Bionic structure and biocompatibilities of long chain branched poly(L-lactic acid) oriented microcellular foaming...

Area of Science:

• Polymer Science
• Biomaterials Engineering
• Materials Science

Background:

• Poly(L-lactic acid) (PLLA) exhibits challenges in achieving uniform microporous structures crucial for biomimetic applications.
• Existing methods for PLLA modification often struggle with controlling pore uniformity and maintaining mechanical properties.

Purpose of the Study:

• To address the limitations of PLLA microporous structure orientation.
• To develop a novel long chain branched PLLA (LCB-PLLA) using plant oil-derived chain extenders (CE).
• To investigate the impact of LCB structure on PLLA's crystallinity, mechanical properties, and in vitro cell response.

Main Methods:

• Reactive processing was employed to introduce multi-armed flexible chains into PLLA using biological safety multi-functional plant oil as CE.
• Optimization of CE content (6.15 wt%) to achieve maximum reaction efficiency while preserving tensile strength and enhancing toughness.
• Characterization of LCB-PLLA's crystallinity, molecular chain mobility, and microporous structure development under high draw ratios (up to 900%).

Main Results:

• The optimal CE content of 6.15 wt% led to full reaction, maintained tensile strength, and improved toughness of PLLA.
• Introduction of LCB structure significantly reduced crystallinity (45.15% for LCB-PLLA-F-900% vs. PLLA-F-900%) due to increased molecular chain mobility.
• Uniform growth of oriented microporous structures with an average cell diameter of 540 nm was achieved in LCB-PLLA.

Conclusions:

• The developed LCB-PLLA material exhibits enhanced molecular chain mobility and reduced crystallinity.
• The improved polymer chain mobility promotes uniform microporous structure formation, overcoming previous orientation challenges.
• The oriented micro-porous LCB-PLLA biomimetic material demonstrated superior performance in promoting in vitro cell proliferation.