Block Copolymers And Their Micellization

The self-assembly of block copolymer is an emerging research areas in nanotechnology. Block copolymers can self-assemble into nano-spheres, rods, vesicles and large compound micelles and other forms in solution. With the depth understanding of self-assembly process, block copolymer for the potential applications in many fields was facilitated, such as drug delivery, separation, electronics and catalysis.Amphiphilic diblock copolymer, the hydrophobic chain and the hydrophilic chain are connected together by the chemical bonds, when it is dissolved in the solution, their synergistic effect, showing the rich self-assembly behavior. Amphiphilic diblock copolymer, like small molecular surfantants, lipid amphiphilic molecular in selective solutions can self-assembled to all kinds of aggregates. The morphologies include microspheres, nanutube, wormlike, cylindrical, vesicles, and lamellar, its size from nano-to micron-level even greater. Double hydrophilic block copolymer is a special class of amphiphilic block copolymers. Usually, one block of the DHBCs is water-soluble to promote the polymer solution and decentralization, and the other block can change from hydrophilic to hydrophobic block by changing the external environment conditions, such as temperature, pH, and ionic strength or by complex with the opposite charged metal ions, small molecules and polymer chain, to have the environmentally sensitive micellization. As the self-assembly behavior of their external environment and the sensitivity of the response, it is also known as smart materials.Based on such a background, we synthesized a series of amphiphilic diblock copolymer, controlling the corresponding morphologies are achieved. Specific studies are summarized below.1.Amphiphilic block copolymers poly(styrene-b-acrylic acid) (PS-b-PAA) were synthesized using atom transfer radical polymerization(ATRP) and the structure were characterized by NMR. The amphiphilic block copolymer polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles is employed as template, with the aid of sonicating, using solvent-derived effects,the cage-like silver colloidal nanoparticles (NPs) were synthesized successfully. The stable silver colloidal nanoparticles were characterized by Transmission Electron Microscope (TEM), X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS).2. The PMEG-Br macroinitiator was synthesized by esterification of the hydroxyl terminal of PMEG with 2-Bromopropionyl bromide, which was subsequently used in the preparation of halo-terminated poly(ethylene glycol)monomethyl ether-block-poly(tert-butyl acrylate) (PMEG-b-PtBA) diblock copolymers under Atom transfer radical polymerization (ATRP) conditions by using CuBr/Me6TREN as catalysts. Then, the copolymer was hydrolyzed under excess Trifluoroacetic acid (TFA). So, we got double-hydrophilic block copolymers PMEG-b-PAA.The molecular weight and structure of aforementioned copolymers was characterized by gel permeation chromatography (GPC), infrared spectrometry (IR), hydrogen nuclear magnetic resonance ('H-NMR).The results indicated that the double hydrophilic block copolymers PMEG-b-PAA was synthesized successfully and good monodisperse. Investigated the aggregation evolution of PMEG-b-PAA in water with the addition of CTAB and explained the possible mechanism of the morphological evolution.3.Well-defined amphiphilic block copolymers PMEG-b-PS were synthesized via atom transfer radical polymerization (ATRP). The structure of diblock copolymers were characterized by NRM and IR, molecular weight distribution were determined by GPC.