【作者】 陈友汜；

【导师】 杨慕杰； 李扬；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2007， 博士

【摘要】 本论文设计制备了四种类型共七种高分子及复合高分子湿敏材料:基于聚4-乙烯基吡啶/聚甲基丙烯酸缩水甘油酯(P4VP/PGMA)互穿网络聚合物(IPN);基于聚甲基丙烯酸二甲氨基乙酯/聚甲基丙烯酸缩水甘油酯(PDMAEM/PGMA)互穿网络聚合物及其分别与聚苯胺(PANI-CSA)或聚吡咯(PPy)的复合物;聚苯乙烯磺酸钠(NaPSS)以及聚二甲基二烯丙基氯化铵(PDDA)聚电解质材料与多壁碳纳米管复合物,和羧基改性超支化聚合物H20。通过浸涂法在金叉指电极表面涂膜,再经过加热处理,同时进行季铵化、交联反应,方便地制备互穿聚合物网络湿敏元件及其它湿敏元件。另外,采用气相聚合、溶液原位生长、静电纺丝三种方法直接制得了聚吡咯、聚吡咯/多壁碳纳米管复合物以及聚吡咯复合物纳米纤维气敏材料及气体敏感元件。使用FT-IR、UV-vis、XRD、TGA、TEM、SEM、AFM和拉曼光谱等手段表征了材料组成和形貌。研究了湿敏元件的湿敏特性以及气敏元件对氨气、甲醇等有机气体的气敏特性。讨论了敏感层的组成、结构及其微观形貌,制备工艺条件等因素对敏感元件响应性能的影响。探讨了敏感材料的湿敏或气敏机理。研究了制备互穿聚合物的浸涂液总浓度、浸涂液中互穿聚合物组成比例、交联剂浓度、制备工艺(电极结构、浸涂液陈化时间、季铵化温度及时间、敏感层的厚度、保护膜)以及测试环境(测试温度、频率)等,对基于P4VP/PGMA互穿聚合物网络(IPN)湿敏元件感湿特性的影响。与基于单一亲水、疏水网络或半互穿网络的元件相比,制得的电阻型湿敏元件,不仅在95～25%RH范围,阻抗变化范围10~3～10~6Ω,具有响应快(吸湿3 s、脱湿时间21 s),灵敏度高(10~3),湿滞小(～1%RH)以及线性度好(R~2=0.996)等优异的湿敏响应特性,而且还具备良好的耐高温高湿、耐水、耐溶剂特性。通过交流复阻抗谱分析,研究其湿敏特性并建立等效模型,其湿敏行为与典型聚电解质湿敏材料相一致,导电机理主要为离子导电,而亲疏水组分的比例是决定元件表现为电阻型响应或电容型响应的关键。研究了互穿聚合物的组成、制备工艺,对基于PDMAEM/PGMA IPN湿敏元件的感湿特性的影响,发现该元件在98～18%RH湿度范围内,阻抗变化范围10~3～10~7Ω,同样具有响应快(吸湿4 s、脱湿20 s),灵敏度高(～10~4),湿滞小(～2%RH)等优良的湿敏响应特性,同时还发现该元件具有良好的耐水性(20 min)。同时,以该湿敏膜为基,采用聚吡咯的气相聚合法,或涂覆可溶聚苯胺,制得了复合湿敏元件。发现复合元件不仅基本保留了IPN湿敏元件原有的湿敏特性,而且低湿条件下的阻抗明显降低,有利于较低湿度环境(15～30%RH)的检测。研究了多壁碳纳米管的引入对聚苯乙烯磺酸钠、聚二甲基二烯丙基氯化铵湿敏响应特性的影响,讨论了复合物组成对其湿敏特性及其湿敏机理的影响。元件在98～20%RH范围的阻抗随湿度降低线性减少,为较低湿度的测量提供了基础。该类复合湿敏元件的感湿行为主要受离子导电与本征电子导电两种机理所控制。初步探讨了通过端基改性制备基于超支化聚酯H20的湿敏材料,及其湿敏元件的感湿特性。发现羧基改性超支化H20湿敏材料随末端基的性质和数量的不同,其表现出不同的湿敏特性。研究了氧化剂、掺杂剂种类和浓度以及多壁碳纳米管的引入,对气相聚合制备的聚吡咯及其纳米复合物氨气响应特性的影响。发现多壁碳纳米管的引入可提高纳米复合物对氨气的响应灵敏度,其对50 ppm氨气的灵敏度高达10%,同时在很高的氨气浓度下(12500 ppm)响应也可回复,显示良好的应用前景。研究了制备工艺条件对溶液原位生长制备的聚吡咯元件的氨气敏感特性的影响,制得的元件对低浓度的氨气(32～550 ppm)也表现出良好的可逆线性响应。初步研究了静电纺丝制得的聚吡咯复合物纤维元件的氨气敏感特性,其与薄膜元件相比具有更高响应灵敏度、更好的回复性。讨论了聚吡咯及其复合物的气体敏感机理,发现氧化剂、掺杂剂种类和多壁碳纳米管,对聚吡咯及其纳米复合物氨气响应灵敏度及回复性有明显的影响。更多还原

【Abstract】 Four types of humidity sensitive materials based on polymer and polymer composite were designed and prepared,including an interpenetrating polymer network （IPN）composed of poly（4-vinylpyridine）and poly（glycidyl methacrylate） （P4VP/PGMA）,an IPN composed of poly（N,N’-dimethylaminoethyl methacrylate）and poly（glycidyl methacrylate）（PDMAEM/PGMA）and its composites with polyaniline （PANI）or polypyrrole（PPy）,a composite of sodium polystyrenesulfonate（NaPSS）and multi-walled carbon nanotube（MWNT）and a composite of poly（diallydimethylammonium chloride）（PDDA）and MWNT,and a hyperbranched polyester undergoing terminal group modification.Humidity sensors were prepared by dip-coating these sensitive materials on the interdigital gold electrodes.In particular,the sensors were heated to initiate the simultaneous quaternization and crosslinking reactions to form the IPN structure.Furthermore,gas sensitive materials and gas sensors based on PPy and its composites with MWNT or polymers were prepared by the method of vapor phase polymerization,in-situ solution polymerization and electrospinning.The compositions and morphologies of the sensitive materials were characterized by means of FT-IR,UV-vis,XRD,TGA,SEM,TEM,AFM,Raman spectroscopy,etc.The humidity sensitive properties of the polymer and polymer composites were investigated at room temperature,together with the gas sensitive properties of PPy and its composites towards NH₃,methanol vapor,etc.The effects of the composition,structure and morphology of the sensitive films,preparation techniques on the sensing characteristics of the humidity and gas sensors were discussed.The humidity and gas sensitive mechanisms were explored.The effect of the concentration of dip-coating solution,ratio of the two polymer components,the concentration of crosslinking agents,the preparation techniques （electrode structure,temperature and time of quaternization reaction,aging time, thickness of the sensitive film,protection film,etc.）and the measuring conditions on the humidity sensitive properties of P4VP/PGMA IPN was investigated.It was found that the polymer network exhibited an impedance change of 10³～10⁶Ωin the range of 95～25%RH,indicating a high sensitivity.In addition,it showed a fast response （response time of 3 s and 21 s for adsorption and desorption,respectively）,small hysteresis（～1%RH）and good linearity（R²=0.996）.Besides,it was also featured with good durability to high temperature and high humidity,and high resistance to water and solvents.The investigations on the humidity sensitive mechanism by complex impedance spectra revealed that the polymer composite showed sensing characteristics typical of polyelectrolytes,and ion conductivity played a major role in its conduction behavior.The ratio of hydrophobic to hydrophilic components in the polymer network determined whether it exhibited a resistive-type or capacitive-type response.The effect of the composition and preparation conditions on the humidity sensitive properties of PDMAEM/PGMA IPN was investigated.It was found that the polymer network exhibited an impedance change of 10³～10⁷Ωin the range of 98～18%RH.In addition,it was also featured with a fast response（response time of 4 s and 20 s for adsorption and desorption,respectively）,small hysteresis（～2%RH）and high resistance to water.The polymer network was covered by a layer of vapor phase polymerized PPy or soluble PANI to prepare composite humidity sensors.It was found that the composite not only maintained the good humidity sensitive properties of the PDMAEM/PGMA IPN,but also exhibited a much smaller resistance at low humidity,which facilitated the measurement of low humidities（15～30%RH）.The effect of introduction of MWNT on the humidity sensitive properties of the composite of NaPSS and PDDA with MWNT was investigated.And the exploration of its sensing mechanism revealed that its conduction behaviors were related to both ionic and electronic conduction.The humidity sensitive properties of hyprebranched polyester（H20）whose terminal hydroxyl group was converted to carboxylic group were investigated.It was found that the properties and numbers of terminal groups of modified H20 affected its humidity sensitive properties.The effect of the properties and concentration of oxidants and dopants,and the introduction of MWNT on the gas sensitive properties of PPy and its nanocomposites prepared by vapor phase polymerization towards NH₃ vapor was investigated.It was found that the inclusion of MWNT improved the sensitivity of the nanocomposite, reaching 10%towards NH₃ vapor of 50 ppm.In addition,a reversible response was observed in the sensing of high concentration NH₃ vapor（12500 ppm）,which indicates its great potentials for practical applications.The effect of the preparation conditions on the NH₃ sensitive properties of PPy prepared by in-situ solution polymerization was investigated,and a reversible and linear response towards NH₃ vapor of very low concentrations（32～550 ppm）was observed.The gas sensitive properties of fibers of PPy and its composite obtained by electrospinning towards NH₃ vapor was investigated, and the fibers exhibited a higher sensitivity and better reversibility than the thin films of PPy and the composite.The exploration on their gas sensitive mechanism revealed that the properties of oxidants and dopants,the introduced MWNT all have great effect on their sensitivity and reversibility in the detection of NH₃ vapor.更多还原