A novel of amphiphilic diblock copolymer (P(IBA-co-DMAEMA)-b-PHPA)

which composed of poly(isobutyl acrylate-co-2-(N

N-dimethylamino)ethyl methacrylate) random copolymer block and poly(2-hydroxypropyl acrylate)

was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization

and its structure and composition were confirmed by gel permeation chromatography (GPC)

1H nuclear magnetic resonance (1H-NMR) spectroscopy and FTIR spectroscopy.This copolymer could self-assemble into stable polymeric micelles.The critical micelle concentration values of the self-assembled micelles were about 2.1 mg/L in distilled water relying on fluorescent probe technique.The results measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the self-assembled P(IBA-co-DMAEMA)-b-PHPA micelles exhibited spherical core-shell structure with mean hydrodynamic diameter around 110~136 nm and uniform and narrow size distribution in aqueous media.The model drug folic acid (FA) was loaded into the micelles as drug carrier material and the in vitro drug release behavior was investigated at physiological conditions.We found that the FA-loaded content and the entrapment efficiency reached up to 38% and 76%

respectively.In phosphate buffer solution(PBS)at ionic strength I=0.15 kg/mol

temperatures T=37℃

and different pH=2.0

7.4and 9.2

in vitro release rates of folic acid (FA) from polymeric micelles were all relatively faster within 40 h

and increased with pH value increase.Followed by slow release

the largest accumulation release percentage was 36%

61% and 80%

respectively.Thus

the polymeric micelles are expected to be a novel type of carrier material with pH-responsive and high drug loading capacity for drug delivery.