Effect of soft segment crystallization and hard segment physical crosslink on shape memory function in antibacterial...

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Shape memory polyurethane (SMPU) ionomers are advanced materials with potential applications in various fields.
• Introducing antibacterial properties into SMPU ionomers is crucial for biomedical and hygiene-related applications.
• The effect of ionomer content on mechanical properties and shape memory behavior needs further investigation.

Purpose of the Study:

• To synthesize novel SMPU ionomers with integrated antibacterial activity.
• To investigate the influence of varying pyridinium content on the mechanical properties, shape memory behavior, and antibacterial efficacy of SMPU ionomers.
• To evaluate the substrate bonding antibacterial activity of the synthesized SMPU ionomers.

Main Methods:

• Synthesis of SMPU ionomers using poly(epsilon-caprolactone)diol, 4,4'-diphenylmethane diisocyanate, 1,4-butanediol, and N,N-bis(2-hydroxyethyl)-isonicotinamide.
• Introduction of antibacterial activity via pyridinium formation through neutralization with 1-iodooctane.
• Characterization using tensile testing, dynamic mechanical analysis, and cyclic tensile investigation.
• Antibacterial activity assessment using AACTT 147 and ASTM E2149 standards against Staphylococcus aureus and Klebsiella pneumoniae.

Main Results:

• Increased pyridinium content (6.72 and 29.55 mol.%) in SMPU ionomers decreased mechanical properties at elevated temperatures.
• Shape memory function is significantly influenced by soft segment crystallization and hard segment physical crosslinking.
• High shape fixity ratios (up to 93.8%) were achieved rapidly (30 s cooling) with higher pyridinium content due to disrupted physical crosslinking.
• Synthesized SMPU ionomers demonstrated excellent substrate bonding antibacterial activity, with 100% reduction against Staphylococcus aureus and 83.6-90.7% reduction against Klebsiella pneumoniae.

Conclusions:

• SMPU ionomers with varying pyridinium content exhibit tunable mechanical properties and shape memory characteristics.
• The incorporation of pyridinium effectively imparts significant antibacterial activity to SMPU ionomers.
• These novel SMPU ionomers show promise for applications requiring both shape memory and robust antibacterial functionalities.