【作者】 贾永光；

【导师】 李靖；

【作者基本信息】 南开大学 ， 有机化学， 2012， 博士

【摘要】 主链含有大环的线形聚合物相对于一般的线形聚合物大多具有特殊的性质与重要的用途，特别是大环作为超分子体系中的受体具有重要的研究意义。Butler等人在1949年发现了一种有效制备主链含有大环结构的方法—环聚合，通过这种方法可以一步高效地完成聚合物的合成与大环结构的构筑。近年来随着可控/活性聚合技术的发展，发展可控/活性环聚合的体系用于制备主链含有大环的聚合物成为了研究热点。然而目前，对于一般的柔性双官能团单体的可控/活性环聚合的实现还具有很大的挑战。另外，PEG作为一种无毒且生物相容的材料，特别是在医药类材料中具有广泛的用途，同时也是一类很重要的温敏材料，因此PEG接枝聚合物的研究也受到人们越来越多的关注。但是主链上含有大环结构（例如冠醚）的PEG接枝聚合物的响应性质还未被涉及。同时，这些冠醚单元作为离子识别基团的荧光探针也未见有报道。本论文主要发展了一种对于含有柔性连接链的双苯乙烯单体与马来酸酐的交替可控环聚合物体系，进而得到主链上含有冠醚单元的线形聚合物，然后再通过PEG与酸酐基团的化学反应将PEG接枝到这些聚合物上，进而来研究对于温度、离子、pH等的响应性质。同时我们在此基础上进一步把荧光基团标记到这些响应性聚合物上，利用其冠醚空腔对金属离子的识别，使之构成一个探针体系，进而研究其在检测金属离子方面的实际应用。论文具体分为如下几个部分展开：首先，研究了含有三或四聚乙二醇连接链的双苯乙烯单体与马来酸酐的可逆加成-断裂链转移（RAFT）环聚合。结果聚合高产率地得到了可溶性的环聚合物。动力学研究显示，该聚合过程是可控的。运用红外、核磁、热重分析以及MALDI-TOF质谱等手段对这些新型聚合物的结构进行了全面的表征。同时，通过核磁检测发现，所得聚合物主链上的冠醚单元对有机铵盐离子具有很好的识别作用。其次，通过将PEG单甲醚接枝到上述双苯乙烯单体与马来酸酐的环聚合物上，进而合成了PEG为侧链、主链含有冠醚单元的两亲性聚合物。这些聚合物对于温度、pH、以及一些金属离子具有很好的响应性质。研究发现，这些响应性聚合物的相变温度随着侧链分子量的增加以及pH值的升高而升高。无机盐氯化钾或氯化锂的加入能够使得聚合物的相变温度降低，即表现出盐析效应。然而当加入氯化钠时，由于冠醚与钠离子的络合，使得聚合物的相变温度表现为先升高再降低。即当加入的氯化钠为5或者10mM时，其相变温度会升高，而当浓度增加到100mM时，则会使其降低。这些所加氯化钠对于相变温度的影响通过光散射也得到了确认。最后，我们通过将胺甲基Pyrene和PEG单甲醚分步修饰到双苯乙烯单体与马来酸酐的环聚合物上，得到了荧光基团Pyrene标记、PEG为侧链、且主链含有冠醚单元的、对于温度和pH都响应的两亲性聚合物。利用冠醚对于离子的识别以及金属离子对Pyrene的猝灭，将该聚合物作为检测金属离子的荧光探针。发现该类探针对于铜离子和银离子具有很高的选择性和灵敏度，对于铜离子可以达到1.02微摩，银离子达到0.75微摩的检测限。在2至12微摩之间，荧光强度与金属离子的浓度呈线性关系。另外，通过可逆加成-断裂链转移聚合（RAFT）与酯基的水解而合成了侧链含有羧酸基团的双嵌段聚合物。随后利用这些嵌段聚合物中的羧基与n-Bu₂SnO的交联，进而制备了一系列含有机锡核与聚苯乙烯壳结构的纳米粒子。这些有机锡纳米粒子的结构通过透射电镜（TEM）、扫描电镜（SEM）以及X-射线光电子能谱（XPS）等手段予以了研究。结果发现，这些纳米粒子的尺寸随着有机锡酯单元的增加而减小，同时还发现了有趣的中空结构。更多还原

【Abstract】 The polymers with the larger rings in the main chain have the special propertiesand applications, especially capturing some small molecules and ions based on thesupramolecular chemistry. The cyclopolymerization, discovered by Butler andco-workers in1949, has been considered as one of the most convenient method forthe preparation of the polymers with cyclic structures in the main chain. However, itstill remains a challenge to construct a cyclopolymerization system forming largerrings （such as crown ether） by using the flexible monomers. At the meantime,poly（ethylene glycol）（PEG） is a well-known thermo-responsive polymer and hasbeen applied for biomedical and pharmaceutical fields. And a great deal of studiesfocused on the crown ether cavities as a side pendant functional group of thepolymers since crown ethers are highly selective in the recognition of specific cations.However, it has not been studied about the responsive properties and sensorapplications of such polymers with crown ether units on the main chain and PEG asthe side chains.This thesis mainly focused on the developing a new controlled cyclopolymerizationprotocol for the common flexible monomers with maleic anhydride. Simultaneously,we also grafted PEG onto the anhydride groups of the copolymer chain andinvestigated the responsiveness of the resulting polymers. These multi-responsiveamphiphilic copolymers can also be used to detect Cu²⁺and Ag⁺as the sensor afterlabeled by the pyrene. The details are as following:Firstly, the cyclopolymerization of distyrenic flexible monomers with maleicanhydride via reversible addition fragmentation chain transfer （RAFT） has beeninvestigated. The reaction proceeded to yield gel-free copolymers soluble in organicsolvents. The kinetic study indicated that the cyclopolymerization proceeded in acontrolled manner. The structures of resulting crown ether cavity-containingcopolymers were characterized by the use of NMR spectroscopy and MALDI-TOFmass spectrometry. Additionally, it was found that the crown ether cavities of thecopolymers exhibited a selective recognition for certain dialkylammonium ions. Secondly, a series of amphiphilic copolymers were synthesized bycyclopolymerization of distyrenic monomers with maleic anhydride followed bygrafting methoxy poly（ethylene glycol） onto the anhydride groups. Theseamphiphilic graft copolymers exhibited multiple responsive toward temperature, pHand selected cations in aqueous solutions. The cloud points （CP） of the graftcopolymers increase with increasing length of the side chains and with increasing pHvalue of solution. The addition of KCl or LiCl to the solutions had a “salting-out”effect, lowering the CPs of the graft copolymers. The addition of NaCl, however,firstly raised the CP due to the complexation of the crown ether with Na+and thenlowered the CP. The light scattering results also confirmed the effect of Na+on theCP.Finally, a series of responsive copolymers （toward temperature and pH） with thecrown ether cavities in the main chain could be obtained by the labeling pyrene andgrafting PEG onto the copolymer of distyrenic monomers with maleic anhydride.These copolymers can act as metal sensors since the crown ether can capture someions and some transition metal ions can quench the fluorescence of pyrene. Thesesensors showed the highly selectivity and sensitivity toward to Cu²⁺or Ag⁺withoutinterference from other metal ions and can be used into the system of Cu²⁺and Ag⁺with the concentration of2-12μM. And the Cu²⁺or Ag⁺detection limit can be downto about1.02or0.75ppm, respectively.In addition, a series of new well-defined nanoparticles containing an organotincore and a polystyrene shell were obtained by cross-linking of n-Bu₂SnO withvarious chain-length amphiphilic copolymers. The structures of the nanoparticleswere studied by the transmission electron microscopy （TEM）, scanning electronmicroscopy （SEM） and X-ray photoelectron spectroscopy （XPS） analysis. Notably,the morphology of the cross-linked copolymer showed individual nanoparticles withregularly spherical shape. And the nanoparticle diameters decreased with increasingnumber of organotin carboxylate units.更多还原