اصلاح پلي وينيل الكل به منظور سنتز كوپليمرهاي فعال نوري جديد حاوي آمينو اسيد L- فنيل آلانين و تهيه نانو كامپوزيت هاي پلي وينيل الكل/تيتانيوم دي اكسيد و بيو نانو كامپوزيت هاي پلي ﴿آميد-ايميد﴾/تيتانيوم دي اكسيد حاوي آمينو اسيد L- ايزولوسيون

چكيده انگليسي :

Modification of Poly vinyl alcohol for Synthesis of Novel Optically Active Copolymers and Preparation of Poly vinyl alcohol Titanium Dioxide Nanocomposites and Poly amide imide Titanium Dioxide Bionanocomposites Abdolvahid Barati a vahid barati@gmail com 9 February 2011 Department of Chemistry Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Prof Shadpour Mallakpour E mail mallak@cc iut ac ir mallak777@yahoo com mallakpour84@alumni ufl edu Abstract In this project at first poly vinyl alcohol PVA was chemically modified by the introduction of differentamount of N phthaloyl L phenylalanine The modification was carried out by the reaction of PVA hydroxylgroups with 2S 3 phenyl 2 phthalimidylpropanoyl chloride using N N dimethyl acetamide lithium chlorideas a reaction media The novel copolymers obtained were characterized by spectroscopic techniques elemental analysis X ray diffraction and thermal methods Optical rotation and viscosities were alsomeasured The degree of esterification was determined by 1H NMR The influence of reagent molar ratio onthe degree of modification was also evaluated The vinyl 3 phenyl 2 phthalimidopropanoate content in thecopolymer was attained up to 52 Thermal stability of the copolymers was checked by thermogravimetricanalysis and differential thermogravimetric analysis All copolymers displayed improved thermal stabilitycompared to the parent polymer In the second part the surface of titanium dioxide TiO2 nanoparticles wasmodified with aminopropyltriethoxy silane as a coupling agent Then a new kind of poly vinylalcohol titanium dioxide PVA TiO2 nanocomposites coating with different modified TiO2 loading wereprepared under ultrasonic irradiation process Finally these nanocomposites coating were used for fabricationof PVA TiO2 films via solution casting method The resulting nanocomposites were fully characterized byfourier transform infrared spectroscopy FT IR powder X ray diffraction XRD thermogravimetricanalysis derivative thermal gravimetric TGA DTG transmission electron microscopy TEM scanningelectron microscopy SEM and atomic force microscopy AFM The TEM and SEM results indicated thatthe surface modified nanoparticles were dispersed homogeneously in PVA matrix on nanoscale and based onobtained results a possible mechanism was proposed for ultrasonic induced nanocomposite fabrication TGAconfirmed that the heat stability of the nanocomposite was improved UV visible spectroscopy was employedto evaluate the absorbance and transmittance behavior of the PVA TiO2 nanocomposite films in thewavelength range of 200 800 nm The results showed that this type of films could be used as a coating toshield against UV light Finally Novel poly amide imide TiO2 bionanocomposites containing L isoleucinemoiety in the main chain were prepared via a simple and inexpensive ultrasonic irradiation process Poly amide imide as a source of polymer was synthesized by direct polycondensation reaction of N trimellitylimido L isoleucine with 4 4 diaminodiphenylsulfone in the tetrabutyl ammoniumbromide triphenyl phosphite as a green solvent system Due to the high surface energy and tendency foragglomeration the surface of TiO2 nanoparticles was modified with aminopropyltriethoxyl silane Theresulting hybrid bionanocomposites were characterized by FT IR spectroscopy UV visible spectroscopy X ray diffraction field emission scanning electron microscopy FE SEM transmission electron microscopy TEM and thermogravimetric analysis TGA Through TEM photographs it can be found that the surfacemodified TiO2 nanoparticles with diametric size of less than 40 nm uniformly dispersed in the PAI matrix Keyword Poly vinyl alcohol Modification of polymers Optically active polymers Nanocomposites Bionanocomposites Titanium dioxide

براتي، عبدالوحيد

اصلاح پليمرها