| With the development of research,more and more attention has been paid to the harm of UVA in sunlight,and the research on UVA protection has become one of the key points of sunscreen products study.There are three important problems with sunscreen products at present:less variety of UVA sunscreen,more difficult to stabilize the formulation of broad spectrum sunscreen lotion and the potential harm of organic sunscreen to human body and the environment.Based on these three problems,this paper took advantage of the special conjugated structure of chalcone derivative molecules as UVA filters.Chalcone derivatives and allyl polyether APEG-400 were grafted onto polymethylhydrosiloxane chains by silane addition reaction to prepare polysiloxane modified filters.The specific research results are as follows:（1）Synthesis and properties of water-soluble polysiloxane UV filter（WPUF）:The chalcone derivatives（E）-3-[4-（allyloxy）phenyl]-1-phenylprop-2-en-1-one（Blank-Cha）,（E）-3-[4-（allyloxy）phenyl]-1-（4-hydroxyphenyl）prop-2-en-1-one（Oxhydryl-Cha）and（E）-3-[4-（allyloxy）phenyl]-1-（4-methoxyphenyl）prop-2-en-1-one（Methoxy-Cha）were synthesized.WPUF was prepared by grafting Methoxy-Cha and APEG-400 onto polymethylhydrosiloxane chains through silane addition reaction.NMR,LC-MS and FT-IR were used to identify the chemical structure of the product.The properties of WPUF were tested by UV absorption spectroscopy,and the effects of different substituents on the light absorption properties and cytotoxicity of chalcone derivatives were investigated.The results showed that chalcone derivatives and WPUF had been prepared successfully.The molar absorbance coefficient of chalcone derivatives was>10000 L/（mol·cm）.Methoxy-Cha showed the lowest cytotoxicity;the chemical structure of WPUF did not change after being stored away from light for 6 months or heated at 90℃for 12 h.After 4 h of simulated sunlight exposure,the UVA absorption intensity of WPUF lost only 30.46%,and WPUF showed no cytotoxicity when the mass concentrations was≤250 mg/L.The average penetration depth of the corneum of WPUF was11μm in vitro.The in vitro SPF of WPUF was 36.21,which is comparable to commercial sunscreens.WPUF also has free radical scavenging ability and excellent solubility in water under different conditions.（2）Study on emulsifying property and UV absorption synergistic effect of WPUF:After adjusting the composition of the side chain of WPUF,the change rule of its UV absorption capacity was studied.It was found that the UV absorption capacity increased with the increase of the mass fraction of Methoxy-Cha,and the viscosity increased the same time.WPUF was designed as a water-in-silicone emulsifier with a water-in-silicone equilibrium value of 5,and was used to prepare water-in-silicone sunscreen emulsion.The stable emulsification range of the emulsifier was investigated.The influence factors and mechanism of emulsion stability were studied by means of high and low temperature circulating chamber,centrifuge,ultra depth of field microscope and rotary rheometer.The results show that the optimum emulsion preparation conditions are as follows:the oil-water ratio ranges from 25:75 to 17.5:82.5,the dosage of emulsifier is 3%and the dosage of thickening agent is 1%～3%.The addition of magnesium sulphate heptahydrate and glycerin reduced the interfacial tension to 9.93 m N/m and 5.28 m N/m,the particle size to 1.31μm and PDI to 1.128,which is conducive to the stability of the water-in-oil emulsion.In addition there are different synergistic effects between this emulsifier and the filter MBBT and A Plus.The UV-vis spectrophotometer showed that the synergistic effect of WPUF and MBBT was good,the increase maximum efficiency atλmax was2.921%,and the maximum increase of total area of curve integral of 5.237%.WPUF and A Plus have the absorption weakening effect.The maximum weakening rate atλmax was 1.220%,and the maximum weakening rate at the integrated total area was 1.871%.（3）Construction and performance of wearable skin-like sunscreen dressings（SSD）:Inspired by wearable medical skin dressings,we retained a portion of the silico-hydrogen bond on the PHMS chain in WPUF,and reformulated it with vinyl silicone oil to produce a sunscreen dressing formula that can catalytically crosslink at room temperature.The appearance of SSD was transparent.When the crosslinking density is 0.030 mmol/g,the ratio of vinyl silicone oil with different molecular weight is 165K:10K=1:4～1:5,and the addition amount of R974 is0.25%～1.0%,it is suitable for the tensile property of human skin.SSD also had high fatigue resistance and viscoelastic properties were similar to those of human epidermis.SSD was stably attached to the skin by physical anchoring,chemical bond adsorption and other factors.It could withstand the complex movement pattern of human skin and was not easy to fall off.The UVA absorption capacity of chalcone derivative structure in SSD could recover,and only 5.69%was lost after 5 cycles.The SPF value of SSD was 1190,and its water-oxygen permeability was higher than that of medical polyurethane dressings and plastic wrap.After SSD application for12 h,the water loss value of the application area continued to decrease by 45.7%compared to the baseline value.The research work of this paper shows that the strategy of grafting chalcone derivatives and APEG-400 onto polymethylhydrosiloxane chains can provide an effective solution to the problems of sunscreen products,and the prepared materials have potential applications. |
