Pluronic-PAA

Another area in which smart hydrogels are likely to find application is the development of more efficient drug delivery systems. One material that has showed promise in this held is called Pluronic-PAA. Its trade name is Smart Hydrogel . The material is a mixture of two polymers, one of which is poly(acrylic acid) (PAA), which attaches readily to other biological materials and is responsive to changes in pH. The other polymer is a copolymer of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO). This copolymer belongs to a family of polymers known by the trade name of Pluronic polymers. 

Poly( ethylene oxide)-block-poly (propylene oxide)-hZock-poly(ethylene oxide)-g-poly(acrylic acid) (PEO-fc-PPO-fc-PEO-g-PAA, Pluronic-PAA) graft copolymers were synthesized by free radical grafting copolymerization of acrylic acid monomers onto PEO-h-PPO-h-PEO (Pluronic F127) and the aqueous solution properties were characterized by Bromberg [133, 134]. Chiu et al. [135] reported on the micellization of (non-ionic) poly(stearyl methacrylate)-gra/f-poly(ethylene glycol) graft copolymers. 

Stable W/C macroemulsions for either liquid or supercritical CO2 have been formed with the surfactants (PFPE 000 )2 Mn2+ (13), PFPE COO-NH4 " (672-7500 MW) (9), and block copolymer pluronic surfactants composed of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) (51), PDMS and poly(acrylic acid) (PAA), or poly(methacrylic acid) and PDMS and PEO (2). The emulsions may be formed by shear through a 130 gm capillary or commercial homogenizer. The ratio of water to CO2 has been varied from 9 1 to 1 9 with less than 1 wt % surfactant. W/C microemulsions, on the other hand, contain less than 5 wt % water for this level of surfactant owing to the much higher interfacial area. 

Stable double emulsions, based on various block copolymers of polyethylene oxides and polypropylene oxides known as Pluronies, have been used. In a recent example. Cole and Whateley (84) have used complexes of Pluronic F127 PAA (polyaerylie aeid) in the internal aqueous phase. In the oil phase, Span 80 and Pluronie LlOl (5 wt %) were used. The outer interfaee was stabilized by xanthan gum (0.25 wt %) and Tween 80 (1 wt %). Theophylline and I-insulin (iodinated insulin) were ineorporated in the internal aqueous phase of the stabilized multiple emulsion, and the release rates were studied. The release rates were found to be related to the droplet sizes of the emulsion whieh were dependent on the partiele size of the pluronie F127 PAA eomplex in the internal aqueous phase and the type of the lipophilie surfaetant in the oil phase. The authors have used the eomplex between the poloxamer surfactant and PAA that occurred at pH 2 and at low molar ratio as a barrier for the release of active matter from the inner to the outer phase. 

Another example of pH-responsive polymer synthesized by ATRP was the PAA and Pluronic P85 block copolymers (P85PAA) prepared by Tian... 

Choo ESG, Yu B, Xue J. Synthesis of poly(acryhc acid) (PAA) modified pluronic P123 copolymers for pH-stimulated release of doxorubicin. J Colloid Interface Sci 2011 358 462—70. 

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