Fabrication Of A Novel Small Molecular Colloids And Syntheses Of Several Macromolecules For Colloidal Assemblies

Colloids have attracted much research interest in the past decades due to their important and wide applications in diverse fields such as catalytic chemistry, materials preparation, and biomedicine. In spite of diverse compositions of colloidal assemblies there are two major groups of colloidal systems: One is composed of classic “small molecule surfactants”. The other is consisted of polymers known as the “macromolecular surfactants”. In solution they can self-assemble into multiple kinds of ordered structures such as micelles, vesicles, and so on.In the current study, a variety of colloidal assemblies constituted of small molecules and macromolecules is concerned. Specifically, the present work includes the following aspects:1. The formation of unilamellar vesicles was successfully established by the addition of hydrotropic salt p-toluidine hydrochloride(PTHC) to solutions of the anionic surfactant sodium dodecyl sulfate(SDS) at high salt concentrations. Upon dilution or heating these vesicles can transform into long, flexible wormlike micelles. In this process, the solutions switch from the aqueous solution of bluish and nearly Newtonian liquids with low viscosity to clear and viscoelastic solutions with an ability to trap bubbles, which was called “dilution-thickening” or “thermo-thickening”. Rheological techniques, laser light scattering(LLS), transmission electron microscopy(TEM), micro-differential scanning calorimetry(micro-DSC), and transmittance measurements were used to confirm the formation of vesicles and their reversible transformation with WLMs. Finally, a tentative mechanism for the reversible transition was proposed to explain the results.2. The anionic polyelectrolyte polyethylene glycol-b-poly(sodium p-styrenesulfonate)(PEG-b-PSSNa) was successfully synthesized via the atom transfer reversible polymerizations(ATRP). First, PEG-Br, the macroinitiator, is synthesized via acyl bromide reaction of polyethylene glycol terminated by monohydroxyl(PEG-OH) and 2-bromoisobutyryl bromide, which is confirmed by the proton nuclear magnetic resonance spectroscopy(~1HNMR) and infrared spectroscopy(IR). Then,using mixed solvent of water and methanol, PEG-Br as macroinitiator, CuBr/2,2,-bipyridine(bpy) as catalytic system,and sodium p-styrenesulfonate as monomer, the PEG-b-PSSNa diblock copolymer is prepared. Its molecular weight and molecular weight distribution are characterized by means of ~1HNMR and gel permeation chromatography(GPC).3. The cationic polyelectrolyte PEG-b-PQDMA where PQDMA is poly(2-(dimethylamino)ethyl methacrylate) fully quaternized with methyl iodide was successfully prepared via the following two steps. Using ATRP technology with PEG-Br as macroinitiator, CuBr/bpy as the catalytic system, isopropanol as the reaction medium, and 2-(dimethylamino)ethyl methacrylate as monomer the diblock copolymer poly(ethylene oxide)-b-poly(2-(dimethylamino)ethyl methacrylate)(PEG-b-PDMAEMA) was synthesized. Then the diblock copolymer was quaternized by methyl iodide in DMSO. The above products are characterized by means of ~1HNMR and GPC.4. Preparation of the cationic polyelectrolyte polyethylene glycol-b- poly 4-vinylpyridine(PEG-b-P4VP) was successfully established. First, Using PEG-OH and 2-chloropropionyl chloride the macroinitiator PEG-Cl was prepared, which is confirmed by ~1HNMR and IR measurements. Second, the ATRP ligand was Me6 Tren was synthesized as previous reports. Then the ATRP of 4-vinylpyridine was obtained with by method of initiating polymerization of monomer 4VP successfully obtained with PEG-Cl as macroinitiator and CuCl/Me6TREN as catalyst. Its molecular weight and molecular weight distribution are characterized by means of ~1HNMR and GPC.5. The polyelectrolyte poly(tert-butyl methacrylate)-b- poly 4-vinylpyridine(PtBA-b-P4VP) was successfully prepared via the following two steps. The macroinitiator, poly(tert-butyl methacrylate)(PtBA-Cl), was first synthesized via ATRP technique, using 2-chloro propargyl propionate(PCP) as the initiator, CuCl/pentamethyldiethylenetriamine(PMDETA) as catalytic system,.Then the diblock copolymer PtBA-b-P4VP was further prepared with CuCl/Me6TREN catalytic system. GPC and ~1HNMR measurements confirmed the complete synthesis.