Layer-by-layer assembly of a new l-glutamic acid based polymer with PAH: formation of hollow sphere during deposition, dye loading and chiroptical switch
作者:Xuewang Zhu、Minghua Liu
DOI:10.1039/c1sm06523h
日期:——
A new polymer with acryl backbone and L-glutamic acid (PAGlu) as the side chain was synthesized and their assembly with cationic poly(allylamine hydrochloride) (PAH) through a layer-by-layer technique was investigated. Although PAGlu dissolved in water showed no particular organized structures, it formed hollow spheres when assembling with PAH. Both SEM and TEM observation for the deposited films confirmed the hollow structure. Furthermore, observation by SEM for each deposition revealed that the hollow structure was formed during the layer-by-layer assembly process. Differently from that of the hollow capsules formed from template nanoparticles, this method provided directly the hollow structure without any template. Moreover, the water-insoluble LbL film with the hollow structure showed a rapid loading and release of dye molecules such as TMPyP (5,10,15,20-tetrakis(4-N-methylpyridyl)porphinetetra(p-toluenesulfonate)). Due to the chiral nature of the PAGlu, the loaded dye molecule showed induced chirality owing to the interaction with the L-glutamic acid moiety. In addition, this dye-loaded film can show a reversible color and chirality change upon alternative exposure to HCl and NH3 gases, realizing a gas sensing chiroptical switch.
合成了一种以丙烯酰基为主链、L-谷氨酸(PAGlu)为侧链的新型聚合物,并通过层层技术研究了其与阳离子聚(烯丙胺盐酸盐)(PAH)的组装。尽管溶解在水中的PAGlu没有表现出特殊的组织结构,但当与PAH组装时,它形成空心球体。对沉积薄膜的 SEM 和 TEM 观察均证实了中空结构。此外,对每次沉积的SEM观察表明,中空结构是在逐层组装过程中形成的。与模板纳米颗粒形成的空心胶囊不同,该方法直接提供空心结构,无需任何模板。此外,具有中空结构的水不溶性LbL薄膜表现出快速负载和释放染料分子,例如TMPyP(5,10,15,20-四(4-N-甲基吡啶基)卟啉四(对甲苯磺酸盐))。由于 PAGlu 的手性性质,负载的染料分子由于与 L-谷氨酸部分的相互作用而表现出诱导手性。此外,这种负载染料的薄膜在交替暴露于HCl和NH3气体时可以表现出可逆的颜色和手性变化,从而实现气敏手性光学开关。