【作者】 王璐；

【导师】 张风华；

【作者基本信息】 哈尔滨工业大学 ， 材料与化工（专业学位）， 2022， 硕士

【摘要】 形状记忆聚合物是一种智能材料,能够感知热、磁、电、光等外部刺激并做出响应从临时形状回复至原始形状。形状记忆聚合物具有质轻、变形量大等优点,目前已广泛应用于航空航天、智能制造、柔性电子、生物医学等领域。随着各研究领域对精密制造及小尺寸器件的需求增大,形状记忆聚合物等智能变形材料也向着微纳米尺寸发展。微纳米纤维具有高比表面积和孔隙率等优点,适用于生物医学领域。因此,本论文设计并制备了形状记忆聚合物复合材料,采用静电纺丝技术制备了形状记忆微纳米纤维,研究了纺丝参数对纤维结构及形貌的影响,并通过扫描电子显微镜、拉伸、水接触角、BET比表面积等表征手段系统研究了形状记忆聚合物微纳米纤维膜的微观结构、热力学、形状记忆等性能,实现了形状记忆纤维膜在药物释放和青光眼术后抗瘢痕化方面的功能验证。主要研究内容如下:针对形状记忆聚乳酸(PLA)的变形温度高、韧性差等问题,通过引入生物可降解的聚对二氧己酮(PPDO),调控复合材料的热学、力学、形状记忆等性能。进一步通过在该复合材料中加入增塑剂柠檬酸三丁酯(TBC)来实现降低转变温度和增韧的作用,获得PLA9/PPDO1+40%TBC复合材料体系的转变温度为41.3℃,且具有良好的形状记忆性能,形状回复率能够达到100%。通过活/死染色和H&E染色生物学验证,该材料具有较好的细胞增殖效果,满足生物医学应用要求。针对静电纺丝纤维膜与天然细胞外基质具有相似三维结构,利用静电纺丝技术,将上述获得的PLA9/PPDO1+40%TBC复合材料制备成微纳米纤维,研究了纺丝液浓度和环境湿度对纤维微观结构、形貌及纤维直径与分布的影响。由于纺丝过程中的表面屈曲不稳定性和溶液中PLA/PPDO/TBC的相分离及固化,纤维表面具有褶皱形貌,当纺丝液浓度为22wt%时,褶皱最明显。该纤维具有较好的韧性,其断裂伸长率可达89.3%,同时具有良好的形状记忆性能,响应速度快。此外,通过宏观拉伸和形状记忆效应能够使纤维的表面形貌在褶皱和光滑之间转换。通过将纺丝液与药物溶液混溶经静电纺丝制备形状记忆PLA/PPDO载药纤维膜。分别研究了载药量和形变对载丝裂霉素(MMC)/盐酸阿霉素(DOX)纤维膜的药物释放行为的影响。对于同种药物,载药量越大,药物释放速率越快,药物累积释放量越大;且拉伸变形后的载药纤维膜的药物释放速率要快于原始形状。为模拟眼部应用环境,采用微量输液泵法对MMC纤维膜进行药物释放实验,结果与上述结论一致。此外,进一步验证了未载药/载药纤维膜的抗瘢痕化作用,该微纳米纤维膜本身即具有良好的抗瘢痕效果,载药后效果更佳,还验证了拉伸变形对瘢痕的影响。该纤维膜在实现药物智能控释的同时还具有明显的抗瘢痕化作用。更多还原

【Abstract】 Shape memory polymers are smart materials that can sense external stimuli such as heat,magnetism,electricity,light,etc.and respond from temporary shape to original shape.Shape memory polymers have the advantages of light weight and large deformation,and have been widely used in aerospace,smart manufacturing,flexible electronics,biomedicine and other fields.With the increasing demand for precision manufacturing and small-scale devices in various research fields,smart deformable materials such as shape memory polymers are also developing towards micro-and nanoscale.Micro-nanofibers have the advantages of high specific surface area and porosity,and are suitable for the biomedical field.Therefore,in this paper,shape memory polymer composites were designed and prepared,and shape memory micro-nano fibers were prepared by electrospinning technology.The effects of spinning parameters on fiber structure and morphology were studied.The microstructure,thermodynamics,shape memory and other properties of shape memory polymer micro-nanofiber membranes were systematically studied by means of characterization methods such as water contact angle,BET specific surface area,etc.functional verification.The main research contents are as follows:Aiming at the problems of high deformation temperature and poor toughness of shape memory polylactic acid(PLA),the thermal,mechanical,shape memory and other properties of the composite were regulated by introducing biodegradable poly-pdioxanone(PPDO).Further,the plasticizer tributyl citrate(TBC)was added to the composite to achieve the effect of reducing the transition temperature and toughening,and the transition temperature of the PLA9/PPDO1+40%TBC composite system was41.3°C,and it has Good shape memory performance,the shape recovery rate can reach100%.Biologically verified by live/dead staining and H&E staining,the material has good cell proliferation effect and meets the requirements of biomedical applications.Aiming at the similar three-dimensional structure of electrospinning fiber membrane and natural extracellular matrix,the PLA9/PPDO1+40%TBC composite material obtained above was prepared into micro-nanofibers by electrospinning technology,and the concentration of spinning solution and environmental humidity were studied.Effects on fiber microstructure,morphology,and fiber diameter and distribution.Due to the surface buckling instability during spinning and the phase separation and solidification of PLA/PPDO/TBC in solution,the fiber surface has a wrinkled morphology,and the wrinkling is most obvious when the spinning solution concentration is 22 wt%.The fiber has good toughness,its elongation at break can reach 89.3%,and it has good shape memory performance and fast response speed.Furthermore,the surface topography of the fibers can be switched between wrinkled and smooth through macroscopic stretching and shape memory effects.Shape memory PLA/PPDO drug-loaded fibrous membranes were prepared by mixing spinning solution with drug solution.The effects of drug loading and deformation on the drug release behavior of mitomycin-loaded(MMC)/doxorubicin hydrochloride(DOX)fibrous membranes were investigated,respectively.For the same drug,the larger the drug loading,the faster the drug release rate and the greater the cumulative drug release amount;and the drug release rate of the drug-loaded fiber film after tensile deformation is faster than the original shape.In order to simulate the ocular application environment,the microinfusion pump method was used to conduct drug release experiments on MMC fiber membranes,and the results were consistent with the above conclusions.In addition,the anti-scarring effect of the unloaded/drug-loaded fibrous membrane was further verified.The micro-nano fibrous membrane itself has a good antiscar effect,and the effect is better after drug loading.The effect of tensile deformation on scar is also verified.The fibrous membrane has obvious anti-scarring effect while realizing the smart controlled release of the drug.更多还原