本論文主要是以探究具特殊光電特性的高分子材料為主軸，依研究對象問題尺度的不同，結合多種理論原理與模擬方法，從微觀電子尺度的量子行為到原子尺度的分子動力模擬乃至牽涉介觀尺度的相變問題，建立出有效模擬模式，對系統結構特徵與物理特性之關聯性能有深入了解，期望能藉以預測各種可能行為模式，有效調節各種結構特徵，進而控制其光電特性，以提供前瞻性高分子材料設計依循之原則與方向，內文可分為三個研究主題，以共軛高分子為主軸，分別是聚對位亞苯乙烯衍生物高分子發光二極體，離子導電共軛芳香族硬桿式高分子及自組裝團聯共聚物系統。

聚對位亞苯乙烯衍生物高分子發光二極體：結合分子動力模擬和量子力學原理，發展出適用於非晶相結構的高分子系統之模擬方法，探討四種不同聚對位亞苯乙烯衍生物之分子結構堆疊特徵和發光效率與吸收光譜的關係，藉由分子動力模擬，得知這些聚對位亞苯乙烯衍生物的主鏈並非完全剛直的線行結構，由於側鏈取代基的立障效應，使主鏈呈現類螺旋狀或者鋸齒狀結構，這些彎曲的主鏈繼而堆疊成層狀結構，並利用次序參數明確的定義系統中的共軛片段分布，我們發現這些系統有一些共同特徵，共軛長度分布大約落在2到4個重複單位，這意味著電子的轉移並非沿著同一主鏈,而是藉由不同主鏈分子間相互作用傳遞。模擬結果同時顯示聚對位亞苯乙烯衍生物發光效率跟其分子堆疊有密切的關連，亦即分子鏈間具相關性的苯環面間距離在5埃附近，有利電子傳遞，這種苯環對堆疊結構數目越多，則系統放光效率愈高。模擬計算的吸收光譜與實驗光譜吻合度高，另外更由光譜的計算結果驗證分子鏈間電子傳遞的重要性。

離子導電共軛芳香族硬桿式高分子：sPBI-PS(Li+) 為一全共軛硬桿式雜環芳香族高分子，這種苯環與雜環基交替的結構，使得此硬桿式高分子具有極優越之熱穩定性與機械強度，實驗量測出經過離子混摻後，於常溫下，有極高的離子導電度10-3 S/cm，由於這個材質的熱穩定性、機械強度及導電度均優於傳統的PEO/LiX電解質材料，所以具有極高的潛力應用於高分子電解質材料。我們利用分子動力模擬探究其導電機制，發現其導電機制有別於PEO/LiX 的PEO主鏈利用扭轉角改變而造成離子傳遞之導電機制，由模擬結果清楚的顯示主鏈的排列為線型的層狀結構，並利用次序參數與扭轉角分析，發現電子的轉移無法沿著同一主鏈, 也不能藉由不同主鏈分子間作有效傳遞，所以我們相信電子無法在這個材質內作有效傳遞，這同意實驗結果主要是離子導電度。且由自由體積分析與電勢能計算更清楚的說明非等向性的離子通道，鋰離子的遷移於平行主鏈的方向較垂直主鏈的方向優越，且骨架上苯環與芳香雜環間的扭轉角變化亦不利鋰離子於垂直主鏈方向上的移動，我們發現鋰離子的轉移速率與-SO3- 的鬆弛運動有關，時間尺度在10-13 s。


自組裝團聯共聚物：利用高分子團聯共聚物的自組裝結構之特定排列與分子設計的多樣化，建立各類新穎的奈米級功能性材料，是一個積極研發的領域。我們利用分散粒子動力模擬，從分子結構特徵到系統相變行為，探討高分子團聯共聚物形成超分子至薄膜之自組裝行為與機制，瞭解不同自組裝驅動力的影響與競爭。在離子和非離子性介面活性劑的混合的水溶液系統中，我們利用分散粒子動力模擬 (DPD) 對各種不同比例調配的系統，從微胞結構，柱狀堆疊，到層狀結構，成功的模擬其各種相變行為，模擬結果各種類型的微胞尺寸和形狀與核磁共振量測結果一致，這一部分的研究我們看到了典型的相變結構與機制。第二部分是利用分子極性作用力形成特殊相結構的自組裝團聯共聚物系統，為一非對稱的蘑菇成型超分子系統，我們結合多種理論原理與模擬方法，從介觀尺度的相變問題到原子尺度的分子動力模擬乃至量子尺度的光電特性，我們做了詳盡的探討，根據 Flory-Huggins分子間作用參數會隨溫度變化，而我們研究的這三團聯共聚物由於分子內部結構特徵的特殊設計與差異，使不同分子片段與溶劑分子的作用力，隨著系統溫度的升高，出現了戲劇性的變化，也因溶劑的作用，更加強引導分子本身的極性作用，因此，由於溶劑與溫度效應，分子的自組裝行為異於一般典型相行為，形成所謂非對稱的蘑菇微胞更進而堆疊成疏水端(蘑菇頭)與親水端(蘑菇莖)相接的多層薄膜結構，也因這具極性的蘑菇薄膜，使之展現了特殊的非線性光學特性，我們成功的預測了蘑菇微胞的尺寸大小，更發現能帶間隙隨不同微胞尺寸改變，隨著微胞尺寸的增大，能隙有收斂趨勢，收斂之數值與實驗量測具一致性.

In this thesis, we investigated several photoelectric material systems consisted of conjugated polymers by means of computer simulation. We combined several theory and simulation methods to meodeling different subjects from atomic to mesoscopic scale. We dealt with the problems such as quantum efficiency, structure characteristic, and the phase behavior in material. We hope to have better understanding of the relationship between structure characteristic and functional property in material. It will help an engineering designer to adjust the variables that optimize characteristics linking the synthesis of advanced materials with desired physical properties. This work can be divided into three parts.

Long side chain substituted PPV polymers applied in light-emitting diode material : Molecular dynamics simulations were employed to investigate structure features and segment orientation of four poly(phenylene vinylene) (PPV)-like conjugated polymers with long flexible side chains at room temperature. In the simulations, the main chains of the polymers were found to be semi-rigid and to exhibit a tendency to coil into ellipsoidal helices or form zigzag conformations of only limited regularity. It was shown that continuous segments of a chain which are quasi-coplanar along the backbone are in a range of 2~4 repeat units. This implies that long-range electron transfer along same backbones of these polymers may not happen but may be mediated by interchain interactions. The ordered orientation and coupling distance of interchain aromatic rings are found to correlate with important optical properties of materials. Then we combined molecular dynamics simulation and density matrix methods modeling of amorphous light-emitting polymers. A simplified method combining molecular dynamics (MD) simulation and density matrix (DM) theory was developed for the prediction of optical properties of long side chain substituted poly(phenylene vinylene) (PPV) polymers. This MD+DM method takes account of the complexity of molecular packing of polymer chains. The method has been tested to simulate the absorption spectra of four model systems. The wavelengths of absorption maxima of the calculated spectra of these four conjugated polymers are in reasonable agreement with experimental data. The simulation also demonstrated that the importance of including interchain interactions in the calculation.

Ion-conducting polymer sPBI-PS(Li+): To understand the mechanism of ionic migration in the amorphous matrixes of polymer electrolytes is crucial for their applications in modern technologies. Here, molecular dynamics (MD) simulation was carried out to investigate the ionic conduction mechanism of a particular conjugated rigid-rod polymer, sPBI-PS(Li+). The backbone of this polymer is poly[(1, 7- dihydrobenzo[1, 2-d:4,5-d’]diimidazole- 2,6-diyl)-2-(2-sulfo)-p-phenylene]. The polymer has pendants of propane sulfonate Li+ ionomer. The MD simulations showed that the main chains of sPBI-PS(Li+) are in layer-like structure. The further detailed structure analysis suggested that the π-electron of this polymer is not delocalized among aromatic rings. This agrees with the experimental result that sPBI-PS(Li+) shows no electronic conductivity and the conductivity of this polymer is mainly ionic. The calculated migration channels of lithium ions and electrostatic potential distributions indicated clearly that the polymer matrix is anisotropic for the migrations of ions. The migration of lithium ions along the longitudinal direction is more preferable than that along the transverse direction. The relaxations of the polymer host were found to play important roles in the transfer process of lithium ions. The hopping of lithium ion from one -SO3-1 group to another is correlated strongly with characteristic motions of -SO3-1 group on a time scale of about 10-13 s.


Self-assembly functional material. Dissipative particle dynamics (DPD) simulations were carried out to investigate mixed ionic and non-ionic molecules, sodium tetradecyl sulfate (STS) and tetradecyl triethoxylated ether (C14E3) aqueous system. Different types of mixed micelles are formed depending on the concentrations of STS and C14E3. Our results are in good agreement to the early NMR measurements. From the investigation of surfactant aggregation, we understand the self-assembly mechanism and classical phase behavior in general diblock copolymer. Further, we investigated the self-assembly process on a particular mushroom-shaped supramolecular film material from molecular character to phase behavior. The miniaturized rod-coil triblock copolymers (PS-PI-RCBC) HEMME had been found to self-assemble into well-ordered nanostructures and unusual head to tail multilayer structure. The purpose of our study is to obtain fundamental understanding the connection of the inherent morphological characterization of single molecule and the mechanism of phase behavior of this polar self-assembly system. Dissipative particle dynamics simulation was carried out to study the mechanism of phase behavior of the solvent-copolymers system. We found that the solvent-induced polar effect under different temperature is important in the process of self-assembly of block copolymers. In different temperature the solvent induces hybrid structure aggregation. Our results are consistent with experimental observations and give evidence for a special mechanism governing the unusual phase behavior in thin films of modulated phases. The sizes and stabilization energies of mushroom-shaped supramolecular clusters were predicted by molecular modeling method. Clusters of sizes from 16 to 90 molecules were found to be stable. In combination of classical and simple quantum mechanical calculations, the band gaps of HEMME clusters with various sizes were estimated. The band gap was converged at 2.45 eV for cluster contains 90 molecules. Nonlinear optical properties of the material were investigated by the semi-empirical quantum mechanical calculations of molecular dipole moment and hyperpolarizabilities. Significant second-order nonlinear optical properties were shown from these calculated properties.

Chapter 1. Introduction 1
1.1 Introduction 1
1.2 Conducting Polymers 6
1.2.1 Energy Band Theory 8
1.2.2 Amorphous polymer 9
1.3 Side-chain substituted conjugated polymer 10
1.3.1 PPV-like polymer 10
1.3.2 Heterocyclic Aromatic Rigid-rod polymer 12
1.4 Block Copolymer 13
References 24

Chapter 2. Computer Simulation Methods 30
2.1 Molecular Dynamics 30
2.1.1 Verlet Leapfrog Integration 32
2.1.2 Temperature 33
2.1.3 MD Procedure 34
2.1.4 Force Field 35
2.1.5 Energy Expression 36
2.2 Dissipative Particle Dynamics 38
2.2.1 Theory and Algorithm 38
2.2.2 Dissipation and Random Noise Magnitudes 43
2.2.3 Repulsion Parameters 43
2.2.4 Mapping the Interactions onto Flory-Huggins Theory 44
2.2.5 Calculation of Flory-Huggins

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