对羟基苯甲酸-壳寡糖改性水性聚氨酯

Modification of Waterborne Polyurethane by p-Hydroxybenzoic Acid-Oligochitosan

用对羟基苯甲酸(p-HBzA)对壳寡糖(OCS)进行接枝改性,得到了对羟基苯甲酸接枝壳寡糖(p-HBz A-g-OCS)。将p-HBz A-g-OCS作为交联剂,与水性聚氨酯预聚体(PPU)聚合,合成了对羟基苯甲酸-壳寡糖改性水性聚氨酯(HOCS-WPU)。通过FTIR和UV-Vis证实了样品的结构;分别用DLS、力学性能分析、XRD、TGA、ABTS和DPPH自由基清除率对HOCS-WPU的性能进行了考察。结果显示:当加入质量分数为2%的p-HBz A-g-OCS(以合成PPU原料的总质量计)时,HOCS-WPU乳液粒径较小,为57.85nm,相比未改性WPU,HOCS-WPU胶膜的拉伸强度从14.03 MPa提高到16.85 MPa,结晶度从3.57%下降到3.45%;初始分解温度从204.6℃提高到216.7℃。自由基清除率测定结果显示:当HOCS-WPU的质量浓度为2.5 g/L时,该聚合物的ABTS和DPPH自由基的清除率分别达到了62%和35%,抗氧化活性相比未改性WPU明显提高。

p-Hydroxybenzoic acid grafted oligochitosan(p-HBzA-g-OCS) was obtained by graft copolymerization of p-hydroxybenzoic acid(p-HBzA) and oligochitosan(OCS).Then,it reacted with polyurethane prepolymer(PPU) to produce p-HBzA-g-OCS modified waterborne polyurethane(HOCS-WPU).The structure of the sample was confirmed by FTIR and UV-Vis.The properties were analyzed by DLS,mechanical properties measurement,XRD,TGA and radical scavenging assay of ABTS and DPPH.The results demonstrated that when the mass fraction of p-HBz A-g-OCS was 2%(based on the total mass of raw materials for synthesis of PPU),the resulting HOCS-WPU emulsion showed smaller particle size of 57.85 nm.Compared with those of unmodified WPU film,the tensile strength of HOCS-WPU film increased from 14.03 MPa to 16.85 MPa,the crystallinity declined from 3.57% to 3.45%,and the initial decomposition temperature increased from 204.6 ℃ to 216.7 ℃.The free radical scavenging assay results showed that ABTS and DPPH radical scavenging assay of the polymer reached 62% and 35% when the mass concentration of HOCS-WPU was 2.5 g/L.The antioxidant activity of HOCS-WPU was significantly better than that of the unmodified WPU.