| Understanding the self-organization in biological systems and controlled fabrication of materials with small size have become very attractive fields for science and technology. With this regards, the block copolymer shows the strong vitality. The block copolymers can: i) self-assemble into aggregates with biomimetic morphologies in selective solvents (Science 1996, 272, 1777-1779); ii) controllably construct hierarchical metal nanostructures on block copolymer thin film scaffolds (Nature 2001, 414, 735-738); iii) fabricate photonic crystals in bulk (Adv. Mater. 2001, 13, 421-425). The tailoring of block copolymers with novel architectures and controlling the corresponding self-assembled morphologies are very important topics. In this thesis, three kinds of block copolymers were controllably synthesized and the novel multiple morphologies in solutions were obtained depending on various conditions. The relatively detailed summaries were as follows.1. Two kinds of novel triblock copolymers have been synthesized by Living /Controlled Radical Polymerization. The PS (polystyrene)-Z>-PEO (poly(ethylene oxide))-Z>-PS and PS-6-P4VP (poly(4-vinylpyridine))-6-PS (P4VP-6-PS-6-P4VP) triblock copolymers were synthesized through Atom Transfer Radical Polymerization (ATRP) and Reversible Addition Fragmentation Chain-Transfer Polymerization (RAFT), respectively. In addition, the PLA (polylactide)-i-PEO-6-PLA triblock copolymers were prepared by by ring-opening polymerization of D, L-lactide in presence of a,o)-dihydroxy-terminated PEO and a small amount of stannous octoate.2. The aggregation of PS4-&-PEO227-&-PS4 triblock copolymer (the subscripts represent the degree of polymerization) in aqueous solution was investigated by 'H NMR, Fluorescence Probe, and TEM techniques. The experimental results showed that the aggregation did occur and the critical concentration for aggregation was about 0.01g/L. When the concentration of colloid solution was 10 g/L, the spherical aggregate with a highly polydispersity and radii ranging from 100nm to 500nm was observed. The possible structures of primary micelles and micellar aggregates were proposed.3. The "crew-cut" aggregation behavior of BAB triblock copolymers with water-soluble middle block A in water were investigated by TEM, AFM, and DLS methods. The polymers used are PS-6-PEO-6-PS and PS-6-P4VP-6-PS triblockcopolymers, which have relative higher contents of hydrophobic end block PS. The novel multiple morphologies were observed, including short and branched rods, bicontinuous rods, worm-like micelles, lamellae, vesicles, large compound vesicles, large compound micelles, and so on. This spectrum of self-assembled morphologies basically covers the morphologies obtained from small molecular surfactants and diblock copolymers in solutions. The morphology can be controlled by the altering such parameters as copolymers and composition, solvents, concentration, pH, temperature, annealing, and the presence of additives. These factors can influence the balance of three major forces acting on the self-assembly system. These include the stretching of the core-forming blocks, the inter-coronal chain interactions, and the interfacial energy between the solvent and aggregate core.4. The mechanism of morphology transition was primarily confirmed. The adhesive collision of spheres resulting in rods; the flattening of rods into lamellae; and bending of lamellae to "bowl-like" and to vesicles. Basically, this transition mechanism for BAB triblock copolymer "crew-cut" is same to that for small molecular surfactants and AB diblock copolymer aggregates. However, the chain architecture of BAB contributed the departure, for example, for BAB aggregates, short and branched and inter-linked rods flattened into net lamellae, then rearranged into lamellae.5. The spherical micelles of PLA-6-PEO-6-PLA triblock copolymers were prepared by adding water into copolymer solutions. The surface visico-elasticity of aggregates cast on the mica was...
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