【作者】 张倩；

【导师】 于晓燕；

【作者基本信息】 河北工业大学 ， 化学， 2022， 硕士

【摘要】 高分子材料的应用在给人们带来便利的同时,也带来了能源浪费与环境污染的问题。为实现可持续发展,生物可降解材料的研发得到了社会的关注。聚乙烯醇（PVA）与聚乳酸（PLA）均通过非石油路线合成,是生物相容性良好的高分子材料,具有可生物降解、透明度高、易加工等优点,然而这两种聚合物也有着类似的缺点,如热分解温度低、机械性能差、导热系数低等,一定程度上限制了聚合物的应用。因此科学研究中,通常对它们进行不同方式的改性。纳米金刚石（ND）是一种生物相容性较好的无机碳纳米材料,有着优异的杨氏模量与导热系数等参数,是性能优异的纳米增强填料,然而也因为其自身存在的较高比表面积、颗粒间的范德华力等因素,粒子团聚情况严重,继而影响复合材料的性能。本论文使用不同的试剂对纳米金刚石进行表面改性,降低其团聚情况的同时,分别制得了亲水和疏水的两种改性后粒子,扩大了纳米金刚石作为增强填料的应用范围。主要研究内容为以下两方面:（1）为了使纳米金刚石作为增强填料均匀分散在水溶性聚乙烯醇基体中,首先用聚多巴胺对纳米金刚石进行表面修饰,再通过迈克尔加成和席夫碱反应,在聚多巴胺层外部接枝聚乙烯亚胺,并探究了加入不同比例聚乙烯亚胺后,粒子接枝率的变化。通过改性,纳米金刚石在水中分散均匀,团聚情况减弱。将改性前后的粒子加入到聚乙烯醇基质中,制得一系列复合材料。结果显示,聚合物加入纳米填料后,耐热性、机械性能、导热性能均有所提高。加入改性后粒子的复合材料,各项性能得到了更有效的提升,当加入量为1.00%时,与纯PVA薄膜相比,复合薄膜导热系数为0.2544W·m^-1·K^-1,提高了148.20%;拉伸强度达到最大（73.00 MPa）,增加了113.45%。（2）为了使亲水的纳米金刚石粒子可以应用在疏水聚合物中,本文对其进行了疏水改性。将纳米金刚石粒子经聚多巴胺包覆后,利用表面的羟基引发ε-己内酯的开环反应,使其接枝在纳米金刚石表面。接枝了生物聚酯链的纳米金刚石粒子具有良好的疏水性,可以均匀分散在聚乳酸基质中。并利用改性前后的粒子,制备了一系列复合材料。结果显示,加入填料的复合材料各项性能均有所提高,尤其是改性后的粒子,当加入量为1.50%时,导热系数可达到0.6035 W·m^-1·K^-1,较纯PLA薄膜提高了159.10%,此时复合薄膜的拉伸强度达到峰值52.36 MPa,较纯PLA薄膜增加了39.63%。更多还原

【Abstract】 The application of polymer materials not only brings convenience to people,but also brings the problems of energy waste and environmental pollution.In order to achieve sustainable development,the research and development of biodegradable materials has attracted social attention.Polyvinyl alcohol（PVA）and polylactic acid（PLA）are both synthesized by non-petroleum route.They are highly biocompatible polymer materials with the advantages of biodegradation,high transparency and easy processing.However,these two polymers also have similar shortcomings,such as low thermal decomposition temperature,poor mechanical properties,low thermal conductivity,which limits the application of polymers to a certain extent.Therefore,in scientific research,they are usually modified in different ways.Nanodiamond（ND）is a kind of inorganic carbon nanomaterial with good biocompatibility,which has excellent parameters such as Young’s modulus and thermal conductivity.It is a nano reinforced filler with excellent performance.However,because of its high specific surface area and van der Waals force between particles and other factors,the agglomeration of particles is serious,which affects the properties of the composites.In this paper,different reagents were used to modify the surface of nanodiamond to reduce its agglomeration,and at the same time,hydrophilic and hydrophobic modified particles were prepared respectively,which expands the application range of nanodiamond as reinforcing filler.The main research contents are as follows:（1）In order to make nanodiamond as reinforcing filler evenly dispersed in water-soluble polyvinyl alcohol matrix.Firstly,polydopamine was used to modify the surface of nanodiamond,and then polyethyleneimine was grafted onto the surface of the polydopamine layer through Michael addition and Schiff base reaction.The change of grafting rate of particles with different proportion of polyethyleneimine was investigated.Through modification,nanodiamond is evenly dispersed in water and the agglomeration is weakened.The particles before and after modification were added into polyvinyl alcohol matrix to prepare a series of composites.The results show that the heat resistance,mechanical properties and thermal conductivity of polymer are improved by adding nano filler.When the addition amount of modified particles is 1.00%,the thermal conductivity of the composite film is 0.2544 W·m^-1·K^-1,which is 148.20%higher than that of pure PVA film.The tensile strength reached the maximum（73.00 MPa）and increased by 113.45%.（2）In order to make hydrophilic nanodiamond particles can be used in hydrophobic polymers,hydrophobic modification was carried out in this paper.After coated with polydopamine,ε-caprolactone was grafted onto the surface of nanodiamond by ring-opening reaction ofε-caprolactone initiated by hydroxyl group on the surface.The nanodiamond particles grafted with biological polyester chain have good hydrophobicity and can be evenly dispersed in polylactic acid matrix.A series of composites were prepared by using the particles before and after modification.The results show that the properties of the composites with filler are improved,especially the modified particles.When the amount of filler is 1.50%,the thermal conductivity of the composites can reach 0.6035W·m^-1·K^-1,which is 159.10%higher than that of pure PLA film.At this time,the tensile strength of the composite film reaches the peak 52.36 MPa,which is 39.63%higher than that of pure PLA film.更多还原