Synthesis Of The Block Copolymers And The Nanomaterials Based On The Block Copolymers

Block copolymer was produced by joining two or more chemically distinct polymer blocks, each a linear series of identical monomers that may be thermodynamically incompatible (like oil and vinegar). Block copolymers have attracted considerable attentions because of their unique behaviors and potential applications in thermoplastics, surfactants, modifiers, dispersants, and solubilizer etc. With the development of the living polymerization, a large number of novel well-defined block copolymers with controlled molecular weights and narrow molecular weights distributions were prepared.Block copolymers often phase separate for the thermodynamically incompatible between the chains. As the blocks are covalently bonded to each other, so the phase separation was limited in micro-scale. In a selective solvent, block copolymers can self-assemble into micelles. Polymer micelles have been extensively investigated for their potential applications in drug delivery, separation, catalyst, and nanomaterials field. At the same time, block copolymers can also self-assemble with the inorganic precursors to obtain nanocomposite materials. And the composite materials obtained may have a wide variety of potential applications ranging from photo catalyst to biosensors to fuel cell membranes. So it draws considerable attention recently.A series of block copolymers have been synthesized by the combination of the living polymerization. However, the combination of enzymatic polymerization and another living polymerization have rarely been reported to the best of our knowledge. So in the thesis we synthesized a series of polymers with new architectures by the combination of enzymatic polymerization and the Schiff base reaction, and enzymatic polymerization and the living anionic polymerization. The synthesis of SiO2-C nanocomposite materials by the polymeric micelle template has rarely been reported yet, not to mention the block copolymer was used as the carbon micelles at the same time. So in the thesis we synthesized SiO2-C nanocomposite materials by using the PEO-b-PAN block copolymer micelles both as template and carbon precursor. We also synthesize a new type of SiO2-C nanocomposites templated from PEO-b-PAN phases. In the thesis we design a lower temperature strategy to synthesis mesoporous materials at the same time. The brief contents and results of the thesis are as follows: PartⅠ:Design and Synthesis of Polymers1. Polyphenols containing Schiff base pendent groups, poly(4-[benzylidene-amino]-phenol) (PBP) and poly(4-[(anthracen-9-ylmethylene)-amino]-phenol) (PAP), have been synthesized via the combination of Schiff base reaction and enzymatic polymerization using horseradish peroxidase (HRP) as catalyst. The polymers were characterized by GPC, IR,1H NMR, and UV spectroscopy. It shows that PAP has a large red-shift of 86 nm compared with polyphenols, indicating the Schiff base pendent groups remarkably increase the conjugation lengths of polyphenols.2. Water-soluble polyphenol-graft-poly(ethylene oxide) (PPH-g-PEO) copolymers were prepared via the combination of enzymatic polymerization and living anionic polymerization. The polymers were characterized by using GPC, SLS, IR, UV, and 1H NMR spectroscopy. The results show that the PPH-g-PEO graft copolymers are soluble in several common solvents, such as water, ethanol, N, N-dimethyl formamide, tetrahydrofuranan, dmethylene dichloride. The solubility of the PPH-g-PEO graft copolymers is improved significantly compared with that of polyphenol.PartⅡ:Preparation of Nanomaterials from the Block Copolymer Template.3. Highly ordered mesoporous silicas have been successfully synthesized by using Poly(ethylene oxide)-Poly(a-methyl styrene)-Poly(ethylene oxide) (PEO-PMS-PEO) triblock copolymers as a new templates via the evaporation-induced self-assembly (EISA) approach. The obtained mesoporous silicas have been characterized by TEM and SAXS in detail. The results show that they display a highly ordered body-centered cubic framework. The mesoporous structure was retained after removing the block copolymer with framework shrinkage of only 8.7%.4. Mesoporous carbon have also been successfully synthesized by using PEO-PMS-PEO triblock copolymers as templates, low molecular weight phenolic resin (resol) as carbon precursor via the evaporation-induced self-assembly (EISA) approach. The mesoporous carbons were characterized by TEM and SAXS in detail, and the results show that they display a highly ordered face-centered cubic mesostructure, and the mesostructure retained after removing the block copolymer with framework shrinkage of only 5.6%. 5. Amphiphilic block copolymer poly(ethylene oxide)-polyacrylonitrile (PEO-b-PAN) have been synthesized through the combination of anionic polymerization and atom transfer radical polymerization (ATRP). The copolymer was used as supramolecular templates and carbon precursors for the formation of SiO2/PEO-b-PAN nanocomposite through the evaporation-induced self-assembly (EISA) approach. Subsequently, the nanocomposite was heat-treated at 300℃under air to set the structure and then calcined at 1000℃under nitrogen to form nanostructured SiO2-C composite. The results show that the SiO2-C nanocomposite displays an ordered lamellar nanostructure.6. Block copolymers PEO-b-PAN were self-assembled into micelles with PEO as the shell and PAN as the core in aqueous solution. Silica was loaded into the micellar shells after introduction of acidic tetraethoxysilane solution by using these micelles as templates. After preoxidated at 300℃in air and calcined at 1000℃in nitrogen, the SiO2-C nanocomposite particles were prepared. The results show that the SiO2-C nanocomposite displays a particle nanostructure with a carbon core in a silica shell. Its diameter was 55±5 nm...