A facile and efficient approach has been developed to speed up the fabrication of LBL films through sequential dipping in vigorously agitated solutions. By this agitated-dipping (AD) LBL technique, the multilayer films of PAH and PSS were fabricated. The resulting films were explored by UV-vis spectroscopy, X-ray reflectivity, and AFM. Meanwhile, the comparison of the AD and conventional LBL films was made, which demonstrated that AD LBL can decrease dipping time by more than 15 times without reducing film quality remarkably. In addition, to verify the generality of AD LBL, we studied the AD LBL films of PDDA/PSS and PAH/PAA preliminarily as well. AD LBL promotes the efficiency of conventional LBL greatly while preserving its most advantages, such as simplicity, cheapness, precise control, universality in substrates, recycling use of sample solutions, and so on. It would be a promising alternative to build up LBL films rapidly.

The synthesis of the two monomers M 1 and M2 and a series of new side-chain cholesteric liquid crystalline elastomers P2-P8 is presented. The chemical structures of the monomers and elastomers obtained were confirmed by FTIR or 1 H NMR spectroscopy. The cross-link density of the elastomers was determined by swelling experiments. The mesomorphic properties were investigated by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. Monomer M 1 showed a cholesteric phase, and M2 revealed smectic and nematic phases. The effect of the cross-link density on the phase behavior of P2-P8 is discussed. Elastomers P2-P6 containing less than 12 mol % of the cross-linking units displayed elasticity, reversible liquid crystalline phase transition, wide mesophase temperature ranges, and high thermal stability. Elastomer P 7 displayed stress-induced birefringence, and P8 showed only elasticity with no other texture. Experimental results demonstrated that the glass transition temperatures increased, and the isotropization temperatures and the mesophase temperature ranges of P 2-P6 decreased with increasing cross-link density.

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The synthesis of the nematic crosslinking agent (4′‐allyloxy‐benzoyl)‐(4″‐undec‐10‐en‐1‐oyl‐benzoyl)‐p‐benzenediolate (M‐1), the cholesteric monomer cholesteryl undec‐10‐en‐1‐oate (M‐2) and side‐chain cholesteric liquid crystalline elastomers is described. The chemical structures of the obtained monomers and elastomers were confirmed by FTIR and 1H NMR spectroscopy. Their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the crosslinking M‐1 units on phase behavior of different elastomers prepared by a one‐step hydrosilation reaction was discussed. The elastomers containing less than 20 mol‐% of the crosslinking M‐1 units showed elasticity, reversible phase transition and cholesteric texture. The experimental results demonstrated that the glass transition temperatures and isotropization temperatures of P‐2 ∼ P‐6 increased with increasing the concentration of crosslinking M‐1 units.Synthesis and schematic representation of elastomers.magnified imageSynthesis and schematic representation of elastomers.

Layer-by-layer (LBL) films of poly(lactic acid) nanoparticles (PLA NPs) and poly(ethyleneimine) (PEI) were fabricated as a novel drug-delivery system. The PLA NPs, which encapsulated pyrene as a model drug, were prepared by nanoprecipitation methods. The assembly process of PLA NPs/PEI LBL films was monitored by UV-vis spectroscopy, and the load of pyrene in the multilayer films was verified by fluorescence spectroscopy. The morphology of the PLA NPs/PEI LBL films was observed by SEM. The release profile of pyrene from the LBL films in PBS solutions was further studied, and the result indicated that the PLA NPs/PEI films were capable of sustainably releasing pyrene as expected. The fabrication of PLA NPs/PEI LBL films provides a new facile method for drug delivery and paves the way for loading multiple types of drugs into a single LBL film.