Amphiphilic Block Copolymers And Their Self-assembly

With the development of people's understanding of material science and the use of material technology, material or physical world shows more and more small size, big science and soft material, hard science. At the same time the design of materials, shows more the concept of dual coordination, That is, material seemingly in contradiction with each other, typically, hydrophilic/hydrophobic, through a certain chemical and physical design, the system will show the coordination nature of excellence. With this regards, the block copolymer shows the strong vitality. It can be self-assembly to a variety of rich structure by its own unique physical and chemical properties, ranging from a few microns, or even larger in scope. 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. Some of the aggregates have the biological simulation, studies on those aggregates can improve our understanding of the self-assembly in biological systems. Based on such a background, we synthesized two kinds of amphiphilic diblock copolymer, controlling the corresponding morphologies are achieved. Specific studies are summarized below.1. Well-defined amphiphilic block copolymers poly(styrene-b-acrylic acid) (PS-b-PAA) with controlled block length were synthesized using atom transfer radical polymerization(ATRP) and the structure , molecular weight, molecular weight distribution were characterized.2. Studies on the structural transitions from spherical to nonspherical micelles of amphiphilic block copolymer poly (styrene-acrylic acid) diblock copolymers in ethyl acetate, and explainded the possible mechanism of the morphological evolution.3. The "cherry"- or the "raspberry"-like morphology Ag nanoparticles(NPs) colloids was synthesized using amphiphilic block copolymer PS-b-PAA as templates by sonicaing or heating, with the use of linear PEI to serve as a reducing agent. The Ag NPs colloids were investigated by Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), UV-vis spectroscopy .4. Well-defined amphiphilic block copolymers PMEG-b-PMMA with controlled block length were synthesized via atom transfer radical polymerization (ATRP). The structure of diblock copolymers were characterized by ~1H NRM and IR, molecular weight distribution were determined by GPC.5. Investigated the aggregation evolution of poly (ethylene glycol)-block-poly (methylmethacrylate) in toluene with the addition of polar small-molecules and explained the possible mechanism of the morphological evolution.