Currently, the issue of improving the flame‐retardant performance of unsaturated polyester resin (UPR) has drawn a lot of attention. In this study, methyl vinyl di (1‐thio‐2,6,7‐trioxal‐1‐phosphabicyclo [2.2] octane‐4‐methoxy) silane (MVDOS) with P‐N‐Si‐based cage unit was synthesized, and it was utilized as a reactive flame‐retardant monomer to modify UPR. The UPR/MVDOS composites were prepared by introducing different ratios of MVDOS into UPR via the reaction of crosslink. The efficiency of the resulted composites was investigated by using the limiting oxygen index (LOI), vertical burning test, and cone calorimeter test. The results showed that the composites reached the V‐0 rate without dripping, and the LOI value was 29.1% when the content of MVDOS was as low as 18 wt%. Cone calorimeter tests revealed the peak of heat release and CO production of UPR/MVDOS‐18 were 238.2 KW/m2 and 0.0167 g/s, which were respectively lower than the ones of neat UPR. The introduction of MVDOS also increased the stability of UPR composites. Furthermore, the scattering electron microscopy, laser Raman spectroscopy, and X‐ray photoelectron spectroscopy studies revealed that the incorporation of MVDOS stimulated the UPR matrix to generate char layer with increased graphitization degree, which provided a good barrier to prevent heat and oxygen from being transferred and then protected the materials inside from further burning. This research provides a new way to obtain flame‐retardant UPR composites with high performance.
New UV-stimuli-responsive liposomes composed of two different kinds of phosphates, dipalmitoylphosphatidylcholine (DPPC) and azobenzene (Az)-containing amphiphilic phosphates were fabricated. The release behavior of calcein within the phospholipid vesicle lumen was studied by monitoring the changes of fluorescence intensity. As the results found in this paper, the instability of the lipid bilayers were caused along with the defects in the membrane regions through photoisomerization of Az, which provided a channel or increase the permeation for calcein release. The effects of Az structure and incorporation ratio were studied, with the results showing that high incorporation ratio induced high activity of release behavior. Moreover, the liposomes made by the Az with a longer hydrophobic alkyl chain gave a stable construction.
A mixture of a nitro- and methoxy-substituted azo-containing phospholipids without long alkyl tails formed vesicles showing visible light stimuli-responsive behavior. Release of encapsulated calcein from the vesicles was triggered by visible light.
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