本研究以耗散粒子動力學模擬方法討論固定單體數目之分子鏈段聚苯乙烯-聚異戊二烯雙團聯式共聚合體(PS-b-PI)分相情形。改變鏈段PS/PI組成比例以及平衡溫度下，我們可以觀察到自組裝的現象以及最終平衡形態。初步階段，建立耗散粒子動力學模型之程式，以及將程式模擬結果與文獻比對，PS-b-PI系統，將模擬情形之比對。第二階段，將系統的平衡溫度(T=300K、350K、400K、450K、500K、550K)進行電腦模擬，結果繪製成相圖、將相圖與文獻比對。在同組成分率下設定的溫度由低到高的時候，分相的結果會循著一定的規則變化。由層板分相變為穿孔性層板，由穿孔性層板改為六角柱狀堆積，由六角柱狀堆積改為體心立方堆積，由體心立方堆積變為無序排列。

In this research we carried out studies upon phase separation of the polystyrene-polyisoprene diblock copolymers (PS-b-PI) with a fixed number of monomers via dissipative particle dynamics (DPD) simulation. When altering the fractional composition (PS/PI) of the copolymer we observed self-assembly phenomenon and equilibrium morphology of PS-b-PI. The first part of our study is the establishment of the DPD model followed by comparison of simulation results with literature. The second part is altering the simulation equilibrium temperature of system (T= 300K, 350K, 400K, 450K, 500K, 550K), deriving the resulting phase diagram and mapping the results with effective Flory-Huggins parameter chart. Our results show that when the equilibrium temperature is increased while the fractional composition remains constant, the change of equilibrium morphology follows this rule: varying from lamellar layer to perforated lamellar layer, from perforated lamellar layer to hexagonal cylinders, from hexagonal cylinders to body-centered cubic, from body-centered cubic to disorder phase.

[1] M. W. Matsen and F. S. Bates, "Unifying Weak- and Strong-Segregation Block Copolymer Theories," Macromolecules, vol. 29, pp. 1091-1098, 1996.
[2] A. K. Khandpur, et al., "Polyisoprene-Polystyrene Diblock Copolymer Phase Diagram near the Order-Disorder Transition," Macromolecules, vol. 28, pp. 8796-8806, 1995.
[3] G. Whitesides and B. Grzybowski, "Self-assembly at all scales," 2002, p. 2418.
[4] C. Park, et al., "Enabling nanotechnology with self assembled block copolymer patterns," Polymer, vol. 44, pp. 6725-6760, 2003.
[5] R. Jones, Soft condensed matter: Oxford University Press, USA, 2002.
[6] P. J. Hoogerbrugge and J. M. V. A. Koelman, "Simulating Microscopic Hydrodynamic Phenomena with Dissipative Particle Dynamics," EPL (Europhysics Letters), vol. 19, pp. 155-160, 1992.
[7] A. G. Schlijper, "Computer simulation of dilute polymer solutions with the dissipative particle dynamics method," Journal of Rheology, vol. 39, p. 567, 1995.
[8] R. D. Groot and P. B. Warren, "Dissipative particle dynamics: Bridging the gap between atomistic and mesoscopic simulation," The Journal of Chemical Physics, vol. 107, pp. 4423-4435, 1997.
[9] R. D. Groot, et al., "On the role of hydrodynamic interactions in block copolymer microphase separation," The Journal of Chemical Physics, vol. 110, pp. 9739-9749, 1999.
[10] R. Groot, "Electrostatic interactions in dissipative particle dynamics¡Xsimulation of polyelectrolytes and anionic surfactants," The Journal of Chemical Physics, vol. 118, p. 11265, 2003.
[11] J. M. Ilnytskyi, et al., "Morphological Changes in Block Copolymer Melts Due to a Variation of Intramolecular Branching. Dissipative Particles Dynamics Study," in Macromolecules vol. 41, ed: American Chemical Society, 2008, pp. 9904-9913.
[12] R. Guo, et al., "Solvent-Induced Morphology of the Binary Mixture of Diblock Copolymer in Thin Film: The Block Length and Composition Dependence of Morphology," The Journal of Physical Chemistry B, vol. 113, pp. 2712-2724, 2009.
[13] L. Leibler, "Theory of microphase separation in block copolymers," Macromolecules, vol. 13, pp. 1602-1617, 1980.
[14] S. Sakurai, et al., "Thermoreversible morphology transition between spherical and cylindrical microdomains of block copolymers," Macromolecules, vol. 26, pp. 5796-5802, 1993.
[15] C. Huang, et al., "Phase behavior of an amphiphilic molecule in the presence of two solvents by dissipative particle dynamics," Polymer, vol. 48, pp. 877-886, 2007.
[16] C.-I. Huang and H.-T. Yu, "Microphase separation and molecular conformation of AB2 miktoarm star copolymers by dissipative particle dynamics," Polymer, vol. 48, pp. 4537-4546, 2007.
[17] C. Soto-Figueroa, et al., "Self-Organization Process of Ordered Structures in Linear and Star Poly(styrene)−Poly(isoprene) Block Copolymers: Gaussian Models and Mesoscopic Parameters of Polymeric Systems," The Journal of Physical Chemistry B, vol. 111, pp. 11756-11764, 2007.
[18] L. Chang, et al., "Fast Probabilistic Ranking under x-Relation Model," 2009.
[19] P. Espanol and P. Warren, "Statistical mechanics of dissipative particle dynamics," EPL (Europhysics Letters), vol. 30, p. 191, 1995.
[20] P. Flory, "Thermodynamics of high polymer solutions," The Journal of Chemical Physics, vol. 10, p. 51, 1942.
[21] M. Huggins, "Some Properties of Solutions of Long-chain Compounds," The Journal of Physical Chemistry, vol. 46, pp. 151-158, 1942.
[22] M. Rodriguez-Hidalgo, et al., "Mesoscopic study of cylindrical phases of poly (styrene)-poly (isoprene) copolymer: Order-order phase transitions by temperature control," Polymer, vol. 50, pp. 4596-4601, 2009.
[23] C. s. Soto-Figueroa, et al., "Dissipative Particle Dynamics Study of Order−Order Phase Transition of BCC, HPC, OBDD, and LAM Structures of the Poly(styrene)−Poly(isoprene) Diblock Copolymer," Macromolecules, vol. 41, pp. 3297-3304, 2008.
[24] R. Groot and K. Rabone, "Mesoscopic simulation of cell membrane damage, morphology change and rupture by nonionic surfactants," Biophysical Journal, vol. 81, pp. 725-736, 2001.
[25] X. Li, et al., "Microphase separation of diblock copolymer poly (styrene-b-isoprene): A dissipative particle dynamics simulation study," The Journal of Chemical Physics, vol. 130, p. 074908, 2009.