Phase change and fluorescence properties of the polydiphenylacetylene derivative, poly[1-phenyl-2-(p-trimethysilyl) phenylacetylene] (PTMSDPA), were investigated according to the thermally induced phase separation (TIPS) method. 1,4-dioxane was selected as the theta solvent from solvents having solubility parameters similar to that of the polymer, and the phase diagram of the solution of PTMSDPA/1,4-dioxane was derived using the cloud-point method. A critical point appeared at a concentration of 0.88×10^-2 M and a temperature of 51.6 ^oC as the theta condition. During the cooling process, a significant fluorescence enhancement occurred near the critical point, because collision quenching and vibration relaxation in the polymer chain, which causes non-radiative emission decay, are restrained by the abrupt phase separation between the polymer and the solvent. This study provides a tentative method for producing highly fluorescent nanoparticles and microporous membranes by applying TIPS to fluorescent conjugated polymers.

열유도 상분리에 따른 폴리디페닐아세틸렌 유도체인 poly[1-phenyl-2-(p-trimethysilyl)phenylacetylene](PTMSDPA)의 상변화와 형광특성을 조사하였다. 폴리머와 비슷한 용해도상수를 가지는 용매들로부터 1,4-다이옥산이 theta solvent로 선정되었고, cloud-point법을 통해 PTMSDPA/1,4-다이옥산(1,4-dioxane) 용액의 phase diagram이 도출되었다. Theta condition으로 농도 0.88×10^-2 M, 온도 51.6 ^oC에서 임계점이 나타났다. 냉각과정에서 임계점 부근에서 급격한 형광증대현상이 나타났으며, 이는 비방사성 형광 감쇠를 초래하는 폴리머 사슬 내의 충돌소광 및 진동완화가 폴리머와 용매사이의 급작스러운 상분리에 의해 억제되었기 때문이다. 본 연구는 형광공액고분자에 열유도 상분리법을 적용하여 초고형광성 나노입자 및 다공막을 제조할 수 있는 잠정적인 방법을 제시하고 있다.

Keywords: thermally induced phase separation, polydiphenylacetylene, phase diagram, theta solvent, fluorescence emission.