Abstract
In this work, we investigated the bulk phase distinguishing of the poly(ε-caprolactone)-polybutadiene-poly(ε-caprolactone) (PCL-PB-PCL) triblock copolymer blended in epoxy resin by tapping mode atomic force microscopy (TM-AFM). We found that at a set-point amplitude ratio (rsp) less than or equal to 0.85, a clear phase contrast could be obtained using a probe with a force constant of 40 N/m. When rsp was decreased to 0.1 or less, the measured size of the PB-rich domain relatively shrank; however, the height images of the PB-rich domain would take reverse (translating from the original light to dark) at rsp = 0.85. Force-probe measurements were carried out on the phase-separated regions by TM-AFM. According to the phase shift angle vs. rsp curve, it could be concluded that the different force exerting on the epoxy matrix or on the PB-rich domain might result in the height and phase image reversion. Furthermore, the indentation depth vs. rsp plot showed that with large tapping force (lower rsp), the indentation depth for the PB-rich domain was nearly identical for the epoxy resin matrix.
Highlights
Tapping mode atomic force microscopy (TM-AFM) has become a widely used technique to study the structures and properties of heterogeneous polymers at nanometer scale [1,2,3,4,5,6,7,8,9]
Structure of PCL-PB-PCL-blended epoxy resin film To unambiguously identify the components of the blends, transmission electron microscopy (TEM) image was taken
A series of phase and height images were obtained at given amplitude (A0) = 60 nm with rsp which varied from 0.1 to 0.95
Summary
Tapping mode atomic force microscopy (TM-AFM) has become a widely used technique to study the structures and properties of heterogeneous polymers at nanometer scale [1,2,3,4,5,6,7,8,9]. In a TM-AFM measurement, a cantilever is forced to oscillate with the probe tip at a given amplitude (A0). The cantilever is brought close to the specimen and made to tap the surface with a given reduced set-point amplitude (Asp). Height image can reflect the topographical and morphological structures, while phase images are sensitive to the physical and chemical properties of the studied material, such as stiffness, viscoelasticity, and chemical composition [3,10,11,12]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call