We study the influence of tip radius on the viscoelastic characterization of polymers using a recently developed loss tangent (tan δ) method operated in amplitude modulation atomic force microscopy (AM-AFM) mode. By decreasing the tip radius, we found that AM-AFM tan δ of a homogeneous polystyrene film decreased close to the bulk limit value, which can be ascribed to a reduced effect of the probe/sample adhesive interaction for a smaller tip. Decreasing the tip radius also shifted the tan δ values of nanostructured blocks in a poly(styrene-b-isoprene-b-styrene) triblock copolymer film to their bulk limits, but in different trends for glassy styrene and rubbery isoprene blocks. Besides minimizing the effect of the adhesive interaction, we demonstrate that reducing the tip radius being smaller than the characteristic size of nanostructured domains is critical to obtain their true tan δ image.

我们研究尖端半径的使用最近开发的损耗角正切（棕褐色的聚合物的粘弹性特性的影响δ）方法在调幅原子力显微镜（AM-AFM）模式下操作。通过减小尖端半径，我们发现均质聚苯乙烯薄膜的AM-AFM tan δ降低到接近体积极限值，这可以归因于探针/样品粘合剂相互作用对较小尖端的影响降低。减小尖端半径也被移位正切δ纳米结构的块的值在聚（苯乙烯- b -isoprene- b-苯乙烯）三嵌段共聚物薄膜达到其体积极限，但玻璃状苯乙烯和橡胶异戊二烯嵌段的趋势不同。除了最小化粘合剂相互作用的影响之外，我们还证明了将尖端半径减小到小于纳米结构域的特征尺寸对于获得其真实的 tan δ图像至关重要。