Khalid A. Ibrahim

Preparation of hydrophilic polymeric nanolayers attached to solid surfaces via photochemical and ATRP techniques

Three different hydroxyl functional propylene/10-undecen-1-ol (PP-OH) copolymers were attached photochemically to a photoreactive benzophenone derivative that was bound to SiO2 surfaces via a silane anchor. As a result of the photochemical reaction, thin layers of the PP-OH polymers were covalently bound to the surface. The thickness of the layers was a function of the molecular weight of the polymer. Poly(2-hydroxyethymethacrylate) (PHEMA) nanolayers were successfully grafted onto the PP-OH-modified silicon wafers (PP-OHMSW) via surface-initiated atom-transfer radical polymerization (ATRP) in aqueous media at ambient temperature. Kinetic studies revealed an increase in thickness with reaction time, indicating that the polymerization process has some “living” character. Contact angle measurements showed a reduction in the water contact angles of the resulting PP-OHMSW-PHEMAs, indicating a more hydrophilic surface tension state. The coupling of ATRP initiator to the hydroxyl groups on the PP-OH polymers, the surface-initiated ATRP, and the grafting of PHEMA onto the PP-OHMSW were confirmed by Fourier transform infrared spectroscopy (FT-IR). The grafted polymeric layers provide a platform for further surface modification through the functionalization of the hydroxyl groups of the PHEMA polymers.

Preparation of Chito-Oligomers by Hydrolysis of Chitosan in the Presence of Zeolite as Adsorbent

An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers) in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC/MS), and ninhydrin test.

Preparation and Characterization of Alkyd Resins of Jordan Valley Tomato Oil

Tomato seeds represent a large waste by-product from the processing of tomatoes into products such as tomato juice, sauce and paste. One potential use for these seeds is as a source of vegetable oil. In this study, the seed oil of tomato obtained from Jordan Valley was extracted and analyzed to determine its physicochemical properties. The characteristics (iodine value, acid value, refractive index and saponification value) of the oils were determined. Tomato oil has an iodine value of 123, a refractive index of 1.467, a saponification value of 192, and an acid value of 2.3. Our alkyd resins results showed that the extracted tomato seed oil can be qualified to be used in the synthesize of alkyd resin. Three grades of tomato-based alkyd resins modified by varying the percentage of tomato seed oil contents were prepared according to the alcoholysis-polyesterification process. Fourier transform infrared, proton nuclear magnetic resonance spectroscopy and differential scanning calorimetry were employed to identify the structure of the resulting resins.