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    Please use this identifier to cite or link to this item: http://ir.lib.ksu.edu.tw/handle/987654321/3421


    Title: 動態靜態光散射對PNIPAAM/water/dioxane、PNIPAAM/methanol/dioxane 溶液系統之相行為研究
    Static and Dynamic Light Scattering Study of the Phase Transition of PNIPAAM/water/dioxane、PNIPAAM/methanol/dioxane Solutions
    Authors: 陳建宏
    蘇曉慧
    邱詠迪
    林雅玲
    Keywords: 分子內練團-緻密球轉移
    分子間聚集
    PNIPAAM 三成分溶液
    intramolecular coil-to-globule transition
    intermolecular aggregation
    poly(N-isopropylacrylamide) ternary solutions
    Date: 2005-10-27
    Issue Date: 2009-08-14 23:34:01 (UTC+8)
    Abstract: 本研究為利用靜態及動態光散射來分析不同溶劑組成下PNIPAM/water/DOA 及PNIPAAM/methanol/DOA 三成份稀薄溶液中PNIPAM 分子鏈的相轉移行為變化。由靜態光散射實驗中得知在PNIPAM/water 稀薄溶液中顯示較小的A2 值(約A2 =2.27×10-5 molcm3 g-2) 及較小的Rg 值(Rg 約156 nm)。相對的在PNIPAM/DOA 稀薄溶液中顯示較大的A2 值(約A2 =2.77×10-3 mol cm3 g-2) 及較大的Rg 值(Rg 約162 nm);相似的,在PNIPAM/methanol 稀薄溶液的A2 值(約A2 =1.13×10-4 mol cm3 g-2) 及Rg 值(Rg 約185nm)。這現象意味PNIPAM 分子鏈和DOA 或methanol 之間有較大的交互作用力。由動態光散射結果得知PNIPAM/water/DOA 三成份稀薄溶液在富water 區,PNIPAM 分子鏈的水力半徑Rh 在相轉移溫度前水力半徑Rh 均突然快速上升,這現象意味PNIPAM 分子鏈間聚集形成較大之分子鏈團。當在相轉移溫度時PNIPAM 分子鏈快速的收縮而形成相轉移行為。另一方面,PNIPAAM/methanol/DOA 三成份稀薄溶液在測試中並無任何相轉移行為發生。這現象意味PNIPAM 分子鏈在不同的混合溶劑系統中的相轉移行為主要為PNIPAM 分子鏈及溶劑之間作用力所影響。因methanol 及DOA 的分子結構中均擁有親水基團與疏水基團,DOA 的分子結構中擁有二個親水基與二邊的疏水基,因此在PNIPAM/water/DOA 三成份稀薄溶液的PNIPAM 分子鏈外圍的三次元水籠結構雖然隨DOA 溶劑的混入依然可以形成,但因DOA 溶劑的體積大於水分子的體積,因此僅導致三次元水籠結構隨DOA 含量之增加而變成較不穩定,因此PNIPAM/water/DOA 三成份稀薄溶液的相轉移溫度隨DOA 含量之增加產生些微的下降。相對的, 在PNIPAAM/methanol/DOA 三成份稀薄溶液中,因不含水分子,因此在PNIPAM 分子外圍無法形成三次元水籠結構,故在任何混合溶劑比之下,PNIPAAM/methanol /DOA 三成份稀薄溶液均無任何相轉移現象產生。The relationship of cononsolvent effect on the phase transition of poly(N-isopropylacrylamide)ternary solutions (PNIPAM/water/DOA and PNIPAM/methanol/DOA dilute solutions) wasinvestigated by the static and dynamic light scattering. The result of PNIPAM aqueoussolution shows a lower A2 (the A2 is 2.27×10-5 mol cm3 g-2), and a larger Rg values ( the Rg isabout 156nm). While, the PNIPAM/DOA and PNIPAM/methanol dilute solution shows largerA2 (A2 is 2.77×10-3 and 1.13×10-4mol cm3 g-2 for PNIPAM/DOA and PNIPAM/methanol,respectively), and a lower Rg values ( the Rg is about 162 and 185nm for PNIPAM/DOA andPNIPAM/methanol, respectively). These results indicate that the interaction force betweenPNIPAAM and methanol or DOA is larger than that between PNIPAAM and water. Theresults from DLS show that, in the PNIPAM chains preferentially adsorb the water moleculerange for PNIPAM/water/DOA dilute solutions, when the temperature around the LCST, thePNIPAM molecules undergo simultaneous intermolecular aggregation or association andintramolecular coil-to-globule transition, while at temperature higher then LCST, thePNIPAM molecular only undergoes a coil-to-globule transition to form a more stable globulenanoparticle. While, in the PNIPAM/methanol/DOA dilute solutions, the intensity of DLS without any change with increasing temperature, this fact imply that the PNIPAAMmolecules without any transition occur in the PNIPAM/methanol/DOA dilute solutions.Moreover, the radius of hydrodynamic of the aggregated PNIPAM, Rhagg, evidently increaseand lead to a peak when the temperature around the LCST. This result indicates theintermolecular aggregation becomes dominate the conformation transition. While, when thetemperature at the LCST, the Rhagg shows decrease remarkable due to the intramolecularcoil-to-globule transition becomes dominate and shows the LCST transition. In contrast, theintermolecular aggregation can be completely suppressed at the PNIPAM chainspreferentially adsorb the methanol region. Therefore, the intramolecular coil-to-globuletransition slightly increases with temperature, implying leads to collapse of the PNIPAMchains into an individual globule particle. However, the phase transition of PNIPAM ternarysolutions without occurs in the PNIPAM/methanol/DOA dilute solutions at measurementrange. These results clearly indicate that the intramolecular coil-to-globule transition andintermolecular aggregation behaviors primary affection by the solvent used, i.e. that affectionby the interaction between polymer and solvents.
    Appears in Collections:[材料工程系所] 研究計畫

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