【作者】 朱芸；

【导师】 胡春圃；

【作者基本信息】 华东理工大学 ， 材料学， 2011， 博士

【摘要】 水性聚氨酯因其低污染和可持续发展而成为聚氨酯发展的热点。然而,水性聚氨酯大分子链中的亲水性链节或离子基团,不可避免地使其在实际使用过程中,表现出较高的吸水率和表面亲水性,限制了其在涂料、胶粘剂,以及生物医用(如软组织工程)等领域的应用。本文通过在聚氨酯脲(PUU)软段合成中使用新的二元醇和含氟单体改变PUU分子结构,制备了稳定的聚氨酯脲水分散液,其成膜后既具有较好的耐水性,又具有良好的力学性能。在此基础上,实现了聚氨酯脲水分散液中的纳米粒子对油包水(W/O)型和水包油(O/W)型Pickering高内向乳液(HIPE)的稳定,分别制备了大孔表面PUU功能化的开孔疏水性和亲水性聚合物多孔材料(Poly-Pickering-HIPEs)。PUU在HIPE中的使用丰富了水性聚氨酯脲的研究内容和应用领域,克服了传统HIPE制备中大量乳化剂使用的弊端,首次实现了同一粒子对W/O和O/W型乳液的稳定。此外,针对Poly-Pickering-HIPEs普遍具有的脆性和较低的力学性能,本文以乙烯基酯树脂(VER)为有机相,制备了具有较高压缩强度和韧性的VER基Poly-Pickering- HIPEs。主要研究结果如下：1、以C9二元醇合成的聚已二酸多元醇(POA)、聚已二酸新戊二醇酯(PNA)为原料制备和表征了一系列具有不同软段组成的PUU水分散液。结果表明,用POA可以成功地制备PUU水分散液,这些PUU水分散液具有优良的冻融稳定性和高温稳定性。在所有PUU膜中,仅含POA的水性PUU (OPU)膜的拉伸强度最大(51.3MPa),水解稳定性最好,吸水率最低。实验数据还表明,含有POA的PUU膜的耐水性能和力学性能明显提高,这是由于硬段间脲羰基的氢键作用增强引起的。2、用少量氟醇改性OPU,可以得到稳定的含氟聚氨酯脲水分散液。研究表明,此水分散液的粒径与体系中的氟含量无关,氟醇的引入可以提高改性OPU膜表面的疏水性(接触角从88°增加到113°)。当氟醇含量在3%左右时,改性膜的吸水率较低,拉伸强度较高(44.3MPa),具有较好的综合性能。随着氟醇含量的增加,改性OPU膜的硬度、拉伸强度下降,伸长率增大,这与硬段间脲羰基的氢键作用有关。3、以PUU水分散液为水相,苯乙烯(St)和二乙烯基苯(DVB)的混合物为有机相,制得了water-in-St/DVB Pickering HIPEs,并以此为模板制备了大孔表面PUU功能化的疏水性聚合物基Poly-Pickering-HIPEs。Pickering HIPE的近红外光背散射研究表明,仅由1.0wt% PUU粒子稳定的Pickering HIPEs的水相体积分数上限介于93.3和97 vol%之间,且此Pickering HIPEs具有温度依赖性。稳定机理研究表明,PUU粒子在水油界面的吸附及其在有机相中形成的3D网络结构是Pickering HIPEs稳定的关键。形貌分析表明,通过改变Pickering HIPE的水相体积分数、交联剂浓度、水相电解质浓度、PUU浓度和聚合温度可以方便地实现Poly-Pickering-HIPEs形貌调控。4、以PUU水分散液为连续相,制备了一系列分散相体积分数可达95%的O/W型Pickering HIPEs o研究表明,PUU纳米粒子有效吸附在水油界面,在分散相液滴表面形成了紧密的粒子膜,阻止了分散相液滴之间的合并；同时,PUU纳米粒子在连续相中形成了3D网络结构,提高了连续相粘度,增强了Pickering HIPE的稳定性。进一步以丙烯酰胺(AM)和N,N’-亚甲基二丙烯酰胺(MBAM)为单体和交联剂,制备了具有开孔结构的亲水性聚合物基Poly-Pickering-HIPEs.研究表明,通过乳液制备条件如水相体积分数、PUU浓度、交联剂浓度和电解质浓度等的改变,能有效实现对Poly-Pickering-HIPEs形貌的控制。5、以乙烯基酯齐聚物(VEO)的苯乙烯(St)(或甲基丙烯酸甲酯(MMA))溶液(VER)为有机相,以其中的VEO为交联剂,制备了由共聚微球稳定的W/O型Pickering HIPEs;在此基础上,制备了VER基Poly-Pickering-HIPEs。稳定性研究表明,此类Pickering HIPEs的分散相体积分数上限介于95～97 vol%之间；适当提高VER中的VEO含量,有利于Pickering HIPE的稳定。力学测试表明,此类Poly-Pickering-HIPEs表现出较高的压缩强度和韧性,其杨氏模量随着有机相中VEO含量的提高而提高。SEM分析表明,随着水相体积分数的提高和VEO含量的降低,Poly-Pickering-HIPEs的大孔平均孔径增加,孔径分布变宽。更多还原

【Abstract】 For environmental and economic reasons, waterborne polyurethane (PU) aqueous dispersions have attracted increasing interest in recent years. However, the built-in hydrophilic segments in the macromolecular chain inevitably impart undesirable water-resistance performance to waterborne PU in industrial applications. In this dissertation, a series of stable polyurethaneurea (PUU) aqueous dispersions were prepared with C9-diol-based polyester polyol (POA) and/or fluoro Oligomer(Zonyl BA-N). The PUU films prepared with these aqueous dispersions showed excellent water-resistence performance and high tensile strength. Moreover, PUU nanoparticles in PUU aqueous dispersions were used to stabilize both water-in-oil (W/O) and oil-in-water (O/W) Pickering high internal phase emulsions (HIPE). Based on these two types of Pickering HIPEs, hydrophobic and hydrophilic open porous polymers (Poly-Pickering-HIPEs) with void wall functionalized by PUU were prepared respectively. This work enlarged research fields and applications of PUU, eliminated large quantity of surfactants used in the traditional HIPEs, and firstly prepared W/O and O/W Pickering HIPE with one type of particle. In addition, some vinyl ester resin (VER)-based Poly-Pickering-HIPEs was prepared using VER as the organic phase and exhibited high compressive strength and toughness. The main results were descripted as follows:1. A series of PUU aqueous dispersions were prepared with C9-diol-based polyester polyol (POA) and/or poly(neopentylene adipate) polyol (PNA). The high-temperature stability and freeze-thaw stability for all the aqueous dispersions are excellent. The PUU film prepared only with the POA exhibited the lowest water-absorbing amount, the highest tensile strength (51.3 MPa) and the best hydrolytic stability over all PUU films studied. The experimental results also showed a high degree of hydrogen bonding for urea groups, resulting in excellent water resistance performance and mechanical properties.2. A series of stable fluoro-containing PUU aqueous dispersions were prepared from POA and fluoro oligomer(Zonyl BA-N). The particle sizes of these aqueous dispersions were less sensitive to Zonyl BA-N content. The introduction of fluoroalcohol could increase the surface hydrophobicity of modified PUU films and the contact angle of water on the surface of these films increased from 88 to 113°. When Zonyl BA-N content was about 3%, the modified PUU films showed low water absorption and high tensile strength (44.3MPa). With the increase of fluoro oligomer content, the hardness and tensile strength of the modified PUU films decreased and elongation of the films increased resulting from the strong hydrogen bonding in urea carbonyl groups in the hard segments of PUU.3. With PUU aqueous dispersion as aqueous phase and mixture of styrene (St) and divinylbenzene (DVB) as the organic phase, temperature-dependent water-in-St/DVB Pickering HIPEs were prepared. And with these Pickering HIPEs as templates, the hydrophobic polymer Poly-Pickering-HIPEs with void wall surface functionalized by PUU was prepared. The measurements of near-infrared light backscattering showed that the upper limit of internal phase volume fraction of Pickering HIPEs stabilized solely by 1.0 wt% PUU nanoparticle was from 93.3 to 97 vol%. It is of interest to note that PUU particle layers adsorption at the water-oil interface and 3D network formed by PUU particles in organic phase played key roles in the stability of Pickering HIPEs. It was also found that Poly-Pickering-HIPEs morphology could be controlled by changing the Pickering HIPE aqueous phase volume fraction, polymerization temperature, as well as the crosslinker, electrolyte and PUU concentration.4. Using PUU aqueous dispersion as continuous phase, O/W Pickering HIPEs having dispersed phase volume fraction of up to 95% were prepared. It was found that the particles membrane made by adsorption of PUU nanoparticles at water-oil interface around the dispersed phase droplet, and prevented the coalescence between the neighboring dispersed droplets; in the same time, PUU nanoparticles formed a 3D network in continuous phase, which rose the continuous phase viscosity and enhanced Pickering HIPE stability. Furthermore, with acrylamide (AM) and N,N’-methylenebis acrylamide (MBAM) as monomer and crosslinker respectively, the open porous hydrophilic polymer-based Poly-Pickering-HIPEs were prepared. It was also found that the Poly-Pickering-HIPEs morphology could be effectively controlled by changing HIPE preparation conditions, such as aqueous phase volume fraction, as well as the concentrations of PUU, crosslinker and electrolyte.5. With vinyl ester oligomer (VEO) and styrene (or methyl methacrylate) mixture (VER) as the organic phase, W/O Pickering HIPEs were prepared with copolymer microspheres as sole stabilizer. Using the Pickering HIPEs as emulsion-templating, VER-based Poly-Pickering-HIPEs were prepared. Stability studies showed that the up limited internal phase volume fraction of this type of Pickering HIPEs was between 95 and 97 vol%; an appropriate increase in the VEO content is conducive to the stability of Pickering HIPE. Mechanical test showed that the Poly-Pickering-HIPEs had high compressive strength and toughness, and its Young’s modulus increased with increasing the VEO content of the organic phase. SEM analysis showed that with increasing the aqueous phase volume fraction and/or decreasing the VEO content, the average void size of Poly-Pickering-HIPEs increased, and their void size distribution became broad.更多还原