polymer and unmodified MMT. CONCLUSION: The insertion of the organically modified clay into the polymeric matrix gave an improvement of the mechanical properties of the polyurethane composites, especially the tensile strength and stiffness of the hybrid materials. Copyright © 2009 Society of Chemical Industry     

Synthesis and characterization of some 2,4′-dibenzyldiisocyanate ionic polymers. V. Ionene polymers

Cationic polyurethanes containing piperazine rings on the macromolecular chain were synthesized by a Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide were used in the first step, and N,N′-dimethylpiperazine in the second step. The viscometric behaviour of dilute solutions in solvents with high dielectrical constants was studied.     

Synthesis and characterization of some 2,4′-dibenzyldiisocyanate ionic polymers

Cationic polyurethanes were synthesized by a two step Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide (1,3-dimethyl-4,6-di(chloromethyl) benzene) were used in the first step, and 1,8-diaza bicyclooctane in the second step. The polymers from flexible and transparent films and their solutions give ionomer dispersions by adding of acetone. The viscometric behaviour of diluted solutions was studied in solvents with different dielectrical constants.     

Ionomeric polyurethanes of pyridinium type with side azobenzene groups

New polyurethane cationomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with nitroazobenzene groups were studied. As a starting polymer, a polyurethane based on poly(tetramethylene oxide)diol, isophorone diisocyanate, and 2,6‐bis(hydroximethyl)pyridine was used. After a preliminary metalation of the above polymer with natrium hydride, by reaction of polyurethane N‐sodate with 4‐nitro‐4′(β–iodoethylurethane)azobenzene, chromophoric groups between 2.85 and 10.53 wt % could be incorporated instead of hydrogen. Such polymers partially functionalized with azobenzene and further quaternized with methyl iodide led to the formation of pyridinium polyurethane cationomers N‐modified with nitroazo groups. The photosensible properties of the azobenzene chromophore in a polymer solution and film state indicated important differences in their photoresponse. In the polymer solution, the trans–cis photoisomerization of the chromophore is accompanied by an irreversible photobleaching effect, while under the same UV irradiation conditions, the ionomeric films exhibited an enhanced photostability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1240–1247, 2002     

Synthesis and properties of photosensitive poly(urethane‐acrylate) containing anil groups with application in the chemosensors area

Some aspects of the enol‐imine to keto‐enamine photoisomerism and fluorescent behavior of the new monomer with urethane and anil units in its structure, namely, methacryloyloxyethyl‐2‐carbamoyloxy(m‐methyl, o‐hydroxybenziliden)aniline (UAN), were studied comparatively with the corresponding copolymer poly (methacryloyloxyethyl‐2‐carbamoyloxy(m‐methyl, o‐hydroxybenziliden)aniline)‐co‐methyl methacrylate) (COP‐UAN). The structure, thermal properties, and morphology of the anil compounds were investigated by Fourier transform infrared, proton nuclear magnetic resonance, fluorescence spectroscopies, UV spectrophotometry, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy. The photochromic behavior of salicylideneanil units was investigated by UV/laser irradiation, and an inspection of their photophysical properties suggested that such structures could function as fluorescent chemosensors for some transition metals, a fluorescence quenching in the presence of different metal cations (Fe³⁺, Fe²⁺, Cu²⁺, and Ni²⁺) being evidenced. The direct observation of an enhancement in the fluorescence emission caused of the presence of Zn²⁺ (solution) or Fe²⁺, Cu²⁺, and Zn²⁺ (thin film) would be rather suitable for the production of turn‐on fluorescent chemosensors. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Pyrene functionalized side chain alanine and histidine containing copolyacrylates prepared by free radical copolymerization

An optically active copolyacrylate, poly(N‐acryloyl‐L‐alanine‐co‐N‐acryloyl‐L‐histidine), is prepared by classical radical copolymerization of N‐acryloyl‐L‐alanine and N‐acryloyl‐L‐histidine, and further chemically modified with 1‐pyrene‐methanol. The structures of the synthesized compounds are confirmed by spectral analysis (FTIR, ¹H/¹³C‐NMR, UV, fluorescence spectroscopy), thermal methods, and molecular weight measurements. Also, their optical activity is studied using circular dichroism (CD) spectroscopy and optical rotation measurements. The specific rotation values reveal that the direction of rotation of the parent copolymer is dictated by the monomer containing L‐alanine. CD data suggest negative and positive Cotton effects regarding the monomers with amino acids. In the case of the unmodified copolymer it is noted the changes of ellipticity values with increasing pH while the random‐coil conformation is preserved, which makes it suitable as a pH‐responsive system. Photochemical and photophysical investigations reveal that the pyrene‐functionalized chiroptical copolyacrylate can be used as a fluorescent chemosensor for the detection of nitro‐derivatives in organic media. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44457.     

Synthesis of non-amphiphilic block copolymer with S-trityl-cysteine and pyrene units by ATRP polymerization: characterization and fluorescence study

A new diblock copolymer, 1-methylpyrene isobutyrate–poly(methyl methacrylate–block-N-acryloyl-S-trityl-cysteine)-Br (Py–PMMA–b-ATCys-Br), was synthesized by atom transfer radical polymerization (ATRP) of N-acryloyl-S-trityl-L-cysteine monomer (ATCys) with 1-methylpyrene isobutyrate–poly(methyl methacrylate)–Br as a macroinitiator. The diblock copolymer and its precursor were characterized by ¹H and ¹³C NMR spectroscopy, fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and glass transition temperatures (Tg) measurements. Fluorescence properties of the diblock copolymer were investigated using various quenching (Cu²⁺, Hg²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺ and Pb²⁺) in dimethylformamide solutions, the more efficient quenchers being the Cu²⁺, Hg²⁺, Fe²⁺, and Fe³⁺ ions. In addition, the effect of in situ photogenerated silver nanoparticles on the copolymer fluorescence was also investigated.     

New urethane oligodimethacrylates with quaternary alkylammonium for formulating dental composites

The aim of this study was to prepare urethane dimethacrylates containing quaternary alkyl (C16, C12) ammonium and polyethylene glycol short sequences (Mn, 400 g/mol) and to investigate their behaviour in some experimental formulations in order to evaluate their potential applicability in the dental composites field. The structure of urethane dimethacrylates has been confirmed by ¹H (¹³C) NMR and FTIR spectra, as well as by electrospray ionization tandem mass spectroscopy, and gel permeation chromatography measurements. The effects of the cationic macromers on the properties of the filled/non-filled composites were examined through FTIR, photoDSC, and specific measurements as volumetric polymerization shrinkage, water sorption/solubility, contact angle, mechanical parameters, and morphology. The monomer compositions based on cationic dimethacrylate (6.88–27.52 wt%), BisGMA-analogue (48.18–68.82 wt%) and TEGDMA (23.3 wt%) showed a good photoreactivity in terms of double bond conversion (DC, 50.07–68.81 %) and polymerization rate (R_p, 0.099–0.141 s^?1) measured by photoDSC compared to a control sample (BisGMA-1/TEGDMA: DC, 45.91 %; R_p, 0.162 s^?1), while the polymerization shrinkage increased in acceptable limits (5.37–7.74 vol%). The mechanical properties (compressive, flexural and diametral tensile strength) of the composite resin incorporating 70 wt% silanized zirconium silicate micro/nanopowder can be modulated by the initial co-monomer concentrations.