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Magnetic responsive hydrogels (CMX-cl-P4VP/M-NPs) were successfully synthesized through in situ co-precipitation procedure and investigated using various techniques. The surface morphology analysis revealed that the M-NPs were uniformly distributed within the hydrogel matrix and had average sizes ranging from 4.98 to 15.02 nm. The graft copolymer containing nanoparticles exhibited a sensitive magnetic response, and their recovery could be facilitated by applying a magnetic field. The purpose of this research is to study the ability of the prepared magnetic hydrogel to remove AO-10 dye and hexavalent chromium ions (Cr(VI)) from the aqueous solution under various factors, namely contact time, pH, amount of adsorbent, coexisting ions and AO-10 and Cr(VI) concentrations. The outcomes of the batch adsorption demonstrated that the adsorbent hydrogel incorporated with a low percentage (10 %) of M-NPs had a strong affinity for the removal of AO-10 dye and Cr(VI) ions at an optimum pH = 3, and the removal percentage reached 99.3 and 97.4 % for 500 mg L

Four series of di-flouro, namely; 4-substituted phenylazo-3-flouro phenyl-4′-n-alkoxy 3-flouro phenylazo benzoates (Ina-d) based on aromatic rings with the azo/ester/azo linkages core, were prepared and investigated for their mesomorphic properties. An alkoxy group with chain length varied from n = 6 to 16 is attached to the terminal phenylazobenzoate moiety and the other terminal is a compact group (X = –CH3O, –CH3, H and Br) attached to phenylazo moiety. The mesophases were investigated by DSC and POM and compared with previously investigated dilaterally methyl substituted analogues. Terminally unsubstituted and Br substituted analogues displayed dimorphic N and SmA phases, except the lower homologue (n = 6), while terminally – CH3O analogues exhibited monomorphic N phase. For terminally – CH3 substituted, compounds with n = 6–12 exhibited only N phase, while compounds with n = 14 and 16 displayed N and SmA phases. Meanwhile, the dilateral F substituents result in an enhancement in clearing thermal transitions compared with dilateral methyl substituents with a wide mesophase range. TGA analysis revealed that the prepared compounds are thermally stable within mesophase temperature range, except – CH3O, –CH3 and Br derivatives with n = 6. Binary mixtures of I6a-d/I16a-d derivatives were investigated. The photo-physical property was also studied.

Radiation-induced Ag° nanoparticles (NPs) in silver nitrate gel dosimeter incorporating various components was investigated in the dose range of 0–100 Gy. The gel responses were analyzed at 450 nm, a Surface Plasmon Resonance band of AgNPs. The radiation sensitivity of the gel increases with increasing Ag+ concentrations and isopropanol, % and decreases with boosting gelatin content and H+ ions. This gel features good water equivalency in energies from 0.3 to 20 MeV and has potential applications in the dose range of 5–100 Gy based on the selected compositions. Thus, it can cover blood irradiation and radiotherapy dosimetry applications.

PLA and its nanocomposite containing 3% chitosan nanoparticles (PLA-3CsNP) were studied to see how γ -irradiation affected their characteristics. Different doses of γ -irradiation were applied to the investigated materials under inquiry (5–40 kGy) using 60Co at ambient condition. The irradiation materials were characterized by FT-IR, GPC, mechanical tensile test, DSC, XRD, and TGA in solid and chloroform solutions. The molecular weight of the studied materials was lowered when the irradiation dose was increased, indicating that γ-irradiation had the dominating effect through oxidative degradation, and chain scission. The addition of chitosan to PLA reduces the impact of γ-irradiation, while the samples irradiated in solution showed more degradation after irradiation than irradiated solid films. Irradiation caused a decrease in tensile strength and elongation at break values. Both the melting temperature (Tm) and the glass transition temperature (Tg) decreased as the irradiation dose was increased. The cold crystallization peak temperatures were reduced when pure PLA was irradiated in solution. The thermal stability of PLA was diminished as the irradiation dose was raised, and this effect was more pronounced in samples irradiated in chloroform solution.

In the present work two homologue series of four-ring azo/ester/imine compounds; namely, 4-(4′–alkoxy–phenylazo) phenyl–4′′–(benzylidene–amino) benzoate, In, and 4–(4′–alkoxy–phenylazo) phenyl–4′′–[(pyridin-3–ylmethylene)–amino] benzoate, IIn, were prepared and investigated for their mesophase behaviour. In these two types of homologue series, the length of the terminal alkoxy group (n) varies between 6 and 16 carbons. Compounds prepared in both series were structurally characterised via thermogravimetric and elemental analyses, FTIR, 1H-NMR, and mass spectroscopy. Their mesophase transition temperatures were determined by differential scanning calorimetry (DSC), whereas, the type of the mesophase was identified by polarised light microscopy (PLM). The molecular structure–property relationship was conducted aiming to investigate the effect of replacing the terminal phenyl group in In with a pyridyl one in IIn, in addition to the effect of variation of the alkoxy chain length. Aiming to investigate the effect of inversion of the methineazo group on the mesophase behaviour of the compounds, a comparison was made between the prepared series of compounds (In) with previously prepared four rings 4-(4′-alkoxyphenylazo)–phenyl 4′′–phenyliminomethyl–benzoate phenyl-4ʹ-(4′′-alkoxyphenylazo) benzoate, IIIn. Finally, the mesophases of series IIn were compared with their corresponding three-ring analogues, 4-(4′-alkoxy phenyl −4′′-[(pyridin-4-ylmethylene)–amino] benzoate analogues (IVn).

This work deals with assessing the efficient performance of sodium caseinate (SC) as protein-based drug delivery system of niacin (NA) than carboxymethyl cellulose (CMC). In this respect the hydrogels from complexation of chitosan with sodium caseinate (SC/Ch) or sodium carboxymethyl cellulose (CMC/Ch) were prepared. The Synthesized NA free and loaded hydrogels were characterized by many techniques for examining the interaction, morphology, swelling, encapsulation efficiency (EE) and loading (L) % of niacin, as well as cytotoxicity study. The finding data showed the promising behavior of SC/Ch hydrogel than CMC/Ch hydrogel, toward the amount of loaded NA (95.6%) and in vitro slow sustained release up to 24 h. Whereas, the entrapment efficiency of the CMC/Ch to nicotinic acid was reached 85.6%, and it possessed highly initial burst release followed by a slower release up to 24 h. At pH 7.4 (simulated intestinal fluid) both hydrogels provided higher level of releasing profile to NA than pH 2.1 (gastric fluid). The NA release from hydrogels followed Fickian and non-Fickian diffusion mechanism according to pH 7.4 and 2.1, respectively. It is interesting to note that, the data obtained are higher than those obtained from literature reported hydrogel, e.g., poly (2-hydroxyethyl methacrylate). Neutral red uptake and lactate dehydrogenase assays confirmed both hydrogels have good biocompatibility and could be used as nontoxic drug delivery system. So, we recommended SC/Ch hydrogel as an effective controlled niacin drug delivery system with reducing systemic side effects and improved intestinal targeting efficiency.

In order to investigate the effect of replacing the azo group with the azomethine in the previously investigated four-ring azo/ester/azo compounds, 4-alkoxy phenylazo phenyl 4ʹ-(4′′-alkoxyphenylazo...

Chitosan (Cs) bis-aldehyde Schiff base derivatives were synthesized by condensation of Cs with three bis-aldehydes namely; butane-1,4-diyl bis(4-formylbenzoate), N,N'-(butane-1,4-diyl)bis(2-(4-formylphenoxy)acetamide) and 4,4'-(butane-1,4-diylbis(oxy))dibenzaldehyde. The prepared Cs derivatives were blended with carboxymethyl chitosan(CMC) and graphene quantum dots (GQDs) to produce semi-IPNs polyelectrolyte complexes (PECs). and characterized with respect to their molecular structure and physio-chemical properties. The antibacterial activity against H. pylori (and in vitro Inosine 5'-monophosphate dehydrogenase IMPDH inhibitory assay) was evaluated. Additionally, a preliminary in vitro assessment for wound healing was performed against PECs in which wound closure percentages, and rates were investigated indicating an accelerated wound healing compared with untreated cells. The PEC based on Schiff base PEC containing amide linkage showed the highest wound healing ability. A minimal inhibitory concentration (MIC) was obtained for the PEC sample containing Cs Schiff base derived from 4,4'-(butane-1, 4-diylbis(oxy))dibenzaldehyde at a dose of 0.98 μg/ml inhibiting H. pylori growth by 100%. Additionally, the selected above-mentioned compound was selected to test its inhibitory activity against the HpIMPDH enzyme in addition to its selectivity towards the hIMPDH2 enzyme and was found to have promising activity against the HpIMPDH enzyme with IC

Twenty four different homologues of the formula 4-alkoxy phenylazo phenyl 4ʹ-(4''-alkoxyphenylazo) benzoates (Im/n) were prepared and investigated for their mesophase behaviour. In these compounds,...

Two homologous series of the three-ring 4ʹ-(4"-alkoxy-2"-(or 3")fluoro phenylazo) benzoates terminated with 2-(or 1-) naphthyl groups (Ind&e or IInd&e), respectively, were prepared and thei...

Catalytic chemical vapor deposition (CCVD) is one of the most promising synthesis methods for economically producing large quantities of different nanocarbon structures. Here we report a systematic study of the synthesis conditions for the preparation of different nanocarbon morphological structures via acetylene decomposition over the surface of quaternary-metallic catalyst (Fe-Ni-Co-Mo) supported on MgO (Fe-Ni-Co-Mo/MgO). In particular, the effect of temperature, and the reaction time were investigated to optimize the yield, quality, size and graphitic crystallinity of the deposited carbon. The study showed a successful synthesis of: (i) a high-yield and quality bamboo-like multiwalled carbon nanotubes (b-CNT), (ii) hybrid graphene/carbon nanotubes (G/CNT), and (iii) multilayer graphene (MLG). The structures of the obtained products were characterized by HR-TEM, TGA, Raman spectroscopy, FTIR and X-ray diffraction. The results found seem essential for realizing the role of different synthesis parameters on the yield, quality, and morphology of the synthesized product. Keywords: CCVD, Carbon nanotubes, Bamboo-like structure, Hybrid graphene/CNT structure, Graphene

Introduction It is well known that the grafted multiwalled carbon nanotubes (MWCNTs) have antibacterial activity and lower cytotoxicity. Moreover, pyrazole derivatives have a broad spectrum of biological activity due to their fertile template for many medicinal drugs. On view of these findings we report herein the hybridization between MWCNTs and some pyrazole derivatives as antibacterial agents. Materials and methods Pyrazole and pyrazolone derivatives were grafted onto the surface of carboxylated MWCNTs via the reaction of carboxylated MWCNTs and the diazonium salts of pyrazoles and pyrazolones using mixed acid treatment. The insertion of the pyrazole and pyrazolone moieties was characterized by Fourier transform infrared (FTIR) spectroscopy, energy dispersion spectroscopy, transmission electron microscopy, X-ray diffraction and thermogravimetric (TGA). Results The results indicate that pyrazole and pyrazolone moieties successfully attached on carboxylated MWCNTs surface. The neat pyrazole and pyrazolone derivatives and their corresponding carbon nanotubes were tested against Staphylococcus aureus, Bacillus subtilus, Escherichia coli, and Candida albicans bacteria, and Aspergillusniger fungi. The results showed that the grafted carbon nanotubes of pyrazole and pyrazolone derivatives have better antimicrobial activity than the neat pyrazole and pyrazolone derivatives. The molecular docking studies were performed on the most potent antimicrobial compounds to investigate the existence of the interactions between the most active inhibitors and Farnesyl pyrophosphate synthase (FPPS). Conclusion The surface of the carboxylated MWCNTs was successfully grafted with some pyrazole derivatives. The antibacterial activity was investigated for the newly synthesized compounds and indicated that the grafted MWCNTs have good antibacterial activity toward some pathogenic types of bacteria.

New three groups of 2-hydroxypyridine ester-based liquid crystals named, 5-[2-(4-substitutedphenyl)diazenyl]pyridin-2-yl 4ʹ-alkoxybenzoate were synthesised. Each group differs from each oth...

Two homologous series of the three-ring azo/ester compounds 2-(or1-) naphthyl 4ʹ-(4ʹ’-alkoxy phenylazo) benzoates (Ina and IIna) were synthesised. A lateral methyl group was introduced in different positions of the alkoxy phenyl moiety, in position-2 to give series Inb and IInb and in position-3 to give series Inc and IInc. Molecular structures were characterised via elemental analyses, infrared and 1H-NMR. Their mesophase characteristics were investigated by differential scanning calorimetry (DSC) and their phases identified via polarised light microscopy (PLM). Transition temperatures were correlated with the alkoxy-chain length (n) that varies between 6, 8, 10, 12, 14, and 16 carbons. Comparative studies were first made to investigate the effect of including the extra fused benzene ring, and its orientation, into the previously investigated three-ring compounds, 4-phenyl 4ʹ-(4′′-alkoxyphenylazo) benzoates (IIIna). Investigation of the mesophase behaviour was extended to cover the effect of introducing the lateral methyl group and its position. The comparison between the present six series and their corresponding phenyl analogues IIIna,b,c, indicated that the 2-naphthyl analogues, Ina,b,c, exhibit the highest mesophase stability. Whereas, the steric effect of the protruded naphthalene group destabilises all mesophases and appear only monotropically. The results were discussed in terms of polarisability effect.

New non-symmetrical homologues series of Schiff base/ester series, 4-alkoxyphenylimino-4ʹ-phenyl-4ʹ’-alkoxybenzoates, have two terminal alkoxy groups (Im/n), were synthesised and investigated for t...

In order to study the influence of lateral Br substitution on mesophase behaviour, five homologous series of 4-substituted phenylazo phenyl 4ʹ-(3ʺ-bromo-4ʺ-alkoxyphenylazo) benzoates (Ina–e) have b...

Poly(vinylidene fluoride) (PVDF) membranes were fabricated using two different methods: the electro-spinning technique and the phase inversion process. The effect of a DMF/acetone solvent composition on the quality of the electrospun fibers of the PVDF membrane was investigated. The prepared PVDF membranes have been characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and contact angle. Uniform fibrous membranes with fiber diameters ranging mainly from 6 μm to 1.5 μm were formed from 16% (w/w) PVDF solutions in 50/50 (w/w) DMF/acetone at 30 kV voltage and 0.3 mL/h flow rate. The effect of surface morphology and hydrophilicity on anti-fouling potential was also studied and compared with flat-sheet membranes. It was found that the spun fibrous membranes exhibited the best hydrophilicity and antifouling properties with an average pure water permeability up to 400 L/m2/h, higher than that of the flat-sheet membranes, which exhibited 200 L/m2/h. Performance evaluation of the prepared PVDF membranes (water flux and organic matter retention) has been done through the use of a dead-end apparatus, where the results demonstrated the efficiency of electrospun membrane over the conventionally prepared flat-sheet membrane for utilization as a pretreatment stage of ultrafiltration and microfiltration (MF/UF), before reverse osmosis (RO) in the desalination plant.

Four new groups of Schiff base ester liquid crystal compounds, 4-(arylideneamino)phenyl-4″-alkoxy benzoates, Ina–d, were prepared and investigated for their mesophase formation and stability. An alkoxy group of variable chain length (n = 6, and 16 carbons) is attached to the terminal phenylazo benzoate moiety. Each group constitutes two homologous series that differ from each other by the polar substituent X (CH3O, H, NO2, and F). The molecular structure of the prepared compounds was confirmed via FT-IR, 1H NMR, mass spectroscopy and elemental analysis. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). For n = 6, all compounds exhibit nematic phase. Amongst them methoxy and nitro derivatives have widest mesophase range. For n = 16, nitro and flouro derivatives exhibit SmA phase, while methoxy and unsubstituted derivative are nematogenic. The change of the mesophase stability is well correlated with van der Waals volume and polarizability of the substituent X and not satisfactory with the dipole moment of the whole molecule. The mesophase behavior of binary mixtures made from each individual derivatives bearing the same substituent X but varies with alkoxy chains length is presented. Results provide insights into the role of substituent X and alkoxy chain length on the mesophase behavior within the whole composition range of the mixtures.

Three binary systems were prepared by mixing of two different mesogenic derivatives, homologues, the first is azo/ester, namely 4-alkoxyphenylazo-4&prime, phenyl-4&Prime, alkoxybenzoates (IIn+m) and the second is Schiff base/ester, namely 4-(arylideneamino)phenyl-4&Prime, alkoxy benzoates (In+m). The two corresponding analogues from both series in the binary mixtures investigated are of the same terminal alkoxy chain length. Mesomorphic properties were investigated by differential scanning calorimetry (DSC) and phases identified by polarized optical microscope (POM). Photophysical studies were investigated by UV spectroscopy connected to a hot stage. Results were discussed based on constructed binary phase diagrams. All mixtures were found to exhibit eutectic compositions, with linear or slightly linear nematic and smectic A stability/composition dependences. Geometrical parameters were predicted applying density functional theory (DFT) calculations. Twist angle (&theta, ), aspect ratio, dipole moment and the polarizability of the individual compounds were discussed and correlated with the experimental results to illustrate the enhanced the mesophase stability and the mesophase range of the mixture at the eutectic composition compared with those of their individual components.

Water pollution with toxic dyes threatens human health world-wide. Herein, we prepared an effective adsorbent hydrogel for removing toxic cationic crystal violet (CV) dye from its aqueous solutions using biodegradable polymers such as; xanthan gum (XG) and poly (N-vinyl imidazole) (PVI). The structure and morphology of the prepared XG/PVI hydrogel and CV loaded hydrogel were characterized by FTIR, FE-SEM and XRD, while thermal stability of investigated hydrogel was characterized by TGA. Adsorption experiments were carried out as functions of initial concentration of CV dye, the adsorbent dose, pH of solution, temperature, and contact time. Results were analyzed using Langmuir and Freundlich isotherm models. It is found that the data were well fitted by Langmuir model. The maximum adsorption capacity achieved was found to be 453 mg g−1 due to electrostatic, H-bonding and dipole–dipole interactions between adsorbent surface and CV molecules. The adsorption kinetic studies showed that the adsorption followed pseudo-first order and intraparticle diffusion kinetic models. Regeneration (desorption) studies showed that XG/PVI hydrogel is an interesting adsorbent for removing toxic dyes from waste water.

Four new groups of Schiff base ester liquid crystal compounds, 4-((4ʹ-substituted phenylimino) methyl)phenyl–4″-alkoxybenzoates, Ina–d, were prepared and investigated for their mesophase formation and stability. Each group constitutes four homologous series that differ from each other by the polar substituent X (CH3O, CH3, H, and Cl). Within each homologous series, the number (n) of carbons in the alkoxy chain varies between 6, 8, 10, and 12. Molecular structures of the prepared compounds were confirmed via FT-IR, 1H NMR, mass spectroscopy, and elemental analysis. The mesomorphic properties were investigated by differential scanning calorimetry and polarised light microscopy. Comparative studies between the present series and previously investigated 4-(4-substituted phenylazo)phenyl 4″-alkoxybenzoates revealed that the phenylimino mesogenic core increases the mesophase stability rather than the azo analogues.

Several binary systems made from two laterally substituted azo/ester isomers, namely 2ʺ- (and 3ʺ-) methyl-4-substituted phenyl 4ʹ-(4ʺ-alkoxyphenylazo) benzoates, where the length of the terminal alkoxy group = 8 and 16 carbons, while the other terminal substituent, X, varies between CH3O, CH3, H, Br and CN groups, were investigated using differential scanning calorimetry (DSC) and phases identified by polarised light microscope (PLM). For the sake of comparison, two another binary systems made from 2ʺ- (or 3ʺ-) methyl-4-substituted phenyl 4ʹ-(4ʺ-alkoxyphenylazo) benzoates (n = 8 and X = CH3) each was mixed with its laterally neat analogue and similarly investigated. Results were discussed on the basis of constructed phase diagrams whereby various mesomorphic properties were observed dependent on X, n, and position of the lateral methyl group. In most of the cases, the mixtures exhibited eutectic compositions, while linear or nearly linear nematic and smectic A-composition temperature dependence we...

New four-groups-based azo/ester/Schiff base liquid crystals, ((4-substitutedphenylimino)methyl)phenyl 4-[2-(4-alkoxyhenyl)diazenyl]benzoate, Ina–d, were synthesized and analyzed for their mesomorphic stability and optical activity. In these compounds, a terminal alkoxy group of variable chain length from n = 6 to n = 16 carbons is attached to the end of a phenylazo benzoate moiety and the other end of the molecules is connected to a different polar compact substituent X (CH3O, CH3, H, and Cl). FT-IR, 1H NMR, mass spectroscopy and elemental analysis were carried out for molecular structure confirmation of the prepared compounds. The mesomorphic properties were confirmed using a combination of differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The photophysical property was studied by UV-vis spectroscopy. All the prepared homologous series exhibited high thermal stability with a wide-temperature mesomorphic range. The thermal and geometrical parameters of the investigated compounds were estimated by density functional theory (DFT). The results revealed that all the compounds were not completely planar with a relatively high twisting moiety at the CHN part and their twist angles were affected by the electronic nature of the attached X group. Moreover, the calculated quantum chemical parameters as determined by the DFT approach of the investigated compounds were related to the experimentally determined values of the mesophase thermal stability (Tc) and mesophase temperature ranges (ΔTSmA and ΔTN) as well as the type of the mesophase.

Three heteroaryl pyrazole derivatives; namely 1-phenyl-3-(thiophene-2-yl)-1H-pyrazole-4-carbaldehyde, 1-phenyl-3-(furan-2-yl)-1H-pyrazole-4-carbaldehyde and 1-phenyl-3-(pyridine-3-yl)-1H-pyrazole-4-carbaldehyde were synthesized and reacted with chitosan to form Schiff bases of chitosan. All newly synthesized compounds have been characterized by solubility tests, elemental analysis, spectral (FTIR, 1H NMR) analyses, thermogravimetric analysis and X-ray diffraction (XRD). The Schiff bases were screened for their biological activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumonia), gram-positive bacteria (Staphylococcus aureus and Streptococcus mutans) and fungi (Asperagillus fumigatus and Candida albican). The results indicated that the antimicrobial activity was dependent on the type of the Schiff base moiety. Cytotoxicity of the prepared chitosan derivatives was evaluated by MTT assay and the results indicated the absence of cytotoxic activity.

Nowadays, clay minerals are used extensively in a wide range of applications as nano additives for polymeric materials. Nevertheless hydrophilic characteristics of the nano additives reduce their degree of compatibility with polymeric chains. To overcome this problem it is necessary to modify the clay in order to render its surface more organophilic prior to the intercalation of the polymeric chains between its layers. In this work the Egyptian natural clay mineral montmorillonite (MMT) was modified with two cationic organic modifiers, namely hexadecyltrimethylammonium (HDTMA) and tributyl hexadecyl phosphonium using two different procedures. The first, using the magnetic stirrer while the second using a high speed mixer at different mixing times from 0.5 up to 2.5 hr. The samples with and without organic modifiers were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM). XRD results revealed that the basal spacing of the organo-montmorillonite (OMMT) prepared using high speed mixer was larger than that using magenetic stirrer. The best result was obtained after 1.5 hr stirring in the high speed mixer. The modification of MMT was confirmed by FTIR as determined from –CH2 stretching vibration of the organic modifiers. The TGA analysis revealed that the MMT modified with tributyl hexadecyl phosphonium cation had high thermal stability than that modified with hexadecyl trimethyl ammonium cation. The amount of surfactants within organoclays were found to be found to be about 19 and 24%, respectively, for hexadecyl trimethyl ammonium bromide and tributyl hexadecyl phosphonium bromide. SEM demonstrated that the modified MMT exhibited a massive thin layered structure with some large flacks and some interlayer spaces. TEM images of the prepared organoclays showed exfoliated structure. This work proved to enhance the economical value of the Egyptian natural resources.

Polypropylene (PP) grafted with p-hydroxy-N-phenyl maleimide (pHPMA) was prepared by melt reactive extrusion in a twin screw extruder in presence of dicumyl peroxide as initiator. The content of pHPMA was varied from 1.0 up to 4.0 wt%. The grafted PP was characterized by FTIR, melt flow index (MFI), contact angle measurements, mechanical testing and thermogravimetric analysis (TGA). The non-isothermal crystallization kinetics of the neat PP and grafted PP were investigated using differential scanning calorimetry. The results showed that the MFI of the grafted PP (PP-g-pHPMA) was higher than that of PP homopolymer. The contact angle of the grafted PP was found to be decreased by increasing the monomer percent up to 3.0 wt%. Further increase of the monomer leads to an increase in the contact angle which may be attributed to the non-homogeneous distribution of the pHPMA grafted chains onto the PP surface. The thermal stability was enhanced by increasing the content of pHPMA. Grafting has not significantly affected either the tensile strength or elongation at a break point. A noticeable change in crystallization behavior of PP matrix has been observed upon grafting.

Poly(lactic acid) (PLA) containing different contents of jojoba oil (3 and 7 mass%; namely PLA-3JO and PLA-7JO), as natural plasticizer, was prepared via melt compounding. The nonisothermal crystallization behavior of PLA in the presence of jojoba oil was investigated from the glassy state. The obtained results revealed that the rate of crystallization and degree of crystallinity increased with increasing the content of jojoba. The nonisothermal crystallization kinetics was analyzed by the Avrami–Jeziorny model. Avrami exponent (n) of the PLA, PLA-3JO and PLA-7JO was found to be 4.08, 3.28 and 3.09, respectively, suggesting that the nonisothermal cold crystallizations of the plasticized PLA follow a heterogeneous nucleation and three-dimensional spherulitic growth, as occurring in the neat PLA. Furthermore, the activation energy of nonisothermal crystallization process (ΔE a) was calculated as a function of blend composition based on the Kissinger equation. It was found that the ΔE a of PLA insignificantly changed in the presence of jojoba oil. The dielectric properties of totally amorphous and crystallized plasticized PLA were also investigated for the α-relaxation process as a function of the temperature and frequency. The α-relaxation process was analyzed with Havriliak–Negami and Vogel–Fulcher–Tammann models, and fitting parameters with their evolution were discussed.

Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, 1H NMR and 13C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine. The obtained nanoparticles were uniform and spherical with average size of 9.6 ± 0.5 nm. The prepared CChG/AgNPs composites were characterized for their morphology, thermal properties, cytotoxicity and antimicrobial activity. The SEM images showed that the AgNPs are well imbedded in the CChG matrix. The thermal stability of CChG was improved with incorporation of AgNPs. The CChG and CChG/...

Siliconized epoxy matrix systems have been developed using diglycidyl ether bisphenol A LY556 epoxy resin as a base, hydroxyl-terminated polydimethylsiloxane as modifier, and γ-aminopropyltriethoxysilane as cross-linking agent together with dibutyltin dilaurate as a catalyst. Triethylene tetramine was used as a curing agent. Electrical-resistant glass (E-glass) and ultra-high-molecular-weight polyethylene (spectra)-reinforced composites are fabricated by hand-layup technique using the siliconized epoxy matrix systems. The effect of siloxane and the two fibers on the thermal and morphological characteristics of the siliconized epoxy polymer composites were studied using thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. The study reveals that the thermal stability of the epoxy systems is enhanced when siloxane is incorporated in them. Morphological studies show that the E-glass fiber reinforcement has better intermolecular adhesion to the epoxy resin than spectra reinforcement due to the presence of ionic sites.

The thermal and mesophase behaviour of all possible 1:1 mixtures (In/Im) formed from any two homologues of 4-n-alkoxyphenylazo benzoic acids bearing different alkoxy chain lengths (n and m vary between 6 and 16 carbons), were investigated by differential scanning calorimetry (DSC) and phases identified by polarised light microscopy (PLM). Phase transitions were investigated as a function of the average alkoxy chain length (=(n + m)/2) of the mixed acids. A comparison, made between the present series and previously investigated simpler analogues, 4-n-alkoxy benzoic acids, revealed that increasing the length of the mesogenic core increased the stabilities of both the smectic C and nematic phases.

A series of copoly(ether-ester-urethane)s have been synthesized from poly(3-hydroxybutyrate) (PHB) diol prepolymer, as hard segments, and copoly(e-caprolactone-ethylene glycol-e-caprolactone) (PCL-PEG-PCL) diols with different PEG block lengths, as soft segments, with/without chitin whiskers (ChW) using hexamethylene diisocyanate, as a coupling agent, in one-step polymerization. The PHB content in the resulting copolymers was 0 and 40 %, and the content of ChW was varied from 0 to 5 %. The chemical structure of the resulting copolymers was characterized by FTIR, 1H-NMR and 13C-NMR spectra. The effect of chemical structure and ChW content on the thermal properties was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The DSC data revealed that the ΔH m of both PHB and PCL-PEG-PCL slightly increases with increasing the ChW content. The cold and melt crystallization of PHB enhanced with increasing ChW content. The TG data revealed that the thermal stability of copolymers slightly enhanced at high content of ChW. The swelling behavior of the copolymers was also investigated.

The effect of introducing a lateral methyl substitution into the previously investigated laterally neat four-ring analogues, 4-substituted phenylazo phenyl 4ʹ-(4ʺ-alkoxyphenylazo) benzoates (Ina–e), on their mesophase behaviour was investigated for the newly prepared five homologous series of 4-substituted phenylazo phenyl 4ʹ-(3ʺ-methyl-4ʺ-alkoxyphenylazo) benzoates (IIna–e). Within each homologous series, the alkoxy group varies between 6, 8, 10, 12, 14, and 16 carbons, while the substituent, X, is a polar group that alternatively changes between the electron-donating (CH3O and CH3) groups, and the electron-withdrawing (Br and NO2) groups, including the unsubstituted homologues (IInc). Their mesophase stabilities were determined by DSC and phases identified by PLM. The results showed that independent of the alkoxy-chain length or the polarity of the substituent X, the nematic phase is predominant with relatively high stability and wide temperature ranges. All compounds show a good thermal stability in the mesophases domain, except the nitro and Br substituted derivatives bearing short alkoxy chain length. Comparison of the mesophase behaviour was also made between the present series and corresponding three-ring laterally CH3-substituted azo/ester analogues. UV-vis absorption spectra revealed that derivatives with electron donating or an electron withdrawing groups exhibited redshifts of the π→π* transition compared with unsubstituded derivative.

The aim of the present work was to investigate the preparation of polyelectrolyte hydrogel as potential drug carrier for antibacterial Ciprofloxacin drug (CFX), intended for controlled release formulation. Hydrogel of N-trimehtyl chitosan (TMC)/sodium carboxymethyl xanthan gum (CMXG) was prepared and ciprofloxacin was employed as a model drug to investigate the loading and release performance of the prepared hydrogel. FTIR, DSC, TGA and SEM analysis were used to characterize the TMC/CMXG hydrogel and its CFX loaded hydrogel. The results showed that the ciprofloxacin was successfully incorporated and released from the prepared hydrogel without the loss of structural integrity or the change in its functionality. The encapsulation efficiency of CFX within the prepared hydrogel was found to be increased with increasing the concentration of drug reaching about 93.8 ± 2.1% with concentration of CFX 250 µg/ml. It was shown also that the drug is entrapped within the gel without significant interaction as confirmed from FTIR spectra and DSC analysis. In vitro release study in phosphate buffer saline (PBS), indicated the steady rise in cumulative drug release with the highest release amount, reaching about 96.1 ± 1.8% up to 150 min, whereby the gel with high drug loading efficiency (3.52 ± 0.07%) displayed faster and higher release rate than that of gel containing a smaller amount of drug (0.44 ± 0.01%). The release kinetics of loaded drug followed zero-order kinetics. CFX drug loaded hydrogel showed high activity against the gram positive and gram negative bacterial strains due to the successful released of CFX from the CFX loaded hydrogel into the tested bacterial strains with the highest diameter of inhibition zone against Escherichia coli (67.0 ± 1.0) as compared to reference antibiotic, Gentamicin (28 ± 0.5). Cytotoxicity of the prepared hydrogel was examined in vitro using lung human normal cell lines and showed the highest cell viability (97 ± 0.5%) at concentration up to 50 µg/ml. Consequently, TMC/CMXG hydrogel can be proposed as new controlled release drug delivery system.

Polypropylene (PP) film activated by corona discharge treatment was grafted with methyl methacrylate (MMA) and acrylic acid (AA). The grafted PP was characterized by spectral, thermal analysis and swelling behavior which confirmed the occurrence of the grafting. The water vapor and oxygen permeability (OTR and WVTR) as well as the mechanical properties have been enhanced by grafting with both AA and MMA. The grafted PP was further immobilized with chitosan (CS) using ceric ammonium nitrate (CAN) as an initiator under ultraviolet radiation. The chitosan immobilized grafted film was characterized by FTIR, mechanical properties, thermal properties and swelling measurements. Scanning electron microscope (SEM) confirmed that the CS is bonded to the grafted PP film. The CS modified PP film has acquired enhanced antibacterial and antifungal properties.

In the present study, Antimicrobial PVC films containing different amounts of clove oil as a plasticizer were prepared using traditional casting method. The physical and mechanical properties of the plasticized PVC membranes e.g. surface wettability were investigated. The increase of clove oil content demonstrated an increase in surface hydrophilicity and elongation to break the film. The thermogravemetric analysis revealed a decrease of polymer thermal stability by increasing clove oil concentration. The antibacterial activities against four different bacterial strains (two-gram positive: Staphylococcus aureus and Bacillus cereus & two-gram negative: Pseudomonas aeruginosa and Escherichia coli were promoted by addition of clove oil. Although the natural source of clove oil, the bio-evaluation of plasticized membranes showed an increase in hemolysis percent (%) and thrombus weight. It can be concluded that the addition of clove to PVC need to further studies for applying in blood bags.

Four new groups of the di-fluoro-substituted 4-(2′-(or 3′)-fluoro phenylazo)-2-(or 3-) fluoro phenyl-4″-alkoxyphenylazo benzoates (In–IVn) were prepared and investigated for their mesophase behaviour. An alkoxy group of variable chain length (n = 6, 10 and 14 carbons) is attached to the terminal phenylazo benzoate moiety, and two lateral fluoro substituents are attached individually with different orientations to the other two adjacent rings. The molecular structures of the prepared compounds were confirmed by Fourier transform infrared spectroscopy and 1H NMR spectroscopy. The study aims to investigate the steric effect of the spatial orientation and relative positions of the two lateral fluorine atoms on the mesomorphic properties in their pure states. The mesophase behaviour was investigated via differential scanning calorimetry and mesophases were identified by polarised light microscopy. The investigation shows that these compounds exhibit high enantiotropic mesophases (SmC and N) and broad mesophase...

The curing kinetics of the modified triglycidyl isocyanurate (TGIC) with various content of N-phenylmaleimido group and carboxylated polyester (CPE) was investigated using dynamic differential scanning calorimetry (DSC). The curing kinetic behavior was well described by Sestak–Berggren (SB (m, n)) model. The m order of the curing reaction was varied from 0.229 to 0.356 and n order varied from 1.278 to 2.035, depending on the PMI content. In addition, the isoconversional method of Kissinger–Akahira–Sunose (KAS) was applied to correlate the activation energy (Ea) with the extent of cure. The obtained Ea increased with increasing phenyl maleimide content. As α increases, Ea declined up to α ≈ 0.3, then remained almost constant for α ≈ 0.3–0.8, and finally increased until completion of reaction, indicating complex reaction mechanism. The thermal stability of the cured modified TGIC/CPE was enhanced with incorporation of phenyl maleimide.