Photo-induced reversible uniform to Janus shape change of vesicles composed of PNIPAM-b-PAzPy2
Photo-induced reversible uniform to Janus shape change of vesicles composed of PNIPAM-b-PAzPy2
复制标题
由 PNIPAM-b-PAzPy2 组成的囊泡光诱导可逆均匀至 Janus 形状变化
DOI：
10.1039/c2sm27738g
复制
发表时间：
2013-01-01
期刊：
影响因子：
3.4
通讯作者：
Zhang, Qijin
中科院分区：
文献类型：
--
作者：
Shen, Guangyong;Xue, Guosheng;Zhang, Qijin
本工作中，通过两亲性嵌段共聚物（BCP）的自组装制备了三种囊泡，其中疏水链分别为具有0、2和6个亚甲基单元的侧链偶氮苯聚合物。已经发现，由具有0个亚甲基单元的间隔基的BCP形成的囊泡没有光响应行为，并且具有6个间隔基的囊泡在365 nm的光照射下具有光诱导溶胀行为。出乎意料的是，由间隔基为2的BCP形成的囊泡在相同的照射下显示出可逆的均匀的Janus形状变化。这种可逆的过程意味着囊泡的形状变化可以通过UV光的切换来控制。紫外-可见吸收光谱和激光捕获的拉曼光谱（LTRS）被用来研究这些囊泡的形态和光诱导行为的差异。结果证实，由间隔基为2的BCP形成的囊泡的光诱导Janus形状是亚稳态形状，不同于由间隔基为0的BCP形成的囊泡的稳定Janus形状。双光子共聚焦激光扫描显微镜（CLSM）也证实了这一点。结果表明，BCP疏水链中间隔基的长度对BCP形成的囊泡的光诱导行为有重要影响，这将是设计具有特殊形貌的功能囊泡的关键。
In this work, three kinds of vesicles are fabricated by the self-assembly of amphiphilic block copolymers (BCPs), in which the hydrophobic chains are side chain azobenzene polymers with spacers of 0, 2 and 6 methylene units, respectively. It has been found that vesicles formed by BCPs with a spacer of 0 methylene units have no photo-responsive behavior and vesicles with a spacer of 6 have a photo-induced swelling behavior under the irradiation of light at 365 nm. Unexpectedly, the vesicle formed by BCPs with a spacer of 2 shows a photo-induced reversible uniform to Janus shape change under the same irradiation. This reversible process means that a bistable shape change of the vesicle can be controlled by the switching of UV light. A UV-visible absorption spectrum and a laser-trapped Raman spectrum (LTRS) are used to investigate differences in the morphology and photo-induced behavior of these vesicles. Results have confirmed that the photo-induced Janus shape of vesicles formed by BCPs with a spacer of 2 is a metastable shape, different from the stable Janus shape of vesicles formed by BCPs with a spacer of 0. This is also testified by a two-photon confocal laser scanning microscope (CLSM). From the results it is realized that the spacer length in the hydrophobic chains of BCPs can affect the photo-induced behavior of vesicles formed by BCPs, which will be a key point in designing functional vesicles with special morphologies.