自修复高分子.ppt

1、自修复高分子材料,自修复又称自愈合，是生物的重要特征之一。人们把在无外界作用的情况下，材料本身对缺陷自我判断、控制和恢复的能力称为自修复。当受到外界机械损害后，自修复高分子材料能自行发现裂纹，并通过一定机理将裂纹重新填补，自行愈合。,自修复高分子材料的优势,（1） 位点专一性，由裂纹引发聚合，针对性强，效率高; （2）自动化，无需人为观测，节省了监测成本; （3）提高材料寿命; （4）消除材料维护成本; （5）为材料智能化提供思路; （6）环境友好性，避免了外加添加剂对环境的影响,李思超 韩 朋 许华平 ，化 学 进 展，第 24卷 第7期 2012年 7月,一类是在材料内部复合功能型物质来实

2、现 自修复; 另一类是通过向体系提供能量，使材料本身发生共价或非共价作用实现自修复,分类,Schematic illustration of the preparation of all-water-based self-repairing super hydrophobic coatings based on U-capsules.,微胶囊的表征,a、b) SEM and TEM images of U-capsules. c) EDX spectrum of U-capsules. d) Size distribution of U-capsules measured by DLS.,Ti

3、O2具有光催化作用，在紫外光的照射下催化微 胶囊的St-DVB壳分解，释放出具有修复作用的氟 代烷基硅氧烷FAS12.,a）Schematic representation of the release mechanism in UV-responsive microcapsules,FT-IR spectra of FAS12 and the extracted ethanol of the microcapsules (T1.2-capsules: TiO2 content=1.2%; T0-capsules: TiO2 content=0).,加入TiO2的微胶囊红外图谱存在1205cm

4、-1的C-F 特征吸收峰说明TiO2的催化作用是释放FAS-12 的原因。,水性自愈合超疏水涂料的表征,超疏水材料：接触角大于150，滚动角小于10,接触角（contact angle）是指在气、液、固三相交点处所作的气-液界面的切线穿过液体与固-液交界线之间的夹角，是润湿程度的量度。,当一滴水放置在固体倾斜表面而达到一种滚动前的临界状态时，固体表面倾斜的角度就是滚动角。,十七氟癸基三乙基硅氧烷改性的二氧化硅（FMS） 未加入，接触角（WCA）只有86.5，加入25wt% 后WCA变为119.3，滚动角变为65。,Variation of WCAs with the amount of FMS

5、 nanoparticles in the U-capsules-embedded coatings (U-capsules/polysiloxane=0.36 wt/wt).,Photographs of water droplets sitting on the coated samples before a) and after b) UV irradiation in an accelerated weathering tester for 96 h.,有意思的是，经过紫外线（UV）照射一段时间后， 材料变为超疏水材料。,在紫外线的照射一段时间后接触角增大， 是由于TiO2的作用。,C

6、hange of WCA on various nanocomposite coatings before and after UV irradiation in the accelerated weathering tester for 96 h.,为观察涂料表面形貌变化，对紫外线照射前后的 试样进行TEM实验，发现照射前后表面形貌基本 一致。,The appearance of super hydrophobic coatings on different substrates after UV-irradiation: (a) paper, (b) glass, (c) tin, (d)

7、 polypropylene, (e) wood, (f) aluminum,这种涂料的作用对象广泛,紫外线照射下的耐久性,对经过不同紫外照射时间涂料的表面进行XPS 测试，微胶囊在长时间内可保持FAS12的释放。,Cross-sectional SEM images of T1.2-capsules-embedded super hydrophobic coatings before (a) and after (b) 720h accelerated weathering,对超疏水涂料720h后的电子扫描显示与之前相比 表面形貌基本一致。,b) WCAs of the coating ve

8、rsus the accelerated weathering time. Inset: the water droplets on the super hydrophobic coating after prolonged weathering for 720 h. c) WCAs of the coating panel versus outdoor exposure time. Inset: the water droplets on the coating panel after outdoor exposed for more than 720 h. Coating: T1.2-ca

9、psules/polysiloxane/FMS.,在加速和正常室外条件下进行测试，在相当长的 时间内可保持其超疏水性。,机械损伤的自愈合,a) Change of WCAs for the super hydrophobic coatings as a function of repeated polishing and accelerated weathering cycles. bd) Photographs of water droplets and contact angles on the super hydrophobic surfaces. b) Original sample.

10、 c) After 10 cycles. d) After accelerated weathering test for 84 h. Scale bars: 5 mm.,经多次砂纸打磨-紫外照射，涂料仍可保持其 超疏水性。,XPS scans of the coated surfaces (T1.21, original; T1.22, after ten cycles; T1.23, after accelerated weathering test for 84 h). Atomic compositions of the coating, T1.2-capsules/polysilox

11、ane/FMS.,对涂料表面进行XPS分析，发现紫外照射后， TiO2催化微胶囊外壳的分解释放出FAS12，修 复了机械损伤导致的接触角下降。,油污染后的超疏水性能修复,用十八烯酸污染后经紫外线照射恢复超疏水性。,ac) Photographs of water droplets and contact angles on the super hydrophobic surfaces. a) Original. b) Spread with oleic acid. c) After accelerated weathering test for 36 h. Scale bars: 5 mm,d

12、) Change of the WCAs for the super hydrophobic surfaces as a function of the cycle number of the oleic acid spreading and accelerated weathering. e) UVVis spectra of the aqueous solutions (dyed with ethylene blue) at different UV-irradiation time in the presence of the super hydrophobic coatings. Co

13、ating: T1.2-capsules/polysiloxane/FMS.,多次污染自修复后仍具有超疏水性；右图在表面 滴加甲基蓝，紫外照射一段时间后蓝色逐渐变浅。,结论,（1）经皮克林乳液聚合合成了包裹FAS12的微胶囊，加入水性聚硅氧烷 乳液中，可得到紫外诱导的超疏水自修复涂层。,（2）涂料适用范围广。,（3）经机械损伤和有机污染后可自修复恢复超疏水状态。,（4）涂料环境友好。,二硫键的重组,文献所将材料的自修复机理就是二硫键 的断裂重组。,1：TDS diol,2：tetraethyl TDS,二硫化四烷基秋兰姆（TDS）,高效液相色谱（HPLC）证实了前面所讲的二硫 键断裂重组。,V

14、ariation of molar fractions of three TDS species with time in reshuffling reactions between 1 and 2 under visible light in acetonitrile (0.02 M) at room temperature,Model reshuffling reactions in a dark place between 1 and 2 in acetonitrile (0.02 M) at room temperature,在黑暗环境下，二硫键的断裂重组需要更多 时间。这说明光引发了

15、这个反应。,ESR spectra of TDS diol 1 and tetraethyl TDS 2 in acetonitrile,电子自旋共振（ESR）发现反应中存在未配对 电子，也可验证上述过程。,反应存在两种机理，一种是自由基转移，另 一种是自由基交叉反应。,精密的高分子设计，包括结构的交换、 链的流动性和表面性质对自愈合交联聚合 物十分重要。为了使反应在室温进行，需要 一低Tg的聚合物。,Preparation of TDS cross-linked polyurethane 4 by polyaddition of TDS diol (1), TEG, TEA, and HDI

16、 in DMF with DBTDL at room temperature for 24 h.,自愈合材料的制备, 1 /TEG/TEA/HDI = 18/27/10/60.,Photographs of TDS cross-linked polymer 4a in self-healing reaction. (a) Before self-healing reaction, (b) after cutting cross-linked polymer, and (c) after self-healing reaction for 24 h.,合成的材料具备自愈合特性。,(d) Stre

17、ss-strain curve, and (e) elongation value at break (%) of cross-linked polymer 4a after irradiation of visible light at room temperature over time.,通过对不同愈合时间后的材料进行力学拉 伸，发现一段时间后材料基本恢复原来的特性。,红外图谱中不存在异氰酸酯的特征吸收峰 22752250 cm 1，排除了游离异氰酸根对修 复的影响。,IR spectrum of cross-linked polymer 4a.,a) photographs, and

18、b) Elongation values at break of 4a after self-healing reaction for 24 h in several light condition (First label: before reaction, second label: during reaction),在光照条件下形成的自由基一段时间24h仍 可起作用。,Efficiency of self-healing after extended periods of separation. Elongation value at break (%) of cross-linked polymer 4a that was left with separation in air for 4 h and 24 h, and then irradiated to visible light at room temperature for 24 h with attachmen