本論文探討PEG/RAN混合物在空間侷限效應下，表面潤濕效應對失穩分解的相分離行為的影響。首先從曇點所建立的相圖中，我們發現相分離的臨界點並未如理論與模擬的預言般，在表面潤濕的作用下會隨樣品厚度有所偏移。我們推論其來自於相分離系統的臨界點潤濕行為取決於系統中液-液-固三相的形成。因此，只有當相分離後期，兩個相的界面明銳時，潤濕效應才會明顯的發生。的確，我們對近臨界組成的失穩分解行為的形態學與動力學觀察中，發現潤濕效應的發生，有時間上的順序，與先前研究所認為的協同進行有所不同。我們利用顯微影像分析與小角光散射實驗定量探討在空間侷限下的表面潤濕效應對失穩分解的影響大致分為四階段：(1) 典型失穩分解的流體力學粗化成長；(2) 易潤濕PEG-rich相朝石英侷限壁潤濕鋪展；(3) 連接兩潤濕層間通道的成核-成長行為，且通道具臨界尺寸，在小於臨界尺寸的通道將收縮消失；(4) 相鄰通道間的合併與形狀的緩和。更重要的是，隨時間拉長，我們並未觀察到平衡潤濕層的存在，反而發生了相溶解。這個潤濕所驅動的相溶解行為調和了先前熱力學理論與動力學實驗間的不自洽的問題。具體來說，於本體（三維）中穩定的兩液相和薄膜（二維）的情況中只是亞穩的。潤濕作用會使兩相組成重新分配，達到新平衡。因此在空間侷限且存有表面潤濕作用下，真正的平衡是形成表面偏析的單相結構，而非相分離的巨觀兩相。所以相溶解行為發生。另外，又觀察到不同溫度會因表面張力驅使管道形狀緩和的速率不同，有可能作為測量液-液兩相界面張力的依據。

In this work, the surface-wetting effects on spinodal decomposition behavior of the PEG/RAN mixtures under the confinement were investigated using turbidimetry, light scattering and microscope analyses. Firstly, the critical temperature of phase separation evaluated from the cloud point has no change with sample thickness as the same with the prediction from theoretical simulation on the surface-wetting effect. It is well known that wetting effect on the critical point of phase separation depends on the formation of three-phase system (liquid-liquid-solid phase) in general. Hence, the wetting behavior will take place in the late-stage of phase separation in which the system exists the sharp interface between two phases. From the morphological observation and the kinetics of spinodal decomposition for the near-critical composition, however, the occurrence of wetting effect was found in chronological order and this phenomenon is quite different from that reported in other literatures. In this study, the surface-wetting effect on spinodal decomposition in the confined space would be elucidated further with considering the mechanisms of structural evolution for a phase-separating system. In summary, the structural change with time during spinodal decomposition process can be divided into four stages: (1) typical hydrodynamic coarsening of spinodal decomposition; (2) wetting PEG-rich phase spreading on the quartz confined wall; (3) the nucleation-growth behavior of channels connecting to two wetting layer (there exists a critical radius, so the channels will shrink and then disappear if the channel is smaller than the critical radius); (4) the closure and shape relaxation of channels. Most importantly, the existence of equilibrium wetting layers with time was not observed in this work, whereas the phase dissolution occurs. The wetting-driven phase dissolution behavior harmonizes the inconsistency between the thermodynamic theory and kinetic experiments. Strictly speaking, the two-phase separation should be stable in the bulk (3D), while it is considered to be metastable in thin film (2D). The wetting effect will reconstruct the two-phase composition, and then this will reach a new equilibrium state. Therefore, for the surface-wetting effect in confined space, the real equilibrium state may mean that the formation of one-phase structure with surface segregation is rather important than that of two-phase phase separation. Therefore, the phase dissolution has to be expected to occur under these arguments. On the other hand, the shape relaxation rate of channels is found to correlate with the temperature and this fact might be considered due to the change in surface tension. To concern further about the effects of surface tension on the mechanism of liquid-liquid phase separation is very important in the near future.

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