摘要
本文采用原位聚合法,在催化剂作用下,使丙交酯单体在改性的纳米二氧化硅表面开环聚合,改善了聚乳酸的性能,简化了制备工艺,直接制得聚乳酸/纳米二氧化硅复合材料。
首先以D, L-乳酸为原料,在催化剂氧化锌作用下通过脱水环化制备出了D, L-丙交酯,研究了减压脱水时间和解聚温度对丙交酯产率的影响,得出合理的制备工艺条件为:先常压脱水至液体温度为145℃,然后加入用量为1.5wt%的催化剂,在150℃下脱水反应2h;裂解温度范围为170℃~250℃,丙交酯粗产率能达到85%左右。选用无水乙醇为丙交酯重结晶溶剂,通过加热套加热,缩短了重结晶时间,并将纯丙交酯的收率提高到70%左右。经三次重结晶,丙交酯的熔程为125.2~126.3℃。
然后用硅烷偶联剂γ-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)改性纳米二氧化硅粉体,讨论了偶联剂的用量对改性效果的影响,得出了较合理的偶联剂用量为纳米二氧化硅用量的10wt%。
最后讨论了聚乳酸/纳米二氧化硅复合材料的制备方法。分析了复合材料制备过程中各种单因素(催化剂的种类和用量、反应温度、反应时间以及改性纳米二氧化硅用量)对聚合物质均分子量的影响,通过正交实验得出了最优制备工艺为:以辛酸亚锡为催化剂,其用量为丙交酯的0.25 wt%,聚合反应时间为72h,反应温度为140℃,改性纳米二氧化硅的用量为丙交酯的5wt%。按此最佳条件进行复合材料的制备,最终得到聚合物的质均分子量( M w)为1.5091×105。通过复合材料的红外光谱和扫描电镜分析,表明纳米二氧化硅与聚乳酸发生了化学结合,并且均匀的分散于聚乳酸基体中。热失重分析结果表明,随着纳米二氧化硅含量的增加,聚乳酸纳米二氧化硅复合材料的热稳定性提高。通过力学性能分析,可以看出无机纳米粒子的加入提高了材料的拉伸强度。通过材料的吸水性分析,表明纳米二氧化硅的加入明显地改善了聚乳酸的亲水性,这可以加快聚乳酸的降解速率,增强相容性。用紫外-可见光分光光度仪分析聚乳酸/纳米二氧化硅复合材料的透光性,结果表明复合材料膜的透光率与纯聚乳酸膜的透光率相当,纳米二氧化硅粒子对透光率没有影响。
In this thesis, in situ melt polymerization of D, L-lactide (DLLA) and modified nano-silica in the presence of catalyst has been proposed as a novel approach to prepare PLA/nano-silica composites. The preparation process was simplified and the properties were improved.
Firstly, D, L-lactide was prepared from D, L-lactic acid with zinc oxide as catalyst. Effects of dehydration time of lactic acid and pyrolytic temperature on crude yield of DLLA were studied. The results showed that the optimal conditions were as follows: liquid temperature was heated to 145.0℃under atmospheric dehydrated condition, then added zinc oxide amount of which was 1.5wt%, vacuum dehydration temperature was 150.0℃for 2 hours, the range of depolymerizing temperature was 170℃~250℃,crude yield of DLLA was 85%. Ethanol was used as solvent for recrystallization of DLLA. Time for recrystallization was shortened because of using heating jacket. The total yield of purified lactide increased to 70% after three recrystallizations.
Then, nano-silica was modified by coupling agentγ-glycidoxypropyl trimethoxysilane (KH-560). Influences of mass ratio of nano-SiO2/KH-560 were investigated. The optimal content of KH-560 was 10wt%.
Preparation methods of PLA/nano-silica were discussed. The influences of catalyst species and quantity, reaction temperature and time, content of nano-silica on the weight average molecular weight ( M w) of composites were discussed. The resules of orthogonal tests showed that the optimal reaction conditions were as follows:tin octoate was used as catalyst; W(SnOct2)/W(DLLA) and W(nano-SiO2)/W(DLLA) was 1:400 and 1:20, respectively; the reaction temperature was 140℃and the reaction time was 72h. Under this conditions, composites with M w of 1.5091×105 was obtained. The results of FTIR and SEM showed that nano-silica and polylactide were connected with covalent bonds, and inorganic phases were dispersed in polylactide homogeneously. The results of TG indicated that thermal decomposition temperature was increased with the increasing of silica content. The tensile strength of composites was enhanced because of adding nano-inorganic particles into polylactide. The water absorption results showed that water absorption property of PLA was improved by adding modified nano-silica which could accelerate degradation of PLA and enhance compatibility. The results of ultraviolet spectro-photometric analysis of composites indicated that light transmittance of composites was similar to that of pure PLA. The existence of nano-silica had non clear influence on the light transmittance of composites.
引文
[1]徐国富,牟申周,周灵平,等.仿生增强制备聚乳酸基骨组织工程复合材料[J].湖南大学学报:自然科学版, 2006, 33(2): 86-89.
[2]钟伟,戈进杰,马敬红,等.聚乳酸的直接缩合制备及其异氰酸酯扩链探索[J].复旦学报:自然科学版, 1999, 38(6): 705-708.
[3] DANUTA P, LIDIA S, JOLANTA S K. The Biological Assessment of Chitin Fibers[J]. Polym Medic, 2000, 30(1): 3-31.
[4] KULKARNI R K, PANI K C, NEUMAN C, et al. Poly(lactic acid) for Surgical Implants[J]. Arch. Surg, 1966, 93(8): 839-854.
[5] BRADY J M, CUTRIGHT D E. Resorption Rate, Route of Elimination and Ultrastructure of the Implant Site of Polylactic Acid in the Abdominal Wall of the Rat [J]. Journal of Biomedical Materials Research, 1973, 7(2): 155-166.
[6] YOLLES S, LEAF T, WARD L, et al. Controlled Release of Biologically Active Agents[J]. Division of Organic Coatings and Plastics Chemistry, Preprints, ACS, 1976, 36(1): 332-340.
[7] LEENSLAG J W, PENNINGS A J. Resorbable Materials of Poly(L-lactide) VI. Plates and Screws for Internal Fracture[J]. Biomaterials, 1987, 12(8): 70-75.
[8]王浩.丙交酯的合成新工艺研究[D].天津:天津大学(硕士论文), 2004: 2-18.
[9]盛敏刚,严永新,张金花,等.环境友好型生物降解材料聚乳酸的性能研究[J].中国农学通报, 2007, 23(9): 499-503.
[10]王俐.乳酸/聚乳酸生产技术进展[J].化工技术经济, 2005, 23(7): 50-56.
[11]李永振,贺继东,李阳.聚乳酸的化学合成与应用[J].化学推进剂与高分子材料, 2007, 5(5): 39-43.
[12]钱志良,胡军,吴肇祖.乳酸的工业化生产、应用和市场[J].工业微生物, 2002, 31(2): 49-53.
[13]林季,颜光涛.聚乳酸的制备及应用研究进展[J].北京生物医学工程, 2005, 24(6): 464-467.
[14]汪多仁.改性聚乳酸的开发与应用进展(1) [J].中国包装, 2007, 5(2): 21-24.
[15]李楠,姜文芳,赵京波,等. D, L-丙交酯的合成与纯化[J].石油化工, 2003,32(12): 1073-1078.
[16] BRIEN W G, CARIELLO L A, WELLS T F. Integrated Process for the Manufacture of Lactide: US Patent, 5521278[P]. 1996-05-28.
[17]娄玲,尹静波,高战团,等. L-丙交酯和聚L-乳酸的制备与性能[J].高分子材料科学与工程, 2003, 19(2): 72-75.
[18]苏涛,李曹文,黄上游.无需高真空度的D, L-丙交酯合成工艺[J].化工时刊, 1998, 12(6): 14-17.
[19]陈佳,程超,王远亮.丙交酯合成条件的研究[J].高分子材料科学与工程, 2007, 23(1): 53-55.
[20]苏涛,覃玉莹,马华,等.常压CO2气流法制D, L-丙交酯[J].精细化工, 1999, 26(3): 41-43.
[21] STERZEL H. Production of Lactide from Aqueous Lactic Acid: DE Patent, 4407036[P]. 1995-09-07.
[22] BENECKE H P, MARKLE R A, SINCLAIR R G. Catalytic Production of Lactide Directly from Lactic Acid: WO Patent, 9205168[P]. 1992-04-02.
[23] AKUTSU F, INOKI M, UEI H, et al. Synthesis of Poly(lactic acid) by Direct Polycondensation of Lactic Acid Using 1, 1′-carbonyldiimidazole, N, N, N′, N′- tetramethylchloroformamidinium Chloride, and N, N′- dicyclohexylcarbodiimide as Condensing Agent[J]. Polymer Journal, 1998, 30(5): 421-423.
[24] COSZACH P, VAN G F, BOGAERTO J C. Method for Producing Dimeric Cyclic Esters: WO Patent, 9943669[P]. 1999-09-02.
[25]苏涛,唐艳霞,刘晓静.丙交酯重结晶溶剂考察[J].科技进展, 1998, 5(12): 18-21.
[26]张贞浴,苏义华.生物降解材料聚丙交酯的研究(Ⅱ)丙交酯单体的纯化方法研究[J].黑龙江大学自然科学学报, 1998, 1(5): 110-112.
[27]李汝珍,苏涛.丙交酯中残存乳酸和水的定量测定[J].化学世界, 2000, 12(2): 105-106.
[28] AJIOKA M, ENOMOTO K, SUZUKI K, et al. Basicproperties of Polylactic Acid Produced by the Direct Condensation Polymerization of Lactic Acid[J]. Bull. Chem. Soc. Jpn, 1995, 68(8): 2125-2131.
[29] SUNG M, CHAN W L, MIYAMOTO M, et al. Melt Polycondensation of L-lactic Acid with Sn (Ⅱ) Catalysts Activated by Various Proton Acids: a Direct Manufacturing Route to High Molecular Weight Poly(L-lactic acid)[J].Journal of Polymer Science: Part A: Polymer Chemistry, 2000, 38(9): 1673-1679.
[30]王俊凤,张军,张学龙,等.聚乳酸合成的研究进展[J].化工时刊, 2007, 21(6): 51-55.
[31] KRICHELDORF H R, KREISER I. Anionic Polymerization of L-Lactide in Solution[J]. Macromol. Chem Phys, 1990, 191(5): 1057-1066.
[32] KOHN F E, OMMEN J G. The Mechanism of the Ring-opening Polymerization of Lactide and Glycolide[J]. Eur Polym J, 1983, 19(12): 1081-1088.
[33]李孝红,袁明龙,邓先模.聚乳酸及其共聚物的合成和在生物医学上的应用[J].高分子通报, 1999, 5(1): 24-32.
[34] BAZILE D, BASSOULLET M T. PEG-PLA Nanoparticles Avoid Uptake by the Mononuclear Phagolytes System[J]. Pharm Sci, 1995, 84(6): 493-495.
[35] ZHU Z X, DENG X M, XIONG C D, et al. Synthesis and Characterization of Biodegradable Block Copolymers ofε-caprolectone and D, L-lactid Initiated by Potassium Poly(ethylene glycol)[J]. Polym Sci Polym Chem, 1997, 35(6): 709-711.
[36]陈文娜,杨建,王身国,等.聚丙交酯/聚乙二醇多嵌段共聚物的合成及其性能[J].高分子学报, 2002, 23(5): 695-698.
[37]沈正荣,朱家惠,马臻. D, L-丙交酯与D, L-3-甲基-乙交酯开环共聚研究[J].功能高分子学报, 1995, 12(8): 489-493.
[38] DUBOIS P, JEROME R, TEYSSIE P. Effect of Lewis Bases on the Ring-opening Polymerization ofε-caprolectone and Lactides Initiated by Aluminum[J]. Polymer, 1994, 35(4): 23-29.
[39]朱康杰,林祥宙,杨士林,等. PEG-PLA嵌段共聚物的合成及13CNMR对平均链段长度的测定[J].高分子学报, 1988, 12(4): 358-263.
[40]李丽,于佳,刘艳红,等.聚丙交酯柠檬酸三丁酯增塑的研究[J].黑龙江自然科学学报, 2000, 17(1): 65-70.
[41]高翠丽,夏延致,纪全,等.聚乳酸的改性研究[J].材料导报, 2006, 20(6): 372-374.
[42]程俊秋,段可,翁杰,等.多孔纳米羟基磷灰石-聚乳酸复合材料的制备及其界面研究[J].化学研究与应用, 2001, 13(5): 517-520.
[43]李祖兵,胡图强,赵吉宏.混旋聚乳酸/纳米经基磷灰石板在颧上领骨骨折内固定中的应用[J].口腔医学研究, 2002, 18(5): 289-293.
[44] KASUGA T, OTA Y, NOGAMI M, et al. Preparation and Mechanical Properties of Polyactic Acid Composites Containing Hydroxyapatite Fibers[J]. Biomaterials, 2001, 22(1): 19-30.
[45] THOMSON R C, YASZEMSKI M J, POWERS J M, et al. Hydroxyapatite Fiber Reinforced Poly(A-hydroxy ester) Foams for Bone Regeneration[J]. Biomaterials, 1998, 19(21): 19-35.
[46] KASUGA T, FUJIKAWA H, ABE Y. Preparation of Polylactic Acid Composites Containingβ-Ca(PO3)2 Fibers[J]. J Mat Res, 1999, 14(2): 418-427.
[47]戴毅敏,陈新梅,毛天球,等.基因重组人骨形成蛋白-2与珊瑚/聚乳酸复合异位诱导成骨的实验研究[J].口腔医学纵横杂志, 2002, 18(1): 14-19.
[48]刘金标,陈建庭.珍珠层/聚乳酸重组人工骨的研制及其相关性能检测[J].第一军医大学学报, 2002, 22(3): 236-239.
[49]周海鸥,史铁钧,王华林,等.聚乳酸/二氧化硅有机无机杂化材料的制备和表征[J].高分子材料科学与工程, 2006, 22(2): 220-222.
[50]王玉林,齐锦刚,万怡灶,等.用于骨折内固定板的可吸收聚合物及其复合材料[J].材料工程, 1999, 12(12): 35-39.
[51]贾承德,玄秀兰,高瑞林.炭纤维织物增强聚乳酸复合材料用于预防和治疗关节的僵直和强直[J].新型炭材料, 1997, 12(2): 39-42.
[52]黄培信.组织工程学研究进展[J].中国美容医学, 2006, 15(6): 736-739.
[53] BARRERA D A, ZYLSTRA E, CANSBUEG P T, et al. Copolymerization and Degradation of Poly(lactic acid-co-lysine)[J]. Macrolmol, 1995, 28(6): 425-432.
[54]潘懋.滴定法测定气相法白炭黑比表面积的理论[J].化学世界, 1993, 45(8): 380-383.
[55]罗彦凤,王远亮,潘君,等. PLA单体-丙交酯合成方法的研究进展[J].高分子材料科学与工程, 2003, 19(1): 28-31.
[56]伍林,曹淑超,易德莲,等.六甲基二硅胺烷对纳米二氧化硅表面改性的研究[J].中国粉体技术, 2004, 10 (10): 116-118.
[57]王佼.白炭黑制备方法及表面改性研究进展[J].北京工业职业技术学院学报, 2005, 4(4): 48-54.
[58]马强,杨青芳,姚军燕.聚乳酸的合成研究[J].高分子材料科学与工程,2004, 20(3): 21-24.
[59]徐国财,张立德.纳米复合材料[M].北京:化学工业出版社, 2002: 80-83.
[60] JAMSHIDI K. Thernal Charaterization of Polylactide[J]. Polymer, 1988, 29(4): 2229-2234.
[61]全大萍,卢泽俭,李世普,等.聚D, L-丙交酯/羟基磷灰石(PDLLA/HA)复合材料(I):制备及力学性能[J].中国生物医学工程学报, 2001, 6(20): 483-488.
[62]孙水升,李春忠,张玲,等.纳米二氧化硅颗粒表面设计及其填充聚氯乙烯复合材料的性能[J].高校化学工程学报, 2006, 20(5): 801-803.