| 초록 |
Recent advances in controlled polymerization techniques allow the precise control over chains size, uniformity, shape, composition, microstructure and functionality of macromolecules. Controlled/"living" radical polymerization (CRP) and metallocene catalyzed olefin polymerization can be two representative examples. For olefins, single site catalysts like metallocene catalysts have been widely investigated for the commercial success of the system. For example, bimodal linear low density polyethylene (LLDPE) with inverse comonomer distribution was prepared through hybrid metallocene catalyst system in a single reactor. For polar monomers, controlled/"living" radical polymerization (CRP) has opened a way to control the architectures and functionalities of polymers in free radical process. Atom Transfer Radical Polymerization (ATRP), Nitroxide Mediated Polymerization (NMP) and Reversible Addition and Fragmentation Transfer are three main techniques for CRP. ATRP uses transition metal as catalyst, which requires the removal of the metal from resulting polymer after polymerization. Immobilized/soluble hybrid catalyst system has been developed for this purpose. Polyolefin and CRP techniques can be combined to provide polyolefins with polar segments. The techniques afford a way to design polymer architectures with controlled reactivity, which become a critical step for its success in many applications including nano-materials, bio-/medical- devices, electronic devices, organic/inorganic nano-hybirds. |
