摘要
近年来,双亲性共聚物的自组装及其应用研究备受学术及工业界关注,嵌段共聚物自组装研究较为广泛,但因其合成复杂,不易大规模生产。相比较而言,无规、交替共聚物合成简单,具有潜在的应用前景,但相关研究报告较嵌段共聚物而言较少。将双亲无规-交替共聚物自组装胶束作为固体颗粒乳化剂的研究则几乎未见报道,无规及交替共聚物胶束不像嵌段共聚物胶束那样具有明显的核壳结构,由于其特殊的链结构致使胶束表面富集亲水基元和部分疏水基元,具有双亲性,因此有较好的乳化性能,可作为颗粒乳化剂。用聚合物自组装胶束作为乳化剂制得的水包油乳液滴可作为油溶性活性物的“微容器”。
本文制备了光敏无规双亲性共聚物及交替双亲性共聚物,研究了这两种聚合物的自组装行为;尝试以自组装胶束为颗粒乳化剂,探索了胶束颗粒乳化剂的乳化性能及其对油溶性染料的乳化、包覆性能,拓展了聚合物自组装胶束研究的新领域;另尝试将共聚物与染料共同自组装,初步研究了交替共聚物上脂肪链存在与否对其胶束包覆染料性能的影响。采用无规双亲性共聚物自组装胶束以乳化的方式将油性物包覆于乳液滴内的研究鲜见报道,本文的主要工作如下:
1、以苯乙烯类光敏单体7-(4-乙烯基苄氧基)-4-甲基香豆素(VM)、苯乙烯(St)、马来酸酐(MA)为共聚单体,采用自由基聚合法制备了光敏无规双亲性共聚物P(St/VM-co-MA)。利用傅立叶变换红外光谱(FT-IR)、~1H核磁共振(~1H-NMR)、凝胶渗透色谱(GPC)、差示扫描量热仪(DSC)等手段对所得聚合物结构进行表征。在选择性溶剂(N,N-二甲基甲酰胺(DMF)/H_2O)中对P(St/VM-co-MA)进行自组装,用透射电镜(TEM)和动态激光光散射(DLS)表征了自组装胶束的形态、粒径大小及其分布。利用紫外光照使胶束中香豆素基团发生光二聚反应,形成交联胶束。用紫外-可见光分光光度计(UV-Vis)、荧光分光光度计、DLS研究了pH、盐浓度等对胶束的光敏性、荧光性及结构稳定性的影响。结果表明:胶束的光响应性随pH增大而加快,随盐浓度增大而减慢;在pH 1-12范围内,未经交联胶束的荧光强度高于交联胶束,且两者荧光强度均在pH为中性时达到最大;胶束结构稳定性因光照交联而提高。
2、以P(St/VM-co-MA)胶束为固体颗粒乳化剂,溶剂黄98染料溶液为油相,经高速乳化分散可得到系列O/W型乳状液,研究了胶束浓度、油水体积比、光照交联、pH、盐浓度、油相固化等因素对胶束乳化、包覆性能的影响。结果表明:当胶束浓度大于2 mg/L,油水比小于2:1时,可制得稳定的乳状液;未经交联和交联胶束在乳化过程中均可实现对油溶性染料的包覆;以交联胶束为乳化剂时,扩大了乳状液包覆染料所适用的pH、盐浓度范围;以含有引发剂的苯乙烯-染料为油相,聚合可得到固化乳状液,对染料的包覆可靠性提高,这也是本文的创新点之一。
3、利用P(St-alt-MA)中酸酐基元与脂肪胺的胺解反应,制备了拥有柔性链的交替双亲性共聚物P(St-alt-MAA_8)。用FT-IR、~1H-NMR、GPC对其结构进行表征,用UV-Vis、TEM、纳米粒度及Zeta电位分析仪(ZS)等技术研究了聚合物在选择性溶剂中的自组装行为。采用聚合物与染料共同自组装的方法得到了P(St-alt-MA)/dye及P(St-alt-MAA_8)/dye复合物胶束。结果表明:聚合物浓度、自组装方法、pH、盐浓度等对聚合物胶束粒径影响较大,而超声处理对胶束粒径及其分布基本无影响;复合物胶束较聚合物胶束粒径小,且当共聚物上引入脂肪长链时,可使其胶束包覆染料性能提高。
During recent years, self-assembly and applied studies of amphiphilic copolymers have attracted greater attention from academia and industry member. So far most studies on self-assembly have focus on block copolymers. Because of their complex synthesis, it is different to mass produce. Compared to block copolymers, random and alternating copolymers are much easy to synthesis, so they have potential applicable prospects. Additionally, random and alternating copolymers self-assemble micelles can be used as particulate emulsifier, but corresponding research reports are few. Block copolymers self-assemble into core-shell structure, while the surface of random copolymer micelles are enriched hydrophilic segment and partial hydrophobic segment, so the micelles have amphiphilicity and can be used as emulsifier. The oil phase of O/W emulsion could be took as microencapsulate of oil-soluble actives.
In this paper, photosensitive random amphiphilic copolymer and alternating amphiphilic copolymer were synthesized respectively. Their self-assemble behavior were studied. We attempt to use self-assemble micelles as particular emulsifier to study their emulsification and encapsulation, wish to expand the research domain of copolymer micelles. Additionally, we try to research the effect of aliphatic chains in the alternating copolymer which simultaneous self-assemble with dye on their micellar encapsulation. The actives could be encapsulated into emulsions which were stabilized by random copolymer micelles. To the best of our knowledge, no attempt has been reported so far. My paper divides three parts.
1. A photosensitive random copolymer P(St/VM-co-MA) was synthesized from styrene (St), a styrene-containing photosensitive monomer 7-(4-vinylbenzyloxy)-4-methyl coumarin (VM) and maleic anhydride (MA) by free radical copolymerization. Its structure was characterized by FT-IR, ~1H-NMR, GPC and DSC. P(St/VM-co-MA) self-assembled into micelles in the selective solvent DMF/H_2O. The morphologies, sizes, and size distributions of the micelles were characterized by TEM and DLS. The micelles were photo-crosslinked by the photodimerization of the coumarin groups under UV irradiation to form crosslinked micelles. The photosensitivity, fluorescence and structural stability of micelles were studied by UV-Vis, fluorospectro photometer and DLS. The results showed that micellar photosensitivity increased with increasing pH, and decreased with increasing salt concentration. The fluorescence intensity of non-crosslinked micelles was higher than those of crosslinked in pH 1-12 scope, and the intensity reached maximum when pH was neutral. The micellar structure was strengthened when it was photo-crosslinked.
2. The O/W emulsion was prepared by homogenizing with Solvent Yellow 98 dye solution as oil phase, and P(St/VM-co-MA) micelle as particulate emulsifier. The effects of micellar concentration, oil/water ratio, photo-crosslinked, pH, salt concentration and oil solidified on emulsification and encapsulation were studied. Results showed that when micellar concentration was bigger than 2 mg/mL and oil/water ratio less than 2:1, the micelles could stabilize emulsion. During emulsification, the oil-soluble dye was encapsulated into emulsion. When use the crosslinked micelles as emulsifier, they could expand the range pH, salt concentration of micelles stabilized emulsion and the emulsification and encapsulation were both improved. Solidified droplets were obtained by polymerizing the oil phase of styrene-dye containing the initiator AIBN to enhance encapsulation, which is an innovation of this paper.
3. A alternating copolymer P(St-alt-MAA_8) with long anhydride chains was obtained by aminolysis between maleic group of P(St-alt-MA) and aliphatic amine. Its structure was characterized by FT-IR, ~1H-NMR and GPC. The self-assembly behavior of P(St-alt-MAA_8) was studied by UV-Vis, TEM and ZS. P(St-alt-MA)/dye and P(St-alt-MAA_8)/dye complex micelles were obtained by simultaneous self-assembly of dye and copolymer. The results indicated that copolymer concentration, self-assemble methods, pH, salt concentration influenced the micellar sizes greatly, while ultrasonic treatment was less influential. The complex micelles sizes were smaller than those of polymeric micelles. When the alternating copolymer has anhydride chains, their encapsulation could be improved.
引文
1. Zhang L F, Eisenberg A. Multiple morphologies and characteristics of crew-cut micelle-like aggregates of polystyrene-b-poly(acrylic acid) diblock copolymers in solution [J].Science, 1995, 268(5218):1728-1731
2. Zhang L F, Eisenberg A. Formation of crew-cut aggregates of various morphologies from amphiphilic block copolymers in solution [J]. Polymer Advance Technology, 1998, 9(10-11): 677-699
3. Zhang L F, Eisenberg A. Multiple morphologies and characteristics of“crew-cut”micelle-like aggregates of polystyrene-b-poly(acrylic acid) diblock copolymers in aqueous solutions [J]. Journal of the American Chemical Society, 1996, 118(13): 3168-3181
4. Shen H, Eisenberg A. Block length dependence of morphological phase diagrams of the ternary system of PS-b-PAA/dioxane/H_2O [J]. Macromolecules, 2000, 33(7):2561-2572
5. Yu K, Eisenberg A. Multiple morphologies in aqueous solutions of aggregates of polystyrene-block-poly(ethylene oxide) diblock copolymers [J]. Macromolecules, 1996, 29(19):6359-6361
6. Yu K, Eisenberg A. Bilayer morphologies of self-assembled crew-cut aggregates of amphiphilic PS-b-PEO diblock copolymers in solution [J]. Macromolecules, 1998, 31(11): 3509-3518
7. Liu X Y, Kim J S, Wu J, et al. Bowl-shaped aggregates from the self-assembly of an amphiphilic random copolymer of poly(styrene-co-methacrylic acid) [J]. Macromolecules, 2005, 38(16): 6749-6751
8.江明,艾森伯格A,刘国军等.大分子自组装[M].北京:科学出版社, 2006. 311-312
9. Liu S Y, Zhu H, Zhao H, Jiang M, et al. Interpolymer hydrogen-bonding complexation induced micellization from polystyrene-b-poly(methyl methacrylate) and PS(OH) in toluene [J]. Langmuir, 2000, 16(8): 3712-3717
10. Wang M, Jiang M, Ning F, et al. Block-copolymer-free strategy for preparing micelles and hollow spheres: self-assembly of poly(4-vinylpyridine) and modified polystyrene [J]. Macromolecules, 2002, 35(15): 5980-5989
11. Chen D Y, Jiang M. Strategies for constructing polymeric micelles and hollow spheres in solution via specific interaction [J]. Accounts of Chemical Research 2005, 38(6): 494-502
12. Martin T J, Prochazka K, Webber S E, et al. pH-dependent micellization of poly(2-vinylpyridine)-block-poly(ethylene oxide) [J]. Macromolecules, 1996, 29(18) 6071-6073
13. Topp M D C, Dijkstra P J, Talsma H, et al. Thermosensitive micelle-forming block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) [J]. Macromolecules, 1997, 30(26): 8518-8520
14. Forder C, Patrickios C S, Armes S P, et al. Synthesis and Aqueous solution characterization of dihydrophilic block copolymers of methyl vinyl ether and methyl triethylene glycol vinyl ether[J]. Macromolecules, 1996, 29(25): 8160-8169
15. Hui T D, Chen D Y, Jiang M, et al. A one-step approach to the highly efficient preparationof core-stabilized polymeric micelles with a mixed shell formed by two incompatible polymers [J]. Macromolecules, 2005, 38(13): 5834-5837
16. Bronich T K, Keifer P A, Shlyakhtenko L S, et al. Polymer micelle with cross-linked ionic core [J]. Journal of the American Chemical Society, 2005, 127(23): 8236-8237
17. Schmidt V, Borsali R, Giacomelli C. Aggregation of a versatile triblock copolymer into pH-responsive cross-linkable nanostructures in both organic and aqueous media [J]. Langmuir, 2009, 25(23): 13361-13367
18. Jiang X Z, Liu S Y, Narain R. Degradable thermoresponsive core cross-linked micelles: fabrication, surface functionalization, and biorecognition [J]. Langmuir, 2009, 25(23):13344-13350
19. Wooley K L.Shell crosslinked polymer assemblies: nanoscale constructs inspired from biological systems [J]. Journal of Polymer Science Part A: Polymer Chemistry, 2000, 38(9):1397-1407
20. Zhang Y W, Jiang M, Zhao J X, et al. Hollow spheres from shell cross-linked, noncovalently connected micelles of carboxyl-terminated polybutadiene and poly(vinyl alcohol) in water [J]. Macromolecules, 2004, 37(4): 1537-1543
21. Zhang Y W, Jiang M, Zhao J X, et al. pH-Responsive core-shell particles and hollow spheres attained by macromolecular self-assembly [J]. Langmuir, 2005, 21(4): 1531-1538
22. Pickering S U J. Chemical Society, 1907, 91: 2001
23. Aveyard R, Binks B P, Clint J H. Emulsions stabilised solely by colloidal particles [J]. Advances in Colloid and Interface Science, 2003, 100-102: 503-546
24. Binks B P, Murakami R, Armes S P, et al. Temperature-induced inversion of nanoparticle-stabilized emulsions [J]. Angewandte Chemie International Edition, 2005, 44 (30):4795-4798
25. Fujii S, Cai Y L, Weaver J V M, et al. Syntheses of shell cross-linked micelles using acidic ABC triblock copolymers and their application as pH-responsive particulate emulsifiers [J]. Journal of the American Chemical Society, 2005, 127(20): 7304-7305
26. Li Z F, Ngai T. Macroporous polymer from core-shell particle-stabilized Pickering emulsions [J]. Langmuir, 2010, 26(7):5088-5092
27. Schatz C, Smith E G, Armes S P, et al. Reversible pH-triggered encapsulation and release of Pyrene by adsorbed block copolymer micelles [J]. Langmuir, 2008, 24(15): 8325-8331
28. Choucair A, Eisenberg A. Interfacial solubilization of model amphiphilic molecules in block copolymer micelles [J]. Journal of the American Chemical Society, 2003, 125(39): 11993-12000
29. Soo P L, Sidorov S N, Mui J, et al. Gold-labeled block copolymer micelles reveal gold aggregates at multiple subcellular sites [J]. Langmuir, 2007, 23(9): 4830-4836
30. Vyhnalkova R, Eisenberg A, van de Ven T G M, et al. Loading and release mechanisms of a biocide in polystyrene-block-poly(acrylic acid) block copolymer micelles [J]. The Journal of Physical Chemistry B, 2008, 112(29): 8477-8485
31. Giacomelli C, Schmidt V, BorsaliR, et al. Specific interactions improve the loading capacity of block copolymer micelles in aqueous media [J]. Langmuir, 2007, 23(13): 6947-6955
32. Savic R, Luo L B, Eisenberg A, et al. Micellar nanocontainers distribute to defined cytoplasmic organelles [J]. Science, 2003, 300(5619): 615-618
33. Velev O D, Furusawa K, Nagayama K. Assembly of latex particles by using emulsion droplets as templates. 2. ball-like and composite aggregates [J]. Langmuir, 1996, 12(10): 2385-2391
34. Velev O D, Furusawa K, Nagayama K. Assembly of latex particles by using emulsion droplets as templates. 1. microstructured hollow spheres [J]. Langmuir, 1996, 12(10): 2374-2384
35. Hsu M F, Nikolaides M G, Dinsmore A D, et al. Self-assembled shells composed of colloidal particles: fabrication and characterization [J]. Langmuir, 2005, 21(7): 2963-2970
36. Dinsmore A D, Hsu M F, Nikolaides M G, et al. Colloidosomes: selectively permeable capsules composed of colloidal particles [J]. Science, 2002, 298(5595): 1006-1009
37. Wu C Y, Tarimala S, Dai L L. Dynamics of charged microparticles at oil-water interfaces. Langmuir, 2006, 22(5): 2112-2116
38. Yow H N, Routh A F. Release profiles of encapsulated actives from colloidosomes sintered for various durations [J]. Langmuir, 2008, 25(1): 159-166
39. Mak W C, Bai J H, Chang X Y, et al. Matrix-assisted colloidosome reverse-phase layer-by-layer encapsulating biomolecules in hydrogel microcapsules with extremely high efficiency and retention stability [J]. Langmuir, 2008, 25(2): 769-775
40. Addison T, Cayre O J, Biggs S, et al. Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles [J]. Langmuir, 2010, 26(9): 6281-6286
41. Ao Z, Yang Z, Wang J F, et al. Emulsion-templated liquid core-polymer shell microcapsule formation [J]. Langmuir, 2009, 25(5): 2572-2574
42. Mazur M. Polypyrrole containers grown on oil microdroplets: encapsulation of fluorescent dyes [J]. Langmuir, 2008, 24(18): 10414-10420
43. Mazur M. Preparation of surface-supported polypyrrole capsules using a solidified droplets template approach [J]. The Journal of Physical Chemistry B, 2008, 113(3): 728-733
44. Bae K H, Lee Y H, Park T G. Oil-encapsulating PEO-PPO-EO/PEG shell cross-linked nanocapsules for target-specific delivery of paclitaxel [J]. Biomacromolecules, 2007, 8(2): 650-656
45. Noble P F, Cayre O J, Alargova R G, et al. Fabrication of“hairy”colloidosomes with shells of polymeric microrods [J]. Journal of the American Chemical Society, 2004, 126(26): 8092-8093
46. Zhu H, McShane M J. Loading of hydrophobic materials into polymer particles: implications for fluorescent nanosensors and drug delivery [J]. Journal of the American Chemical Society, 2005, 127(39): 13448-13449
47. Kim J, Hong D, Chung Y. et al. Ammonolysis-induced solvent removal: a facile approach for solidifying emulsion droplets into PLGA microspheres [J]. Biomacromolecules, 2007, 8(12): 3900-3907
48. Gindy M E, Panagiotopoulos A Z, Prud'homme R K, et al. Composite block copolymer stabilized nanoparticles: simultaneous encapsulation of organic actives and inorganicnanostructures [J]. Langmuir, 2007, 24(1): 83-90
49. Kitajyo Y, Imai T, Sakai Y, et al. Encapsulation-release property of amphiphilic hyperbranched d-glucan as a unimolecular reverse micelle [J]. Polymer, 2007, 48(5): 1237-1244
50. Wan D C, Yuan J J, Pu H T. Macromolecular nanocapsule derived from hyperbranched polyethylenimine (HPEI): mechanism of guest encapsulation versus molecular parameters [J]. Macromolecules, 2009, 42(5): 1533-1540
51. Liu C H, Gao C, Yan D Y. Synergistic supramolecular encapsulation of amphiphilic hyperbranched polymer to dyes [J]. Macromolecules, 2006, 39(23): 8102-8111
52. Irfan M, Seiler M. Encapsulation using hyperbranched polymers: from research and technologies to emerging applications [J]. Industrial & Engineering Chemistry Research, 2010, 49(3): 1169-1196
53. Zhao Y, Bertrand J, Tong X. Photo-cross-linkable polymer micelles in hydrogen-bonding-built layer-by-layer films [J]. Langmuir, 2009, 25(22): 13151-13157
54. He J, Tong X, Zhao Y. Photoresponsive nanogels based on photocontrollable cross-links [J]. Macromolecules, 2009, 42(13): 4845-4852
55. Jiang J Q, Tong X, Zhao Y. A new design for light-breakable polymer micelles [J]. Journal of the American Chemical Society, 2005, 127(23): 8290-8291
56. Jiang J Q, Tong X, Morris D. Toward photocontrolled release using light-dissociable block copolymer micelles [J]. Macromolecules, 2006, 39(13): 4633-4640
57.杨金会,计从斌,赵艳敏.一水硫酸氢钠无溶剂催化合成4-甲基香豆素[J].有机化学, 2008, 28(10): 1740-1743
58.傅祺.超支化聚酯的合成与表面修饰及其光敏性能研究[D]:[博士学位论文]合肥:中国科学技术大学, 2009
59. Malardier-Jugroot C, van de Ven T G M. Linear conformation of poly(styrene-alt-maleic anhydride) capable of self-assembly: a result of chain stiffening by internal hydrogen bonds [J]. The Journal of Physical Chemistry B, 2005, 109(15): 7022-7032
60. Trenor S R, Shultz A R, Love B J, et al. Coumarins in polymers: from light harvesting to photo-cross-linkable tissue scaffolds [J]. Chemical Reviews, 2004, 104(6): 3059-3077
61.江金强,冯艳,王红梅等.光敏感双亲性梳状SMA聚合物的合成及其胶束化[J].物理化学学报, 2008, 24(11): 2089-2095
62. Ren B, Zhao D L, Liu S S, et al. Synthesis and characterization of poly(ferrocenylsilanes) with coumarin side groups and their photochemical reactivity and electrochemical behavior [J]. Macromolecules, 2007, 40(13): 4501-4508
63. Li Y B, Deng Y H, Tong X L, et al. Formation of photoresponsive uniform colloidal spheres from an amphiphilic azobenzene-containing random copolymer [J]. Macromolecules, 2006, 39(3): 1108-1115
64. Choudhury S D, Pal H. Modulation of excited-state proton-transfer reactions of 7-Hydroxy-4-methylcoumarin in ionic and nonionic reverse micelles [J]. The Journal of Physical Chemistry B, 2009, 113(19): 6736-6744
65.董社英,李靖,黄延林.新型4-羟基香豆素衍生物的微波合成及其光谱性质[J].高等学校化学学报, 2009, 30(8): 1516-1521
66. Ma Y C, Farinha J P S, Winnik M A. Compatibility of chlorinated polyolefin with the components of thermoplastic polyolefin: a study by laser scanning confocal fluorescence microscopy [J]. Macromolecules, 2004, 37(17): 6544-6552
67. Binks B P, Murakami R, Armes S P, et al. Effects of pH and salt concentration on oil-in-water emulsions stabilized solely by nanocomposite microgel particles [J]. Langmuir, 2006, 22(5): 2050-2057
68.周芬,杨子刚,翟超等.嵌段共聚物PLL-PEG-PLL/DNA复合物胶束[J].化学与生物工程, 2004,(5): 26-28
69.杨子刚,周芬,袁建军等. PLL-PEG-PLL三嵌段共聚物的制备及DNA包覆应用[J].中国科学B辑化学, 2005, 35(6): 492-498
70.任现文,江明.原位聚合法制备温敏性聚合物核壳胶束的响应温度调控及其负载行为[J].高等学校化学学报, 2006, 27(11): 2204-2208
71. Garnier G, Duskova-Smrckova M, Vyhnalkova R, et al. Association in solution and adsorption at an air-water interface of alternating copolymers of maleic anhydride and styrene [J]. Langmuir, 2000, 16(8): 3757-3763
72. Suslick K S. Sonochemistry [J]. Science, 1990, 247(4949): 1439-1445
73. Wang J, Pelletier M, Zhang H J, et al. High-frequency ultrasound-responsive block copolymer micelle [J]. Langmuir, 2009, 25(22): 13201-13205
