Intelligent ABC Triblock Copolymers PEO-PAA-PNIPAM: Synthesis, Self-assembly And Controlled Drug Delivery

Over the past 10 years, the intelligent polymer materials have attracted great interest as the new technology and the new functional materials. Intelligent polymers also called smart polymers, stimuli-responsive polymers or environment sensitive polymers, is the polymers which can feel the change of the environment, but also to take response measures to environmental changes. Molecular design and organic synthesis methods make polymeric materials have senior functions given by biology, such as ability of self-healing and self-value-added, ability of knowledge and identification, ability of stimuli-response and environment-response. Intelligent polymers research involves a number of fundamental researches, involving information, electronics, life sciences, space, marine science and other fields, many results have been applied in the high tech and high added industries and have become one of the important polymer development directions.In this paper, the pH response and temperature response of the intelligent triblock copolymer PEO-PAA-PNIPAM was synthesized by atom transfer radical polymerization (ATRP) and hydrolysis. First the macroinitiator PEO-Cl was synthesized by PEO andα-Chloropropanoic acid. Then, by twice ATRP, synthesize the diblock copolymers PEO-PtBA-Cl, and get the triblock copolymer PEO-PtBA-PNIPAM. At last, the final product PEO-PAA-PNIPAM was got by hydrolysis in trifluoroacetic acid. We use GPC, NMR and IR to systematically characterize each step of the molecular weight, molecular weight distribution and structure and identify them as the polymer of expected structures.Also we studied the self-assembly behaviors of the triblock copolymer PEO-PAA-PNIPAM. Using of the temperature-response of PNIPAM segment's characteristics, slowly increase the temperature, PNIPAM gradually shrinks to hydrophobic segment, becomes the formation of micelles, maintains the temperature, crosslinks PAA segments, then we can get the micelles of stable structure in room temperature. The spherical micelles, and have a narrow particle size distribution were characterized by dynamic laser light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (TEM).Finally, we studied the drug delivery behaviors of the embedding of this anti-cancer drug doxorubicin (DOX) micelles in a simulated human body environment. Under the three different conditions, in 37℃pH=4.0,37℃pH=7.4 and 25℃pH=7.4, We compared the release behavior of doxorubicin. The results show that the crosslinked micelles for controlled drug delivery has good stability, has a good prospect in the release drug delivery system.