【作者】 仇德朋；

【导师】 侯万国；

【作者基本信息】 山东大学 ， 物理化学， 2009， 博士

【摘要】 我国是世界上第二大农药生产国,但与发达国家相比,长期存在剂型结构不合理,制剂质量差等问题。目前我国的农药制剂仍以传统的粉剂、乳油和悬浮剂为主,技术落后,药效差,且对环境污染严重。近年来,以安全、经济、环保为目标的农药新剂型研制日益受到重视,其中农药控释剂型已成农药剂型领域的研究热点。类水滑石（Hydrotalcite-like compounds,简称HTlc）是由两种或两种以上金属元素组成的具有水滑石层状晶体结构的氢氧化物,层片带结构正电荷,层间存在可交换的阴离子。HTlc层间可作为微型储存器,将农药分子插入其中制成农药-HTlc纳米杂化物,因空间位阻效应和农药分子与层板间的相互作用可实现对农药分子的控释。近期,农药-HTlc纳米杂化物的制备及在农药控释剂型中的应用备受关注。本文分别选取阴离子型水溶性农药吲哚丁酸（Indole-3-bytric acid,简称IBA）、非离子型水溶性农药吡虫啉（Imidacloprid,简称IM）和非离子型水难溶性农药阿维菌素（Avermectin,简称AVM）为客体分子,以HTlc为主体,分别采用离子交换法、二次组装法和二次组装蒸发溶剂促进插层法制备了三种农药/HTlc纳米杂化物,考察了其释放行为,探讨了释放机理。以期掌握农药-HTlc纳米杂化物的关键制备技术,了解其农药控释规律,为进一步的实际应用奠定基础。本文研究的主要内容和结论归纳如下。1、吲哚丁酸-Mg₂Al HTlc纳米杂化物的制备及其缓释性能研究（1）研究了阴离子型水溶性农药吲哚丁酸（IBA）在Mg₂Al类水滑石上的吸附,考察了固液比（或HTlc浓度）、IBA浓度、温度及pH等因素的影响。结果表明,其吸附动力学和吸附等温线分别符合准二级吸附动力学方程和Langmiur方程;在所研究条件下,随固液比和温度增加,准二级吸附动力学速率常数（k₂）和初始吸附速率（h）均增大;pH在6.5-10.5间有利于吸附;饱和吸附量随固液比增大而降低,随温度升高而增大;由Arrhenius方程得出其吸附活化能为10.1 kJ/mol。（2）分别采用离子交换法和结构重建法合成了IBA-HTlc纳米杂化物,并进行了表征:研究了农药释放行为,考察了温度和电解质等因素的影响。根据纳米杂化物通道高度和农药分子大小推测,IBA分子在HTlc层间呈双层排列。IBA-HTlc纳米杂化物具有良好的缓释性能,其释放动力学符合准二级动力学方程;温度越高,离子强度越大,其释放速率越快。由不同温度下的准二级释放动力学速率常数（k₂）,依据Arrhenius方程得出其释放过程的活化能为16 kJ/mol。2、吡虫啉-SDS-Zn₂Al HTlc纳米杂化物合成及其释放性能研究（1）以非离子型水溶性农药吡虫啉（IM）为客体分子,以Zn₂Al HTlc为主体,采用二次组装法合成了IM-SDS-Zn₂Al HTlc纳米杂化物,并进行了表征。首先,用十二烷基硫酸钠（SDS）修饰HTlc,SDS分子插入HTlc层间将其层间距增大,形成SDS-HTlc纳米杂化物;然后,再将吡虫啉分子插入HTlc层间形成IM-SDS-HTlc纳米杂化物,其驱动力可能是浓度差。根据SDS-HTlc纳米杂化物通道高度和SDS分子大小推测,SDS分子在HTlc层间呈垂直单层排列。研究发现,吡虫啉分子的插入使SDS-HTlc纳米杂化物的层间距略有降低,可能是由于IM分子与SDS分子相互作用使SDS链弯曲所致。（2）研究了IM-SDS-HTlc纳米杂化物的释放行为,考察了电解质和pH等因素的影响。结果表明,所合成的纳米杂化物具有良好的缓释效果,其释放动力学符合准二级动力学方程;电解质的存在和低pH可增大释放速率。纳米杂化物中SDS含量(A_SDS)增加使IM的释放速率增大,可能与IM的亲水性有关。3、阿维菌素-SDS-Mg₂Al HTlc纳米杂化物合成及其释放性能研究（1）以非离子型水难溶性农药阿维菌素（AVM）为客体分子,以Mg₂Al HTlc为主体,采用二次组装蒸发溶剂促进插层（evaporating solvent enhancedintercalation method）法制备了AVM-SDS-HTlc纳米杂化物,并进行了表征。首先,将十二烷基硫酸钠（SDS）插入HTlc层间制备SDS-HTlc纳米杂化物,SDS在HTlc层间形成疏水区;其次,将SDS-HTlc纳米杂化物分散到阿维菌素的乙醇溶液中,逐渐蒸发溶剂（乙醇）,迫使疏水性的阿维菌素插入HTlc层间的疏水区,形成AVM-SDS-HTlc纳米杂化物。根据SDS-HTlc纳米杂化物通道高度和SDS分子大小推测,SDS分子在HTlc层间呈垂直单层排列,其通道高度随SDS插入量的增大略有降低。阿维菌素的插入可使SDS-HTlc纳米杂化物通道高度略有增加。（2）研究了AVM-SDS-HTlc纳米杂化物的释放行为,考察了温度、电解质和pH等因素的影响。结果表明,所合成的纳米杂化物具有良好的缓释效果,其释放动力学符合准一级动力学方程:电解质的存在、低pH和温度升高均可增大其释放速率。纳米杂化物中SDS含量增大,其阿维菌素释放速率有降低趋势,这是因为SDS含量越大,HTlc层间疏水性越强,与阿维菌素的相互作用越大。由不同温度下的准一级释放动力学速率常数（k₁）和Arrhenius方程,得出其释放过程的活化能为279 kJ/mol。更多还原

【Abstract】 Nowadays in china,the second biggest country of pesticide producing, preparations forms are mainly powder,oil concentrate and suspension concentrate, which are irrational and large application.Pesticide has brought many ignorant effects such as air pollutions,environmental destroy,food safety and so on,which has baffled agricultural sustainable development.Now the hit research trends of pesticide forms in the world are focused on controlled-release formulations.Hydtrotalcite-like compounds（HTlc）,also called Layered double hydroxides （LDHs）,consisting of divalent and trivalent metal ions and with the same layered crystal structure as hydrotalcite,are a class of layered materials which has been paid a great of attention in recent years.The interlayer region of HTlc may be considered as a microvessle,some pesticide and drug molecules may be intercalated into the gallery of HTlc to form pesticide/drug-HTlc nanohybrids.The nanohybrids may evidently inhibit the release of moleculars in the interlayer.So pesticide/drug-HTlc nanohybrids are greatly potential controlled-release formulations.HTlc was chosen as host material and some pesticides as guest species, Indole-3-buytric acid（IBA）,Avermectin（AVM） and Imidacloprid（IM） have been successfully intercalated into HTlc using different methods to obtain a series of pesticide-HTlc nanohybrids.The synthesis strategy and the properties of nanohybrids,released behavior, released mechanism and the relationship between structures and released behavior of nanohybrids were systematically studied.The main contents of this paper are as follows.1、Synthesis and characterization of IBA-HTlc nanohybrids （1） The adsorption of IBA on HTlc was studied,and some fators were investigated,for example,solid/liquid ratio（HTlc concentration）,initial concentrations,temperature and pH.It was found that the adsorption kinetics and isotherms was well fitted by pseudo-second order kinetic equation and Langmiur isotherms equation.And with the increase of HTlc concentration and temperature, the constant（k₂） of pseudo-second order kinetics and the initial adsorption rate both increase;The adsorption amount arrived maxium at pH 6.5-10.5;The adsorption capacity will decrease with the increase of solid/liquid ratio;The activation energy was calculated by Arrhenius equation.（2） IBA-HTlc nanohybrids were synthesized by exchange method and reconstruction method,which were also characterized.The release behavior was studied.The effect of temperature and electrolyte were investigated.According to the dimensions of pesticide structure and the gallery height of nanohybrids,a possible arrangement（vertical-arranging overlapped bilayer） of indole-3-buytric acid in the interlayer of nanohybrids was proposed.IBA-HTlc nanohybrids was a good controlled release pesticide formulation.And the release kinetics was well analyzed by pesudo-second-order kinetic equation.Higher temperature and electrolyte concentration,higher the release rate.According to the different values of k₂ at different temperatures and Arrhenius equation,the activation energy of release process was calculated to be 16 kJ/mol.2、Synthesis and characterization of IM-SDS-Zn₂Al HTlc nanohybrids（1） Non-ionic and water-soluble imidacloprid was chosen as pesticide guest, and Zn₂Al HTlc was the host.IM-SDS-Zn₂Al HTlc nanohybrids were synthesized by Second Assembling Intercalation method,which were also characterized. Firstly,HTlc was modified by SDS,and the basal spacing increased with the intercalation of SDS,then SDS-HTlc nanohybrids were obtained.Secondly, imidacloprid would be intercalated into the gallery of SDS-HTlc to form IM-SDS-Zn₂Al HTlc nanohybrids.The driving force may be the concentration difference.According to the gallery height of SDS-HTlc and SDS molecular structure,the possible arrangement may be vertical-arranging monolayer.It was found that the intercalation of imidacloprid induced the decrease of basal spacing of SDS-HTlc,which may be caused by the interaction of pesticide and SDS.The hydrophobic chain of SDS was distorted.（2） The release behavior was studied,and the effect of pH and electrolyte was also investigated.It was indicated that the synthesized nanohybrids could well control the release of imidacloprid.And pseudo-second order kinetic equation was satisfactory for describing the release behavior.The presence of electrolyte and lower pH would increase the release rate.The release rate will increase with the increase of SDS loading（Asps）,which may be caused by the hydrophilic property of imidacloprid.3、Synthesis and characterization of AVM-SDS-Mg₂Al HTlc nanohybrids（1） Non-ionic and poorly water-soluble avermectin（AVM） was chosen as pesticide guest,and Mg₂Al HTlc was the host.AVM-SDS-HTlc nanohybrids were synthesized by Second Assembling Intercaltion method（enhanced intercalation by evaporating solvent）.Firstly,SDS-HTlc nanohybrids were synthesized by the intercalation of SDS into the gallery of HTlc,and hydrophobic region was formed. Secondly,SDS-HTlc nanohybrids were dispersed into ethanol solution containing avermectin.Then the solvent（ethanol） was gradually evaporated out,avermetin will be forced to intercalate into the hydrophobic region of HTlc to form AVM-SDS-HTlc nanohybrids.According to the gallery height of SDS-HTlc and SDS molecular structure,the possible arrangement may be vertical-arranging monolayer.The gallery height will slightly decrease with the increase SDS loading (A_SDS).The intercaltion of avermectin slightly induced the increase of gallery height. （2） The release behavior of nanohybrids was studied,and effect of temperature,electrolyte and pH was investigated.It was found that the obtained nanohybrids were a good controlled release pesticide formulation.Its releae kinetics was better fitted by pseudo-first order kinetic equation.The presence of electrolyte,lower pH and higher temperature all increase the relase rate.The release rate will decrease with the increase of SDS loading(A_SDS),which was interpreted that higher A_SDS,stonger hydrophobicity of HTlc gallery,and the interaction between avermectin and SDS will be enhanced.Using the pseudo-first order kinetic constant with different temperatures and Arrhenius equation,the acitivation energy of release process was calculated to be 279 kJ/mol.更多还原