Thermogelation Properties of ABA Triblock Copolymers of Poly(Ethylene Glycol) (B) and Copolyacrylates of Oligo(Ethylene Glycol)s (A) in Aqueous Solution

Abstract

Novel triblock copolymers with poly(ethylene glycol) (PEG) middle chain and random copolymers of di(ethylene glycol) ethyl ether acrylate (DEGA) and oligo(ethylene glycol) methyl ether acrylate (OEGA) as side blocks were synthesized by ATRP. The thermal gelation behavior of their 20 wt% aqueous solutions was studied as a function of the molecular characteristics of the triblock copolymers. The results showed that both association and gelation temperatures decreased with increasing polymerization degree and decreasing OEGA monomer content of the polyacrylate block. Also, both temperatures increased with PEG length at smaller MW of the PEG chain, and decreased for higher MW PEG. Rheometrical measurements showed that the length of the PEG block is the most important factor influencing elastic modulus and even structure of the hydrogels formed at 37°C.

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Keywords:

• ATRP
• Di(ethylene glycol) ethyl ether acrylate
• Oligo(ethylene glycol) methyl ether acrylate
• Poly(ethylene glycol)
• Thermal gelation
• Thermoresponsive hydrogels
• Triblock copolymers

Acknowledgment

The financial support of the National University Research Council in Romania, through the PN II - IDEAS grant no.389/2007, is gratefully acknowledged. Also, I. Negru acknowledges the financial support of the Human Resources Development Sectorial Operational Program 2007–2013 of the Romanian Ministry of Labor, Family, and Social Protection through the Financial Agreement POSDRU/88/1.5/S/61178.