| Recently, the topography of many biodegradable polymer surface has been prepared with a patterned nanowire surface in order to control the water contact angle, protein adsorption, and cell growth behavior on the polymer films. Thus, it is significant to study the crystallization behavior of biodegradable polymer in the cylindrical confinement. Poly(butylenes adipate) (PBA) is one of the typical biodegradable aliphatic polyesters, which exhibits two types of crystal forms, i.e. the α- and (3-forms. The P-PBA crystals are predominantly produced at low crystallization temperatures (<20 ℃). At intermediate temperature range from 20 to 33 ℃, mixed α crystals and β crystals will be developed. As the α-form crystals are structurally more stable than the (3-form crystals, the β-form crystals can transform into their α-counterparts upon heating at a slow rate or annealing at elevated temperatures (>40 ℃). PBA nanotubes were prepared by melting filtering method in alumina. In alumina nano template PBA has a completely different crystallization behavior with bulk. Crystallization and melting behavior of PBA nanotubes were investigated by differential scanning calorimetry (DSC), X ray diffraction (XRD).It is found that the PBA non-isothermal crystallization temperature decreases when PBA confined in Alumina confinement space. The isothermal crystallization temperature to form β-PBA decreases with the pore size of alumina decreases. In addition, the a-phase of PBA in the narrow nanopores prefers to adopt the orientation of b-axis parallel to the long axis of nanotubes. Confinement space greatly reduces P-PBA to a-PBA transition rate. And the β-PBA lattice coefficient along b-axis in the confined space is far less than the bulk. In the confined space melting recrystallization rate at high temperature is significantly reduced. In the confined space a large number of molecular chains can’t pack into the a-form, they pack into the P-form in the cooling process. |
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