Sun Xiaoli, Fang Qunqun, Li Huihui, Ren Zhongjie, Yan Shouke
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, China.
Langmuir. 2016 Apr 5;32(13):3269-75. doi: 10.1021/acs.langmuir.6b00251. Epub 2016 Mar 23.
Poly(butylene adipate) (PBA) was infiltrated into the anodic alumina oxide (AAO) templates with the pore diameter of around 30, 70, and 100 nm and PBA nanotubes with different diameters were prepared. The crystallization and phase transition behavior of the obtained PBA nanotubes capped in the nanopores have been explored by using X-ray diffraction and differential scanning calorimetry. Only α-PBA crystals form in the bulk sample during nonisothermal crystallization. By contrast, predominant β-PBA crystals form in the AAO templates. The β-PBA crystals formed in the nanopores with pore diameter less than 70 nm prefer to adopt an orientation with their b-axis parallel to the long axis of the pore. During the melt recrystallization, it was found that the critical temperature (Tβ), below which pure β-crystals form, is 20 °C for bulk PBA. It drops down significantly with the pore diameter for the PBA in the AAO template. Moreover, the β-crystals in the porous template exhibit larger lattice parameters compared with the bulk crystals. By monitoring the change of β-crystals in the heating process, it was found that β-crystals in the AAO template with the pore diameter of 30 nm (D30) melt directly while the β-crystals transform to α-crystals in the template with the pore diameter of 100 nm (D100). The intensity of (020) Bragg peak of β-crystals decreases at a similar rate in both D30 and D100 but disappears at a relatively lower temperature in D30. On the other hand, the β(110) peak intensity of β-PBA crystals formed in the D100 template decreases first at slower rate before α crystals appear, and then at a faster rate once the β to α phase transition takes place.
将聚己二酸丁二醇酯（PBA）渗入孔径约为30、70和100 nm的阳极氧化铝（AAO）模板中，制备了不同直径的PBA纳米管。利用X射线衍射和差示扫描量热法研究了在纳米孔中封端的所得PBA纳米管的结晶和相变行为。在非等温结晶过程中，本体样品中仅形成α-PBA晶体。相比之下，AAO模板中主要形成β-PBA晶体。在孔径小于70 nm的纳米孔中形成的β-PBA晶体倾向于采用其b轴平行于孔长轴的取向。在熔体再结晶过程中，发现对于本体PBA，低于该温度会形成纯β晶体的临界温度（Tβ）为20℃。对于AAO模板中的PBA，其随孔径显著下降。此外，与本体晶体相比，多孔模板中的β晶体表现出更大的晶格参数。通过监测加热过程中β晶体的变化，发现孔径为30 nm（D30）的AAO模板中的β晶体直接熔化，而孔径为100 nm（D100）的模板中的β晶体转变为α晶体。在D30和D100中，β晶体的（020）布拉格峰强度以相似的速率下降，但在D30中在相对较低的温度下消失。另一方面，在D100模板中形成的β-PBA晶体的β(110)峰强度在α晶体出现之前首先以较慢的速率下降，然后在β向α相变发生时以较快的速率下降。
