基于AFM的PCL纳米纤维动力学实验和尺寸效应研究

AN AFM-BASED DYNAMICS INVESTIGATION INTO THE SIZE-DEPENDENT BEHAVIOR OF PCL NANOFIBERS

该文通过静电纺丝法制备了直径范围在100nm-500nm之间的PCL(Poly(ε-caprolactone))纳米纤维。并成功使用原子力显微镜(AFM)测量了单根纳米纤维的动力学性能,发现PCL纳米纤维有显著的尺度效应,弹性模量随直径的减小而增加。为解释该现象,该文发展了包含应变梯度效应的两端固支纤维振动模型,利用该模型对PCL纳米纤维的尺寸效应进行了分析。结果显示,当材料尺度参数leff=78nm时,新模型与实验结果吻合良好。而应变梯度效应可忽略时,新的振动方程退化为经典的Euler-Bernoulli振动方程。

This paper presents a dynamic investigation of the polycaprolactone （PCL） nanofibers of diameters in the 100-500 nm range that were fabricated via electrospinning. We conducted AFM-based strength experiments involving a single-strand fiber and found that its elastic modulus exhibits a strong size dependency after its diameter has been reduced past a threshold size. In an attempt to explain this inverse behavior, we developed a strain gradient vibration model and used it to analyze a clamp-clamp nanofiber employed in our experimentation. As a check, our new vibration equation reverts back to the classic Euler-Bernoulli equation when strain gradient effects are neglected. To predict the onset of the inverse size-dependent response, we proposed a material length scale parameter leff and showed that at leff=78nm our theoretical predictions for the PCL nanofibers conform reasonably well to the experimental data.