Morphology Structure Of Poly(ε-caprolactone)/Poly(4-hydroxystyrene) Blend Thin Films

In this study, the blends of PVPh and PCL were chosen as sample system to study the crystallization behavior of PCL under different preparation conditions and the branched crystalline patterns of PCL of130±10nm PCL/PVPh blend films and its influence factors by using DSC、FTIR、AFM and TEM.The development of crystallinity and intermolecular interactions in PVPh/PCL blends with different blend ratios under different preparation conditions can be depicted. In the as-cast film, crystallization of PCL can take place due to the solvent effect, which reduces the interaction between the PCL and PVPh. After heat treatment process, more PCL chains are hydrogen bonded with the PVPh molecules and the interaction between PCL and PVPh is enhanced, therefore, reduces the crystallization ability of PCL.We obtained samples with diffenent H-B fractions by heat treating with different temperature to study the influence of H-B on the crystallization behavior of PCL further. The results indicate that the crystallization ability of PCL was reduced with the increase of H-B.It was found that the fraction of PVPh and the degree of supercooling has a great influence on the crystalline patterns of PCL in the PCL/PVPh blend films with thickness of130±10nm.The observation of spherulites in pure PCL film indicates the dominant mechanism of nucleation limited growth. We observed a transition between the spherulite and branch crystalline after blend the PCL with PVPh.With the increasing of PVPh fraction, compact dendrite. fractal dendrite or compact seaweed were also observed.The films with thickness of130±10nm spin-coated from PCL/PVPh(70/30) solution were chosen to study the influence of supercooling.At high supercooling, compact seaweed will be obtained; when the polymer crystallized at low supercooling, fractal dendrite structure can be observed;lower the supercooling further, we can see the compact dendrite structure. All the results indicate that diffusion controlled growth plays a leading role in PCL/PVPh blends films. We also investigated the orientation of the PCL molecular in the thin films by GIR-IR and TEM,our results showed that PCL chains are preferentially oriented in the normal direction.