Thermoresponsive hydroxybutylated starch nanoparticles

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Starch nanoparticles (SNPs) are eco-friendly materials with a decade of research.
• Thermoresponsive SNPs, crucial for advanced applications, have not been previously reported.
• Potential applications exist in medicine, food, and composites.

Purpose of the Study:

• To prepare and characterize novel thermoresponsive SNPs.
• To investigate the influence of chemical modification and environmental factors on SNP thermoresponsivity.

Main Methods:

• Synthesis of hydroxypropyl (HP) and hydroxybutyl (HB) starch nanoparticles (SNPs) with varying molar substitution (MS) values.
• Evaluation of SNP thermoresponsivity in water using transmittance measurements.
• Characterization of hydrodynamic diameter (D_h) changes with temperature using dynamic light scattering.
• Assessment of the effects of salt concentration and alcohol-water mixtures on cloud point (T_c).

Main Results:

• Hydroxybutyl SNPs (HBSNPs) with MS values of 1.29-1.85 demonstrated thermoresponsivity with cloud points (T_c) between 33-52°C.
• T_c decreased with increasing MS in HBSNPs.
• HBSNP hydrodynamic diameter significantly increased above their T_c.
• Kosmotropic salts decreased T_c, while NaI (chaotropic salt) increased it.
• Alcohol-water mixtures lowered T_c, with more hydrophobic alcohols causing a greater decrease.

Conclusions:

• Thermoresponsive HBSNPs were successfully prepared for the first time.
• The thermoresponsive behavior of HBSNPs can be tuned by adjusting MS and environmental conditions.
• These findings open avenues for developing smart materials with applications in various fields.