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

摘要:

用对羟基苯甲酸（p-HBzA）对壳寡糖（OCS）进行接枝改性得到对羟基苯甲酸接枝壳寡糖（p-HBzA-g-OCS）。将p-HBzA-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-HBzA-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。

Abstract:

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