表面活性剂胶束实现疏水分子在聚合物微凝胶层层组装膜中的高效负载

基于层层组装技术制备了聚烯丙基胺-葡聚糖微凝胶(记作PAH-D)/透明质酸钠(HA)膜, 将包覆有芘分子的十二烷基硫酸钠(SDS)表面活性剂胶束基于静电作用力负载到PAH-D/HA微凝胶膜中, 实现了疏水分子芘在微凝胶膜中的高效负载. 紫外-可见吸收光谱和荧光光谱证实了SDS胶束包覆的芘分子被稳定地负载在PAH-D微凝胶膜中. 透过光谱表明负载有芘分子的(PAH-D/HA)*10微凝胶膜在可见光区仍保持良好光学透过性. 芘在膜中的负载量可以通过改变PAH-D/HA微凝胶膜的沉积周期数和SDS胶束中包覆芘分子的浓度而实现调控. 具有光致变色性质的螺吡喃分子同样可以借助SDS胶束负载到PAH-D/HA微凝胶膜中, 制备具有光致变色性质的层层组装膜. 本工作为疏水有机分子在层层组装聚合物膜中的高效负载提供了一种简便、易行的方法.

High Efficient Loading of Hydrophobic Molecules in Layer-by-Layer Assembled Microgel Films with the Assistance of Surfactant Micelles

Layer-by-layer(LbL) assembly enables the fabrication of various kinds of functional films by sequential deposition of building blocks of polyelectrolytes,biomacromolecules,oligo-charged dyes,colloids,nanoparticles,polymeric complexes and so forth.However,water-insoluble organic species without necessary functional groups are difficult to be incorporated into multilayer films by conventional LbL assembly method.The present work aims to develop a facile method for efficient loading of hydrophobic molecules into LbL assembled films.To do so,PAH-D microgels,which are chemically cross-linked poly(allylamine hydrochloride)(PAH) and dextran,are LbL assembled with hyaluronic sodium(HA) to produce PAH-D/HA microgel films.Sodium dodecylsulfate(SDS) micelles are used as carriers to incorporate hydrophobic molecules of pyrene and spiropyran.The negatively charged SDS micelles loaded with hydrophobic molecules are successfully incorporated into the PAH-D/HA microgel films by a post-diffusion process,which produces transparent PAH-D microgel films with a large number of loaded pyrene and spiropyran molecules.Fluorescence emission spectra support that the hydrophobic molecules in PAH-D/HA films locate in the hydrophobic cores of SDS micelles.Stable loading of SDS micelles into PAH-D/HA films is achieved because of the strong electrostatic interaction between SDS micelles and protonated amine groups of PAH-D microgels.The high loading capacity of PAH-D/HA films toward SDS micelles encapsulated with hydrophobic molecules originates from the high swellability of the PAH-D/HA films and the abundance of unpaired amine groups in the PAH-D layers for binding of SDS micelles.The amount of hydrophobic molecules loaded into PAH-D/HA microgel films can be conveniently controlled by varying the deposition cycles of PAH-D/HA films and the concentration of hydrophobic molecules encapsulated in SDS micelles.The spiropyran-loaded PAH-D/HA microgel films show reversible photochromic property upon ultraviolet and visible light irradiation.The present work opens a cost-effective and general way to incorporate non-charged hydrophobic molecules into LbL assembled microgel films by using surfactant micelles as carriers.