Solid-State Crosslinkable, Shape-Memory Polyesters Serving Tissue Engineering

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials Engineering

Background:

• Developing advanced polymers with tunable properties is crucial for innovative applications.
• Shape-memory polymers (SMPs) offer unique capabilities for smart devices and biomedical implants.
• Poly(D,L-lactide)/poly(ε-caprolactone) (PDLLA/PCL) copolymers are promising biomaterials due to their biodegradability and tunable degradation rates.

Purpose of the Study:

• To synthesize and characterize acrylate-endcapped PDLLA/PCL random copolymers with varying architectures and molar masses.
• To investigate the influence of monomer content on the glass transition temperature and actuation behavior.
• To evaluate the shape-memory properties, processability via additive manufacturing, and in vitro biocompatibility of the synthesized polymers.

Main Methods:

• Synthesis of PDLLA/PCL random copolymers with acrylate end-caps in linear and star-shaped architectures.
• Differential scanning calorimetry (DSC) to determine glass transition temperatures (T_g).
• Mechanical testing to analyze viscoelastic behavior (storage modulus G').
• Shape-memory testing to quantify shape recovery (R_r) and shape fixity (R_f).
• Additive manufacturing techniques (DLP, 2PP, DPE) for polymer processing.
• In vitro biocompatibility assays (MTS, live/dead staining) using human foreskin fibroblasts (HFFs).

Main Results:

• PDLLA/PCL copolymers with tunable glass transition temperatures (10-42 °C) were synthesized by adjusting ε-caprolactone content (0-8 wt%).
• Excellent shape-memory properties were achieved with high shape recovery (88-100%) and shape fixity (78-99.5%).
• The polymers demonstrated successful processing via digital light processing, two-photon polymerization, and direct powder extrusion, retaining their shape-memory effect.
• All synthesized polymers exhibited good in vitro biocompatibility, with high metabolic activity (≈100%) and cell viability (>70%) in direct contact with HFFs.

Conclusions:

• Acrylate-endcapped PDLLA/PCL copolymers offer tunable thermal and mechanical properties for shape-memory applications.
• These polymers can be effectively processed using various additive manufacturing techniques, enabling complex structure fabrication.
• The demonstrated biocompatibility and excellent shape-memory performance make these materials highly promising for advanced biomedical devices and tissue engineering scaffolds.