Structure and surface nanomechanics of poly(l-lactide) from thermally induced phase separation process

详细信息	查看全文 | 推荐本文 |

• 作者：Jundong Shao^a ; ^b ; ^c ; Cong Chen^a ; ^b ; ^c ; Yingjun Wang^a ; ^b ; ^c ; Xiaofeng Chen^a ; ^b ; ^c ; Chang Du^a ; ^b ; ^c ; ^{duchang@scut.edu.cn}
• 关键词：Poly(l-lactic acid) nanofibers ; Thermally induced phase separation ; AFM ; Nanoindentation
• 刊名：Applied Surface Science
• 出版年：2012
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：15 June, 2012
• 卷：258
• 期：17
• 页码：6665-6671
• 文件大小：1383 K

摘要

The surface morphology, crystalline structure and nanomechanical properties of poly(l-lactide) (PLLA) samples prepared via thermally induced phase separation (TIPS) process have been investigated by scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), wide-angle X-ray diffraction (WAXD), atomic force microscopy (AFM), force spectroscopy and nanoindentation. Typical nanofibrous scaffold was obtained at 鈭?4 掳C (NF sample) while a denser matrix with some plateletlike structure was obtained at 15 掳C (PL sample). The NF sample has a higher crystallinity with 伪鈥?form crystals while the PL sample has 伪-form crystals embedded in a largely amorphous matrix. The two kinds of samples have differences in the chain conformation with a more restricted backbone vibration and stiffened segmental motion in NF samples. The NF samples have a higher adhesion force although both samples showed a heterogeneous distribution of adhesion force on the surface based on force spectroscopy analysis. The alternating distribution of domains with higher and lower adhesion force exhibited a banded pattern on PLLA nanofibre. This pattern is proposed to reflect the distribution of crystal-rich and amorphous-rich domains in the semicrystalline samples. AFM-based nanoindentation test indicated that the nanofibrous NF samples can have more significant plastic deformation and creep than the largely amorphous PL samples. The sliding of the crystal-rich domains along the fibrils would account for this increased plasticity of the nanofiber.