Synthesis and solution behavior of poly(ε-caprolactone) grafted hydroxyethyl cellulose copolymers

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials

Background:

• Hydroxyethyl cellulose (HEC) is a water-soluble polymer with diverse applications.
• Grafting poly(ɛ-polycaprolactone) (PCL) onto HEC can introduce tunable hydrophobic properties.
• Developing novel amphiphilic copolymers is crucial for advanced material applications.

Purpose of the Study:

• To synthesize and characterize novel poly(ɛ-polycaprolactone) grafted hydroxyethyl cellulose (HEC-g-PCL) copolymers.
• To investigate the self-assembly behavior and solution properties of these copolymers.
• To explore the influence of grafted PCL content on copolymer characteristics.

Main Methods:

• Synthesis of trimethylsilylated hydroxyethyl cellulose (TMSHEC) using hexamethyldisilazane (HMDS).
• Homogeneous ring-opening graft polymerization of PCL onto HEC, followed by deprotection.
• Structural characterization using Fourier-transform infrared spectroscopy (FTIR) and 1H Nuclear Magnetic Resonance (NMR).
• Analysis of solution properties including fluorescence spectroscopy, surface tension measurements, and rheology.

Main Results:

• Successful synthesis of HEC-g-PCL copolymers with controlled PCL grafting.
• Copolymers exhibit self-assembly into hydrophobic microdomains in aqueous solutions.
• Critical association concentration (cac) decreases with increasing PCL content.
• Surface tension reduction and increased hydrodynamic radius of aggregates with higher PCL content.
• Significant increase in zero-shear viscosity above cac for copolymers compared to HEC.

Conclusions:

• HEC-g-PCL copolymers demonstrate tunable amphiphilic behavior and self-assembly.
• Grafting PCL onto HEC provides a versatile platform for creating functional polymeric materials.
• The observed changes in solution properties are directly related to the degree of PCL grafting and self-assembly.