本研究應用偏光顯微鏡 (polarized optical microscopy，POM)、廣角X光繞射儀 (wide angle X-ray diffraction，WAXD)、微分掃描熱卡計 (differential scanning calorimeter，DSC)、原子力顯微鏡 (atomic force microscopy，AFM)和掃描式電子顯微鏡 (scanning electron microscopy，SEM)分別探討：左式聚乳酸 poly(L-lactic acid) (PLLA)/右式聚乳酸 poly(D-lactic acid) (PDLA)非等莫耳混摻系統，及PLLA以溶劑揮發的方式，形成的結晶形態、晶態分析與晶板結構。
在PLLA/PDLA非等莫耳混摻系統中，藉由聚乳酸錯合物stereocomplexed-PLA (sc-PLA)之熔點較PLLA、PDLA高50 oC的特性，使用不同的熔融溫度 (Tmax)處理試樣，由POM發現在PLLA-rich系統中，不論Tmax高或低於sc-PLA之熔點皆會同時出現兩種不同的結晶形貌：輻射狀 (radiating-stripe) 球晶與小顆的結晶或負型球晶 (negative-type spherulite)，其中，輻射狀球晶是PLLA較為少見的球晶形貌。經由加熱定點觀察與WAXD分析得知，輻射狀球晶是由PLLA構成，屬於α-form的晶格。利用AFM觀察輻射狀球晶上表面，因主幹 (main stalk)與主幹間區域的晶板形狀與排列方向不同，才會造成在同一象限內同時出現不同的雙折射 (birefringence)，得以形成輻射狀的球晶形貌。
在PLLA之溶劑揮發結晶系統中，溶劑的種類、揮發速率、揮發溫度都是影響球晶形貌的重要條件。藉由改變不同的溶劑或揮發速率，可以得到截然不同的球晶形貌。當PLLA溶於四氫呋喃，在26 oC~30 oC會形成環帶狀球晶，屬於α-form的晶格。藉由SEM，環帶狀球晶上表面的晶板排列呈現樹枝狀 (dendritic)，內部則是長條狀之晶板呈放射狀，並構成層狀堆疊之結構。

Investigations on the morphology resulted from melt-crystallization of nonequimolar blends of PLLA with PDLA with regard to the prior melting temperature and crystallization temperature were conducted. When crystallized after melting at 190 oC, the PLLA/PDLA (95/5) blend exhibits large radiating-stripe spherulites surrounded by tiny spherical crystals. When crystallized after melting at 240 oC, the radiating-stripe spherulites appear with negative-type spherulites. Melting observation show that radiating-stripe spherulites belong to PLLA α-crystals, while negative-type spherulites belong to sc-PLA crystals. From the top surfaces of radiating-stripe spherulites, the lamellae are arranged at an angle of 60o with radial direction on the main stalk, while lamellae on the region between main stalks are arranged perpendicular to the main branch. Because of the difference in lamellar assembly, the blend shows different birefringence in the same quadrant, resulting in special morphology.
For neat PLLA crystallized by solvent evaporation, PLLA exhibits ring-banded morphology at 26~30 oC with tetrahydrofuran as solvent. The top surface of ring-banded spherulites shows lamellae arranged in dendritic shape. Lamellae inside spherulites arrange in radial direction, and show layer structure from lateral view.

1. X. Wang and R.E. Prud'homme, "Differences Between Stereocomplex Spherulites Obtained in Equimolar and Non-Equimolar Poly(L-lactide)/Poly(D-lactide) Blends" Macromolecular Chemistry and Physics, 212(7), p. 691-698, 2011
2. S. Jiang, C. He, L. An, X. Chen and B. Jiang, "Crystallization and Ring-Banded Spherulite Morphology of Poly(ethylene oxide)-block-Poly(ε-caprolactone) Diblock Copolymer" Macromolecular Chemistry and Physics, 205(16), p. 2229-2234, 2004
3. E.M. Woo, S. Nurkhamidah and Y.-F. Chen, "Surface and interior views on origins of two types of banded spherulites in poly(nonamethylene terephthalate)" Physical Chemistry Chemical Physics, 13(39), p. 17841-17851, 2011
4. E.M. Woo, L.-Y. Wang and S. Nurkhamidah, "Crystal Lamellae of Mutually Perpendicular Orientations by Dissecting onto Interiors of Poly(ethylene adipate) Spherulites Crystallized in Bulk Form" Macromolecules, 45(3), p. 1375-1383, 2012
5. K. Taguchi, H. Miyaji, K. Izumi, A. Hoshino, Y. Miyamoto and R. Kokawa, "Growth shape of isotactic polystyrene crystals in thin films" Polymer, 42(17), p. 7443-7447, 2001
6. K.C. Yen and E.M. Woo, "Formation of dendrite crystals in poly(ethylene oxide) interacting with bioresourceful tannin" Polymer Bulletin, 62(2), p. 225, 2008
7. X. Wang and R.E. Prud’homme, "Dendritic Crystallization of Poly(l-lactide)/poly(d-lactide) Stereocomplexes in Ultrathin Films" Macromolecules, 47(2), p. 668-676, 2014
8. L. Chang and E.M. Woo, "Effects of molten poly(3-hydroxybutyrate) on crystalline morphology in stereocomplex of poly(L-lactic acid) with poly(D-lactic acid)" Polymer, 52(1), p. 68-76, 2011
9. J. Han, G. Song and R. Guo, "Nanostructure-Based Leaf-like Polyaniline in the Presence of an Amphiphilic Triblock Copolymer" Advanced Materials, 19(19), p. 2993-2999, 2007
10. G. Lugito and E.M. Woo, "Lamellar assembly corresponding to transitions of positively to negatively birefringent spherulites in poly(ethylene adipate) with phenoxy" Colloid and Polymer Science, 291(4), p. 817-826, 2013
11. G. Lugito, C.-Y. Yang and E.M. Woo, "Phase-Separation Induced Lamellar Re-Assembly and Spherulite Optical Birefringence Reversion" Macromolecules, 47(16), p. 5624-5632, 2014
12. L.S. Nair and C.T. Laurencin, "Biodegradable polymers as biomaterials" Progress in Polymer Science, 32(8–9), p. 762-798, 2007
13. L.T. Lim, R. Auras and M. Rubino, "Processing technologies for poly(lactic acid)" Progress in Polymer Science, 33(8), p. 820-852, 2008
14. M. Vert, S.M. Li, G. Spenlehauer and P. Guerin, "Bioresorbability and biocompatibility of aliphatic polyesters" Journal of Materials Science: Materials in Medicine, 3(6), p. 432-446, 1992
15. R.E. Drumright, P.R. Gruber and D.E. Henton, "Polylactic Acid Technology" Advanced Materials, 12(23), p. 1841-1846, 2000
16. R.G. Sinclair, "The Case for Polylactic Acid as a Commodity Packaging Plastic" Journal of Macromolecular Science, Part A, 33(5), p. 585-597, 1996
17. J. Lunt, "Large-scale production, properties and commercial applications of polylactic acid polymers" Polymer Degradation and Stability, 59(1), p. 145-152, 1998
18. A.J.R. Lasprilla, G.A.R. Martinez, B.H. Lunelli, A.L. Jardini and R.M. Filho, "Poly-lactic acid synthesis for application in biomedical devices — A review" Biotechnology Advances, 30(1), p. 321-328, 2012
19. P.D. Santis and A.J. Kovacs, "Molecular conformation of poly(S‐lactic acid)" Biopolymers, 6(3), p. 299-306, 1968
20. W. Hoogsteen, A.R. Postema, A.J. Pennings, G. Brinke and P. Zugenmaier, "Crystal structure, conformation and morphology of solution-spun poly(L-lactide) fibers" Macromolecules, 23(2), p. 634-642, 1990
21. L. Cartier, T. Okihara, Y. Ikada, H. Tsuji, J. Puiggali and B. Lotz, "Epitaxial crystallization and crystalline polymorphism of polylactides" Polymer, 41(25), p. 8909-8919, 2000
22. J. Puiggali, Y. Ikada, H. Tsuji, L. Cartier, T. Okihara and B. Lotz, "The frustrated structure of poly(l-lactide)" Polymer, 41(25), p. 8921-8930, 2000
23. T. Lin, "Structure-property relationship of crystalline poly(lactic acid)s: DFT/DFPT studies and applications. " National University of Singapore, 2011.
24. B. Eling, S. Gogolewski, and A.J. Pennings, "Biodegradable materials of poly(l-lactic acid): 1. Melt-spun and solution-spun fibres" Polymer, 23(11), p. 1587-1593, 1982
25. D. Brizzolara, H.J. Cantow, K. Diederichs, E. Keller and A.J. Domb, "Mechanism of the Stereocomplex Formation between Enantiomeric Poly(lactide)s" Macromolecules, 29(1), p. 191-197, 1996
26. T. Kasuga, Y. Ota, M. Nogami and Y. Abe, "Preparation and mechanical properties of polylactic acid composites containing hydroxyapatite fibers" Biomaterials, 22(1), p. 19-23, 2000
27. D. Sawai, K. Takahashi, A. Sasashige, T. Kanamoto and S.H. Hyon, "Preparation of Oriented β-Form Poly(l-lactic acid) by Solid-State Coextrusion:  Effect of Extrusion Variables" Macromolecules, 36(10), p. 3601-3605, 2003
28. J. Zhang, Y. Duan, H. Sato, H. Tsuji, I. Noda, S. Yan and Y. Ozaki, "Crystal Modifications and Thermal Behavior of Poly(l-lactic acid) Revealed by Infrared Spectroscopy" Macromolecules, 38(19), p. 8012-8021, 2005
29. H. Marubayashi, S. Asai and M. Sumita, "Complex Crystal Formation of Poly(l-lactide) with Solvent Molecules" Macromolecules, 45(3), p. 1384-1397, 2012
30. H. Chen, M. Pyda and P. Cebe, "Non-isothermal crystallization of PET/PLA blends" Thermochimica Acta, 492(1–2), p. 61-66, 2009
31. D. Cossement, R. Gouttebaron, V. Cornet, P. Viville, M. Hecq and R. Lazzaroni, "PLA-PMMA blends: A study by XPS and ToF-SIMS" Applied Surface Science, 252(19), p. 6636-6639, 2006
32. B.M.P. Ferreira, C.A.C. Zavaglia and E.A.R. Duek, "Films of PLLA/PHBV: Thermal, morphological, and mechanical characterization" Journal of Applied Polymer Science, 86(11), p. 2898-2906, 2002
33. L. Zhao, X. Peng, X. Liu, Y. Wang, S. Qin and J. Zhang, "Miscibility and morphology of binary crystalline blends of poly(L-lactide) and poly(butylene adipate)" Polymer Journal, 45(9), p. 929-937, 2013
34. Y.-T. Hsieh, Kuo N.-T. and E.M. Woo, "Thermal analysis on phase behavior of poly(l-lactic acid) interacting with aliphatic polyesters" Journal of Thermal Analysis and Calorimetry, 107(2), p. 745-756, 2012
35. S. Nurkhamidah and E.M. Woo, "Mechanisms of Multiple Types of Lamellae and Spherulites in Poly(L‐lactic acid) Interacting with Poly(4‐vinyl phenol)" Macromolecular Chemistry and Physics, 214(20), p. 2345-2354, 2013
36. E.M. Woo, G. Lugito, J.H. Tsai and A.J. Muller, "Hierarchically Diminishing Chirality Effects on Lamellar Assembly in Spherulites Comprising Chiral Polymers" Macromolecules, 49(7), p. 2698-2708, 2016
37. Y.-T. Hsieh, S. Nurkhamidah and E.M. Woo, "Lamellar orientation and interlamellar cracks in co-crystallized poly(ethylene oxide)/poly(L-lactic acid) blend" Polymer Journal, 43(9), p. 762-769, 2011
38. J. Slager and A.J. Domb, "Biopolymer stereocomplexes" Advanced Drug Delivery Reviews, 55(4), p. 549-583, 2003
39. H. Tsuji, S. Yamamoto, A. Okumura and Y. Sugiura, "Heterostereocomplexation between Biodegradable and Optically Active Polyesters as a Versatile Preparation Method for Biodegradable Materials" Biomacromolecules, 11(1), p. 252-258, 2010
40. Y. Ikada, K. Jamshidi, H. Tsuji and S.H. Hyon, "Stereocomplex formation between enantiomeric poly(lactides)" Macromolecules, 20(4), p. 904-906, 1987
41. T. Okihara, M. Tsuji, A. Kawaguchi, K.I. Katayama, H. Tsuji, S.H. Hyon and Y. Ikada, "Crystal structure of stereocomplex of poly(L-lactide) and poly(D-lactide)" Journal of Macromolecular Science, Part B, 30(1-2), p. 119-140, 1991
42. H. Tsuji and Y. Tezuka, "Stereocomplex Formation between Enantiomeric Poly(lactic acid)s. 12. Spherulite Growth of Low-Molecular-Weight Poly(lactic acid)s from the Melt" Biomacromolecules, 5(4), p. 1181-1186, 2004
43. H. Tsuji, S.H. Hyon, and Y. Ikada, "Stereocomplex formation between enantiomeric poly(lactic acid)s. 3. Calorimetric studies on blend films cast from dilute solution" Macromolecules, 24(20), p. 5651-5656, 1991
44. H. Tsuji and Y. Ikada, "Stereocomplex formation between enantiomeric poly(lactic acid)s. IX: Stereocomplexation from the melt" Macromolecules, 26(25), p. 6918-6926, 1993
45. J. Kobayashi, T. Asahi, M. Ichiki, A. Oikawa, H. Suzuki, T. Watanabe, E. Fukada and Y. Shikinami, "Structural and optical properties of poly lactic acids" Journal of Applied Physics, 77(7), p. 2957-2973, 1995
46. H.Tsuji and Y. Ikada, "Stereocomplex formation between enantiomeric poly(lactic acid)s. XI. Mechanical properties and morphology of solution-cast films" Polymer, 40(24), p. 6699-6708, 1999
47. H. Tsuji, F. Horii, S.H. Hoyon and Y. Ikada, "Stereocomplex formation between enantiomeric poly(lactic acid)s. II, Stereocomplex formation in concentrated solutions" Macromolecules, 24(10), p. 2719-2724, 1991
48. H. Tsuji, S.H. Hyon and Y. Ikada, "Stereocomplex formation between enantiomeric poly(lactic acid)s. 4. Differential scanning calorimetric studies on precipitates from mixed solutions of poly(D-lactic acid) and poly(L-lactic acid)" Macromolecules, 24(20), p. 5657-5662, 1991
49. S. Brochu, R.E. Prud'homme, I. Barakat and R. Jerome, "Stereocomplexation and Morphology of Polylactides" Macromolecules, 28(15), p. 5230-5239, 1995
50. J. Sun, H. Yu, X. Zhuang, X. Chen and X. Jing, "Crystallization behavior of asymmetric PLLA/PDLA blends" The Journal of Physical Chemistry, Part B, 115(12), p. 2864-9, 2011
51. X. Wang and R.E. Prud'homme, "Differences Between Stereocomplex Spherulites Obtained in Equimolar and Non‐Equimolar Poly(L‐lactide)/Poly(D‐lactide) Blends" Macromolecular chemistry and physics, 212(7), p. 691-698, 2011
52. H. Tsuji and Y. Ikada, "Crystallization from the melt of poly(lactide)s with different optical purities and their blends" Macromolecular Chemistry and Physics, 197(10), p. 3483-3499, 1996
53. E.M. Woo and L. Chang, "Crystallization and morphology of stereocomplexes in nonequimolar mixtures of poly(L-lactic acid) with excess poly(D-lactic acid)" Polymer, 52(26), p. 6080-6089, 2011
54. Z. Qiu, C. Yan, J. Lu and W. Yang, "Miscible Crystalline/Crystalline Polymer Blends of Poly(vinylidene fluoride) and Poly(butylene succinate-co-butylene adipate):  Spherulitic Morphologies and Crystallization Kinetics" Macromolecules, 40(14), p. 5047-5053, 2007
55. J.P. Penning and R. St. John Manley, "Miscible Blends of Two Crystalline Polymers. 2. Crystallization Kinetics and Morphology in Blends of Poly(vinylidene fluoride) and Poly(1,4-butylene adipate)" Macromolecules, 29(1), p. 84-90, 1996
56. T. Ikehara, H. Kimura and Z. Qiu, "Penetrating Spherulitic Growth in Poly(butylene adipate-co-butylene succinate)/Poly(ethylene oxide) Blends" Macromolecules, 38(12), p. 5104-5108, 2005
57. S. Hirano, Y. Nishikawa, Y. Terada, T. Ikehara and T. Nishi, "Miscibility and crystallization behavior of crystalline/crystalline polymer blends. Poly(ester carbonate)/poly(L-lactic acid)" Polymer Journal, 34(2), p. 85-88, 2002
58. E.M. Woo and Y.H. Wang, "New Complex Crystals of Chiral Poly(L-lactic acid) and Different Tactic Poly(methyl methacrylate)" Macromolecular Chemistry and Physics, 213(16), p. 1688-1696, 2012
59. E. Gunn, R. Sours, J.B. Benedict, W. Kaminsky and B. Kahr, "Mesoscale Chiroptics of Rhythmic Precipitates" Journal of the American Chemical Society, 128(44), p. 14234-14235, 2006
60. E.M. Woo, G. Lugito and C.-E. Yang, "Analysis of crystal assembly in banded spherulites of phthalic acid upon solvent evaporation" Crystal Engineering Communication, 18(6), p. 977-985, 2016
61. H. Tsuji and S. Yamamoto, "Enhanced Stereocomplex Crystallization of Biodegradable Enantiomeric Poly(lactic acid)s by Repeated Casting" Macromolecular Materials and Engineering, 296(7), p. 583-589, 2011
62. R.H. Olley and D.C. Bassett, "An improved permanganic etchant for polyolefines" Polymer, 23(12), p. 1707-1710, 1982