Stereocomplexation of high-molecular-weight enantiomeric poly(lactic acid)s enhanced by miscible polymer blending with hydrogen bond interactions

Published Date

19 August 2016, Vol.98:80–87, doi:10.1016/j.polymer.2016.06.014

Title 

Stereocomplexation of high-molecular-weight enantiomeric poly(lactic acid)s enhanced by miscible polymer blending with hydrogen bond interactions

• Author 

• Pengju Pan ^,
• Jianna Bao
• Lili Han
• Qing Xie
• Guorong Shan
• Yongzhong Bao

• State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China

Received 20 January 2016. Revised 14 April 2016. Accepted 6 June 2016. Available online 7 June 2016.

Highlights

• •
  A method is found to enhance the stereocomplexation of HMW PLLA/PDLA blend by miscible polymer blending with H-bonds.
• •
  Blending with PVPh increases the SC content of PLLA/PDLA blend.
• •
  Mechanism for the preferred stereocomplexation of PLLA/PDLA/PVPh blend is proposed.

Abstract

A feasible approach is proposed to enhance the ability of stereocomplex (SC) crystallization and depress the homocrystallization in high-molecular-weight (HMW) poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic blends by miscible polymer blending with hydrogen bond interactions. Poly(vinyl phenol) (PVPh) is selected as a model polymer and blended with PLLA and PDLA at different compositions. Crystallization kinetics, polymorphic crystalline structure, and lamellae morphology of PLLA/PDLA/PVPh ternary blends were investigated and compared with the PLLA/PDLA racemic blend. The crystallization rate and spherulitic growth rate of PLLA/PDLA blends are decreased after blending with PVPh. However, the content of SCs in the ternary blends are enhanced under the nonisothermal and isothermal crystallizations at different temperatures. SCs are predominantly generated in the PLLA/PDLA/PVPh blends with relative high PVPh content. Long periods of both SCs and homocrystallites increase with increasing the PVPh content, indicating that the noncrystallizable PVPh component is segregated into the interlamellae region of crystalline phase. It is proposed that the preferred SC crystallization of PLLA/PDLA blends upon miscible blending with PVPh is caused by the increased intermolecular interactions, decreased diffusion pathway of enantiomeric chains, and the decreased melting point.

Graphical abstract

Keywords

• Poly(lactic acid)
• Poly(vinyl phenol)
• Stereocomplex
• Hydrogen bond

---

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

 Table 1

Table 1.

Fig. 8.

• PDF (491K)

• ∗ 
  Corresponding author.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S003238611630489X