Heteroarm Star-Shaped Poly (N-isopropylacryamide-co-itaconic acid) Copolymer Prepared by Glucose Core as ATRP Initiator

Abstract

Star-shaped temperature- and pH-sensitive poly (N-isopropylacryamide-co-itaconic acid) copolymer is synthesized by atom transfer radical polymerization (ATRP) using 1,2,3,4,6-penta-O-Isobutyrylbromide-α-D-glucose as 5-Arm ATRP Initiator. For ATRP of itaconic acid (IA), carboxylic groups of IA are protected via silylation by hexamethyldisilazane (HMDS) using Fe₃O₄ as a magnetic catalyst. The polymerization is carried out in 2-propanol/toluene 50:50 (v/v) mixed solvent at 90°C. Structure of copolymers is studied with FT-IR, ¹H NMR, glass transition temperature (Tg), and scanning electron microscopy (SEM). Results of temperature, pH, and percentage variation on polymer structure and the effects on lower critical solution temperature (LCST), which is investigated with potentiometery and conductometry, show that LCST of copolymer is around body temperature and demonstrate the ability of this polymer in the design of controlled drug delivery systems. According to the obtained results from naltrexone release, the investigated star-shaped copolymer may have potential applications in the controlled release of drugs.

Keywords:

• ATRP
• drug delivery
• LCST
• silylated IA
• star-shaped copolymer
• thermo- and pH-sensitive copolymer

Notes

IP_P = potentiometric titration inflection points; IP_C = conductometric titration inflection points.

FIA (mol%) = IA content in the feed; FIA_P (mol%) = IA content obtained from conductometry; FIA_c (mol%) = IA content obtained from potentiometry.