副鎖の障害とアルキル置換,結合オリゴマーの相変異. P3ATにおけるサイドチェーンの融解との関係
M David Curtis1, John I Nanos, Hyunsik Moon
1Department of Chemistry and the Macromolecular Science and Engineering Program, The University of Michigan, Ann Arbor, Michigan 48109, USA. mdcurtis@umich.edu
Journal of the American Chemical Society
|November 9, 2007
まとめ
アルキル置換されたビチアゾールオリゴーマーの中には,融点以下で結晶・結晶相移行 (アルファ・ベータ) を示すものもあります. この移行は,n-パラフィンやポリ−3-アルキルチオフェンと類似した,ガウチ欠陥の増加を伴う.
科学分野:
- マテリアルサイエンス 材料科学
- ポリマー化学のポリマー化学について
- 固体物理 固体物理学
背景:
- 結合した背骨と柔軟なサイドチェーンを持つオリゴマーは,電子アプリケーションに興味があります.
- そのような材料の相変異は,その特性や性能に大きく影響を与える可能性があります.
- 熱移行の性質を理解することは,材料の設計と加工に不可欠です.
研究 の 目的:
- アルキル置換された2,2'-ビチアゾールとビチアゾール-チオフェンのオリゴーマーで観察された熱変遷を調査する.
- これらの移行に伴う構造的,動的変化を明らかにする.
- 観察された現象を,n-パラフィンやポリー・3-アルキルチオフェンなどの関連物質と比較する.
主な方法:
- 熱分析のための差分スキャニング熱計 (DSC).
- 温度変数フーリエ変換赤外線 (FTIR) スペクトロスコピー.
- マジック・アングル・スピニング1H核磁気共振 (MAS NMR) スペクトロスコピー.
- 紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.紫外線可視 (UV-vis) スペクトルスコピー.
- 構造的特徴化のためのX線微分法 (XRD).
主要な成果:
- DSCの痕跡では,融点以下で,エンドサーミック移行 (alpha --> beta) が観察されました.
- FTIRは,移行時に gauche 欠陥の増加を示したが,MAS NMRは,融解までサイドチェーン運動が限られていることを示した.
- UV-VISスペクトルは,アルファ --> ベータ移行を通して,結合された脊椎の平面性を確認しました.
- XRDデータは,結晶-結晶相移行メカニズムを支持した.
結論:
- 観測された熱変遷は,サイドチェーン障害によって引き起こされる結晶-結晶相変遷である.
- この振る舞いは,n-パラフィンとポリ・3-アルキルチオフェン (P3ATs) の相変化に類似しています.
- P3ATにおける"サイドチェーンの溶解"は,結晶分子の内部での結晶-結晶相移行としてよりよく説明できます.
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