Thin (~650 nm) and ultrathin (~50 nm) films of neat PMMA and PMMA containing 5 wt% of methacryl-polyhedral oligomeric silsesquioxane were prepared in this work. The effects of film thickness and POSS on glass transition temperature (Tg) and isothermal physical aging were investigated by means of differential scanning calorimetry (DSC). Tg depression was observed as film thickness was decreased and Ma-POSS molecules were incorporated. Enthalpy relaxation (ΔHRelax) due to the isothermal physical aging was reduced by ultra-thin film thickness and the addition of Ma-POSS. KWW (Kohlrausch-Williams-Watts) equation was used to fit ΔHRelax vs. aging time data providing the fitting parameters; maximum enthalpy recovery (ΔH∞), relaxation time (τ) and non-exponentiality parameter (β).

순수 PMMA와 methacryl-polyhedral oligomeric silsesquioxane(Ma-POSS)를 5 wt% 첨가한 PMMA를 박막 (~650 nm)과 초박막(~50 nm)으로 제조하였으며, 유리전이온도(Tg)와 등온 물리적 시효에 미치는 박막의 두께에 미치는 POSS의 첨가 효과를 시차주사열량계(DSC)를 이용하여 조사하였다. 초박막화와 Ma-POSS의 첨가로 인해 Tg 감소가 관찰되었다. 또한 등온 물리적 시효에 의한 엔탈피 완화값(ΔHRelax)도 초박막화 Ma-POSS를 첨가하였을 때 감소하였다. 시효시간에 따른 ΔHRelax 데이터에 KWW(Kohlrausch-Williams-Watts)식을 적용하여 최대 엔탈피(ΔH∞), 이완시간(τ) 그리고 이완시간의 분포상수(β)를 결정하였으며 이를 비교 분석하였다.

Keywords: PMMA; thin film; POSS; glass transition temperature; isothermal physical aging.