本研究第一部份合成不同聚合度的聚乳酸(PLLA, 聚合度= 60~ 468)與聚丙二醇(PPG, 聚合度= 17, 34, 69)三團聯共聚物(PLLA-PPG-PLLA)。使用偏光顯微鏡方法探討不同聚合度的PLLA鏈段以及不同聚合度的PPG鏈段，對球晶成長動力學參數的影響。以Hoffman-Weeks方法估計平衡熔點(Tm˚)與增厚係數(δ)，再估計平衡晶片厚度(Lc)，並討論平衡晶片厚度與PLLA鏈段及PPG鏈段聚合度之標度關係。

由Hoffman-Weeks方法可知共聚物的平衡熔點隨著PLLA鏈段聚合度變小而降低，且增厚係數會隨著共聚物PLLA鏈段聚合度愈大而下降。接著利用平衡熔點求出平衡晶片厚度，討論平衡晶片厚度和PLLA鏈段聚合度之冪次關係的標度指數α，與非平衡晶片厚度所求得之標度指數α’比較，發現α較α’為大(非平衡時過冷度，其範圍在30 K到90 K之間) ；而平衡晶片厚度所求得之標度指數α，較理想理論值大。討論平衡晶片厚度與PPG聚合度之冪次關係的標度指數β，其值較非平衡晶片厚度與PPG鏈段聚合度的標度指數β’小;再將平衡晶片指數β絕對值與理論值的絕對值作比較，發現較理論值小，因為理論值皆忽略兩鏈段相連處柔軟度不同造成的局部化自由能(floc)以及結晶相硬段與非晶相軟段界面處之自由能(fint)。

另一部份將聚乳酸的聚合度固定在小範圍內(聚合度= 254~264)，合成一系列聚乳酸與聚乙二醇( PEG, 聚合度=23, 46, 91)三團聯共聚物(PLLA-PEG-PLLA)。將此三團聯共聚物製備成微胞溶液，使用螢光探針法測量臨界微胞濃度，並使用動態光散射儀測量微胞粒徑，探討微胞半徑與親疏水鏈段聚合度的標度關係，利用紫外光/可見光分光光度計測得三團聯共聚物微胞溶液中包覆藥物Vitamin K3的濃度，計算藥物分配係數與藥物荷載率。

在臨界微胞濃度實驗中得知，當PLLA鏈段聚合度愈低或PEG鏈段聚合度愈高，臨界微胞濃度會愈高。當親水鏈段長度增加，疏水鏈段長度相對來說減少，導致共聚物不容易形成微胞，故臨界微胞濃度提高。動態光散射實驗中可知，PLLA鏈段聚合度愈低或PEG鏈段聚合度愈高，微胞半徑愈小。微胞半徑與親疏水鏈段聚合度之間有一標度關係式，先將親水鏈段聚合度固定，可求得PLLA鏈段聚合度之標度指數，正好介於兩理想理論值之間；再將PLLA鏈段聚合度之標度指數帶回關係式中，進而求得親水鏈段聚合度之標度指數，與理想理論值比較，發現PLLA鏈段標度指數在兩理論值範圍內，而PEG鏈段標度指數不在理論值範圍內，是由於文獻中均忽略了兩團聯間的交互作用力。藥物荷載率實驗中可知，疏水鏈段聚合度愈少或親水鏈段聚合度愈高，共聚物中疏水鏈段的比例就會減少，造成藥物荷載效率及分配係數均會下降。

由上述實驗可知界面作用力在微胞態中與結晶態中均扮演著重要角色，在結晶態中實驗所求得之標度指數與理想理論值估計的相差不大，但在微胞態中實驗求得之標度指數則與理想理論值相差甚大，結晶態與微胞態中的相間界面由團聯間交互作用力所造成，但在微胞態中此作用力會受到溶劑所影響，故相對來說，其影響大於在結晶態中。

In the first part, poly (L-lactide) –poly (propylene glycol)-poly (L-lactide) (PLLA-PPG-PLLA) triblock copolymers with various PPG (degrees of polymerization from 17 to 69) and PLLA length (degrees of polymerization from 60 to 468) were synthesized. The equilibrium melting point and spherulitic growth rate of copolymers were examined with polarizing microscopy. In conjunction with data, the Hoffman nucleation theory was used to obtain kinetic parameters such as nucleation constant (Kg), pre-exponential factor (G0), and fold surface free energy (σe). The thickness of equilibrium lamellar was calculated, via equations by Hoffman-Weeks and Gibbs-Thomson-Tammann.
The equilibrium melting point decreases with the decreasing length of PLLA segments and thickening parameter decreases with the increasing length of PLLA segments. We observe the exponent (α) in power-law relationship between equilibrium lamellar thickness and degree of polymerization of PLLA, its value is more than that for the non-equilibrium lamellar thickness (with degree of supercool ranging from 30 to 90 K). The value of the exponent (α) for equilibrium lamellar thickness, determined from the experiment, is more than that as predicted from the theory. Regarding the exponent (β) in power-law relationship between equilibrium lamellar thickness and degree of polymerization of PPG, its value is less than that for the non-equilibrium lamellar thickness. The absolute value of the exponent (β) for equilibrium lamellar thickness, determined from the experiment, is less than that as predicted from the theory. This discrepancy is because that, the theory ignores the free energy of localization (floc) caused by the different flexibility between hard and soft segments, and the interfacial free energy (fint) between crystalline phase containing hard segments and amorphous one containing the soft segments.
In the second part, poly (L-lactide) –poly (ethylene glycol)-poly (L-lactide) (PLLA-PEG-PLLA) triblock copolymers with various PEG (degrees of polymerization from 23 to 91) and PLLA length (degrees of polymerization from 254 to 264) were synthesized. The critical micelle concentrations (CMC’s), micellar radius and concentration of Vitamin K3 partitioned into the micelles for various copolymers were determined with fluorescence probe method, dynamic light scattering, and UV/Vis spectroscopy, respectively.
It is found that CMC’s increase with the decreasing length of PLLA segments or increasing length of PEG segment. Because the hydrophilic segment length increases, the length of hydrophobic segments are relatively reduced, resulting copolymers are not easy to form micelle.
The micellar radius, drug loading efficiency, and partition coefficient decrease with the decreasing length of PLLA segments or increasing length of PEG segment. We observe the exponent (a) in power-law relationship between micellar radius and degree of polymerization of PLLA, its value is between two ideal theoretical values. Regarding the exponent (b) in power-law relationship between micellar radius and degree of polymerization of PEG, its value is not between two ideal theoretical values. Because ideal theoretical values assume the interaction between the two blocks is negligible.

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