科研之友
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摘要
Structure and dynamics of two microphase-separated norbornene block copolymers containing one comb-like component are investigated by X-ray scattering, relaxation spectroscopy as well as differential scanning calorimetry. It is shown that two self-assembling processes on different length scales coexist for these copolymers leading to hierarchically structured systems. Microphase separation of both block copolymer components appears on a scale of 20-25 nm while norbornene main and long semifluorinated side chains of the comb-like block nanophase separate within their domains on a scale of about 3 nm. This hierarchical structure is accompanied by a complex relaxation behavior which is characterized by two glass transitions. The glass temperature of the block with long bulky side chains is expectedly lower due to internal plasticization. An additional relaxation process showing typical features of a dynamic glass transition is related to an independent dynamics in small nanodomains formed by long aggregated side chains similar to the findings for many other comb-like polymers. Indications for the disappearance of the nanophase separation of main and semifluorinated side chains at high temperatures are discussed.
- 出版日期2011-2-22
