No abstract

Diblock polystyrene-6(oc/e-poly(methacrylic acid) polymers have been synthesized using anionic polymerization techniques incorporating an average of one naphthalene per polymer at either the beginning of the polystyrene block or at the junction between the polystyrene and poly(methacrylic acid) blocks. These polymers have been shown in earlier work to form stable micelles in solvent mixtures from 80:20 dioxane/H20 to pure water. In the present paper we have examined the ability of these polymers to adsorb on polystyrene films and have used photophysical techniques to deduce the exposure of the naphthalene group to the aqueous phase. Scanning electron microscopy images demonstrate that the intact micelle adsorbs onto the polystyrene surface and can achieve a nearly close-packed monolayer coverage. The micelles adhere tenaciously to the polystyrene film and lower the contact angle of water from ca. 90°for untreated polystyrene to 30-40°after surface adsorption. The naphthalene groups at the polystyrenepoly(methacrylic acid) junction are partially exposed to the aqueous phase while the naphthalene at the poly(styrene) end is totally protected.

A hydrolyzable crosslinker (N,O-dimethacryloylhydroxylamine (MANHOMA)) was synthesized by a modified method and was characterized using 1 H-NMR, FTIR, and melting point determination. Naltrexone-loaded nanoparticles were prepared by copolymerization of poly(ethylene glycol)1000 monomethyl ether mono methacrylate (PEO-MA), methyl methacrylate (MMA) and N,O-dimethacryloylhydroxylamine (MANHOMA) in 0.4% poly(vinyl alcohol) aqueous solution. The nanoparticles were characterized by FTIR, particle size determination and transmission electron microscope (TEM). The TEM photomicrographs of the nanoparticles show a crosslinked core surrounded by a ring formed by the polyethylene glycol tail of PEO-MA. The loading efficiency of the nanoparticles and in vitro drug availability from the nanoparticles were investigated. The naltrexone-loaded hydrolyzable crosslinked nanoparticles were able to sustain the release of naltrexone for different periods of time, depending on the monomer feed composition.

Polypyrrole/crosslinked cellulose conductive composite films were prepared by vapor-phase polymerization of pyrrole on the silicon crosslinked cellulose network using anhydrous ferric chloride as oxidant. The properties of the composite film depend on their synthetic conditions such as the amount of ferric chloride and tetraethyl orthosilicate crosslinker, the reaction time, the solvent, etc. Interestingly, it was found that the conductivity was strongly affected by the nature of the solvents and their amount in pyrrole solution. When the weight ratio of methanol/pyrrole is 1 : 1, the conductivity was as high as 1.1 S/cm, increased by two orders of magnitude compared to that without solvent, and the mechanical properties was good.

No abstract