在线性或交联的聚氨酯粒子内原位还原制备纳米银粒子

纳米金属粒子有特异性质 ,可用作高效催化剂、非线性光学材料等 .为防止其聚集 ,不少研究者采用表面活性剂 [1]、配位体 [2 ]和高分子等以阻止纳米金属粒子的聚集 .近年来高分子金属复合纳米粒子引起人们广泛的兴趣 [3～ 9] .文献上大多采用线性或嵌段双亲高分子作纳米金属的分散稳定剂[6 ] 或在高分子粒子表面沉积纳米金属粒子[5] ,也有人采用多孔交联高分子微球的孔洞作为微反应器形成纳米金属粒子[7] .这些方法均不能有效地控制金属粒子的粒径 ,特别难以合成粒径小于 3 0 nm的银粒子 .本文首次报道了在常温处于粘弹态 ,线性或交联的高分…

In-situ Formation of Nanoparticals in Polyurethane Microspheres

Linear or cross linked aqueous polyurethane dispersions with carboxyl Ag salt were prepared. TEM photos show that Ag + was homogeneously distributed in the microspheres. The Ag + was reduced in situ by photochemical method. For linear polyurethane particles, as the extent of the reduction reaction of silver ions increased, the silver particles grew larger, but the number of the silver particles kept almost constant. In crosslinked polymer system, the number of silver particles increased, but the size of silver particles remained almost the same. We concluded that nucleation and growth of the silver particle are the result of the silver atom movement in the polymer matrix. In the linear polymer system, the movement of silver atom and aggregation of silver particles result in the formation and growth of several silver particles; in the cross linked polymer system, the polymer chain prevents the movement of silver particles, resulting in a number increase of silver particles.