针对核活动中可能产生的放射性气溶胶污染,以聚乙烯醇为基材,丙烯酰胺为改性功能单体,采用自由基溶液聚合方法,制备出高黏度的具有交联网络结构的水溶性放射性气溶胶压制剂。通过红外光谱和核磁表征表明,丙烯酰胺与基材发生了接枝反应;...针对核活动中可能产生的放射性气溶胶污染,以聚乙烯醇为基材,丙烯酰胺为改性功能单体,采用自由基溶液聚合方法,制备出高黏度的具有交联网络结构的水溶性放射性气溶胶压制剂。通过红外光谱和核磁表征表明,丙烯酰胺与基材发生了接枝反应;通过扫描电镜测试对放射性气溶胶压制剂的微观形貌观察可知,压制剂具有交联网状多孔洞结构;经过差示扫描量热分析、热重表征,由于具有交联结构,分子链运动受阻,与均聚丙烯酰胺比较,玻璃化转变温度提高了1.48℃,熔点降低了9.81℃,初始分解温度提高了18.12℃,无序性增大,结晶性减弱,热稳定性增强;模拟喷淋雾化试验测试其压制效果,黏度为1755 m Pa·s的压制剂效果可达到68.54%。展开更多
In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effect...In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effects.Based on the step-growth nature of hydroxyls and isocyanates,the architectures of the networks were adjusted by controlling the stoichiometries of chemical materials.A uniform monodomain sample was prepared by external stress relaxation via a reversible addition reaction of a dynamic carbamate bond.Two independent transition temperatures assigned to glass transition temperature/melting temperature and liquid crystal phase transition temperature were employed to thermally trigger triple shape memory effects and two-way autonomous actuation.In addition,taking advantage of the trans-cis photoisomerization of azobenzene,the programmed network showed a reversible bending and unbending shape change upon irradiation by visible light at450 and 550 nm,respectively.Coupling the autonomously thermo-induced contraction/extension actuation and reversible photo-induced bending/unbending behaviors of PULCN(AZO)s in one system will expand their potential applications in emerging multifunctional devices.展开更多
文摘针对核活动中可能产生的放射性气溶胶污染,以聚乙烯醇为基材,丙烯酰胺为改性功能单体,采用自由基溶液聚合方法,制备出高黏度的具有交联网络结构的水溶性放射性气溶胶压制剂。通过红外光谱和核磁表征表明,丙烯酰胺与基材发生了接枝反应;通过扫描电镜测试对放射性气溶胶压制剂的微观形貌观察可知,压制剂具有交联网状多孔洞结构;经过差示扫描量热分析、热重表征,由于具有交联结构,分子链运动受阻,与均聚丙烯酰胺比较,玻璃化转变温度提高了1.48℃,熔点降低了9.81℃,初始分解温度提高了18.12℃,无序性增大,结晶性减弱,热稳定性增强;模拟喷淋雾化试验测试其压制效果,黏度为1755 m Pa·s的压制剂效果可达到68.54%。
基金supported financially by the National Natural Science Foundation of China(51773131 and 51721091)the Fundamental Research Funds for the Central Universities。
文摘In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effects.Based on the step-growth nature of hydroxyls and isocyanates,the architectures of the networks were adjusted by controlling the stoichiometries of chemical materials.A uniform monodomain sample was prepared by external stress relaxation via a reversible addition reaction of a dynamic carbamate bond.Two independent transition temperatures assigned to glass transition temperature/melting temperature and liquid crystal phase transition temperature were employed to thermally trigger triple shape memory effects and two-way autonomous actuation.In addition,taking advantage of the trans-cis photoisomerization of azobenzene,the programmed network showed a reversible bending and unbending shape change upon irradiation by visible light at450 and 550 nm,respectively.Coupling the autonomously thermo-induced contraction/extension actuation and reversible photo-induced bending/unbending behaviors of PULCN(AZO)s in one system will expand their potential applications in emerging multifunctional devices.