Design, Synthesis And Properties Of New Type POSS-based Hybrid Nanomaterials

Polyhedral oligomeric silsesquioxane （POSS） is a kind of unique molecular hybridnanocompound at present, which has an inorganic silica core and organic side chain. It isconsidered as a new concept chemical product. The reactive functional groups introduced inPOSS impart itself the strong ability of molecular design, so POSS can be served as a goodnano component into the polymer system. On this basis, a serial of nano hybrid materials canbe designed and synthesized with new structure. This thesis includes two aspects: firstly, starpolymer POSS-（PHEMA）₈base on POSS core was synthesized via atom transfer radicalpolymerization （ATRP）, then star polymer brush POSS-（PHEMA-g-PLLA）₈was synthesizedvia ring-opening polymerization basied initiator of POSS-（PHEMA）₈. Their structure andproperties were systematically studied. The Star Polymer Brushes drug-loaded microspherewere formed, and the morphologies, drug loading performance of microsphere were studied;Secondly, POSS/SA binary composite hollow sphere and POSS/Ca/SA ternary compositesphere were prepared via electrostatic interactions between the cationic POSS and the systemof SA, and their structure, properties and application on sustained release were also studied.Main contents and results as follows:1. The star initiator octakis（2-bromo-2-methylpropionoxypropyl dimethyl-siloxy）silsesquioxane （OBPS） was synthesized via esterification reaction. Then the monodispersedstar polymer POSS-（PHEMA）₈was synthesized basied on OBPS via ATRP initiatedpolymerization of hydroxyethyl methylacrylate （HEMA）. Star polymer brushPOSS-（PHEMA-g-PLLA）₈was synthesized via ring-opening polymerization of L-lactide insolution basied on initiator of POSS-（PHEMA）₈. The star polymer and star polymer brushwere characterized by FTIR,1H-NMR, GPC, XRD, HR-TEM and TG.. The results showedthat OBPS could effectively initiated ATRP polymerization of HEMA. The star polymer wegot was monodispersed, Mn was8.66×10³¹1.90×10³, and PDI was1.13¹.25. The starpolymer is soluble in strong polar solvents such as DMF, methanol, et al. POSS-（PHEMA）₈was an amorphous polymer, and the size was60⁷0nm in solution, which the aggregate sizeof POSS was15²5nm. The POSS-（PHEMA）₈star polymer Better thermal stability. The study of POSS-（PHEMA-g-PLLA）₈showed that star polymer brush could be dissolved inordinary organic solvents such as chloroform, toluene and tetrahydrofuran et al. The Mn ofstar polymer brush was16.69×10³⁵8.86×10³, PDI was1.10¹.18. Like star polymer, Thestar polymer brush POSS-（PHEMA-g-PLLA）₈was also amorphous structure, and it size was180³60nm in chloroform, which the aggregate size of POSS was5¹0nm. The glasstransition temperature of star polymer brush was increased with the increase of degree ofpolymerization. Finaly, the Star Polymer Brushes drug-loaded microsphere were formed, Theoptimal experiment conditions of preparing spherical microsphere were: the rate of IBU andPOSS-（PHEMA-g-PLLA）₈was1:2, the rotating rate was400r/min, the concentration of PVAwas0.5％. The results showed that the size of microsphere was470⁶80nm, and theentrapment efficiency and the drug loading efficiency of microsphere were58.97%and35.58%, had a good performance of drug-loading efficiency.2. POSS/SA binary composite hollow sphere and POSS/Ca/SA ternary composite spherewas prepared via electrostatic interactions between the cationic POSS and the system of SA.The study of POSS/SA binary composite hollow sphere showed that the binary compoundhollow spheres could be formed by using POSS solution as the coagulation bath instead of thetraditional CaCl2solution. The mass ratio between POSS and SA was1.5:2.0and2.0:2.0, thespheres were formed well and the particle size of binary compound hollow sphere wasprepared between0.226⁰.421cm. Infrared Spectra showed that there were strongelectrostatic interactions between POSS and SA. X-ray diffraction, scanning electronmicroscopy, and thermo gravimetric analysis showed that POSS/SA binary composite hollowsphere became loose gradually from outside to inside until the internal was hollow, it had anamorphous structure, meanwhile its thermal stability was better than sodium alginate. Similarto the traditional sodium alginate beads, the swelling of binary composite hollow spheres wasbalanced quickly in water and HCl, while swelling rapidly in PBS solution, until crushed anddissolved. Study on POSS/Ca/SA system showed that with the increment of POSS, theparticle size of spheres became smaller and smaller. Scanning electron microscopy analysisshowed that the transaction of sphere was honeycomb structure which has a lot of holes, withthe increment of POSS, the holes became smaller and more dense. POSS/Ca/SA ternarycomposite drug-loaded sphere was prepared, and norfloxacin was used as a model drug tostudy the drug loading property of the ternary composite sphere. The results showed that POSS/Ca/SA ternary composite sphere had good and drug loading performance andcontrolled-release performance, which entrapment efficiency was35.84%, drug loadingefficiency was14.02%. The performance of controlled-release of POSS/Ca/SA ternarycomposite sphere was better than the traditional calcium alginate beads.