Abstract:
The research aimed to prepare photocrosslinkable bio- based block copolymers consisting of polymethacrylic acid-block-polycinnamyl methacrylate-block-poly methacryliciodide acid as polymer shells for Kaffir lime oil.
First, cinnamyl alcohol which was used as a biomonomer was functionalized with methacrylic anhydride via an esterification reaction to create a double bond named cinnamyl methacrylate. Then, it was copolymerized with methacrylic acid using solutioniodine transfer polymerization, resulting in polymethacrylic acid-block-polycinnamyl methacrylate-block-poly methacrylic acid (PMAA-b-PCMA-b-PMAA) with a molecular weight of 2800 g/moland a chain length equals to7: 6: 7 units. After that, PMAA-b-PCMA-b-PMAA (BioSurf) was used as polymer shells to encapsulate Kaffir lime oil in a microemulsion system cooperated with Tween 80 (surfactant; Surf) and ethanol (co-surfactant; CoSurf). The ratio of Kaffir lime oiland Surf-CoSurf was varied from 1: 9 to 9: 1(wt). The Surf[subscriptmix] which consisted ofBioSurf,Surf and Co-Surf at the ratio of 1: 1: 1 (wt) was dispersed in water at 400 rpm for 5 min. The optimal contents of oil, Surf[subscriptmix],and water were 6, 24, and 70%, respectively. The nanocapsule size was about 68 nm with -3.64 mV. After UV curing at 254 nm for 120 min, the dimerization of cinnamyl groups in PCMA was confirmed bythe UVspectroscopy. The result revealed that the absorbance peaks of cinnamyl groups at 283 and 294 nm significantly decreased. It was found that 10% of the encapsulated Kaffir lime oil slowly permeated into skin after 1 h. In addition, the oil also had anti- inflammatory effects with the percentage of inhibited nitric oxide production in macrophage cells at 32.07 [dotplus] 0.63. Moreover, nanocapsules did not show toxicity to human skin cells at the concentrations of less than or equal to 1 v/v%. Finally, the microemulsion was thermodynamically stable at 4, 30, and 45 degree Celsius.