Poly(methacrylic acid-g-ethylene glycol) (P(MAA-g-EG)) has been studied extensively in our laboratory due to its extremely promising applications in the biomedical and pharmaceutical fields. It exhibits pH-responsive interpolymer complexes that make it a promising candidate as an oral carrier for peptide and protein drug. We have developed a photoinitiated free-radical precipitation polymerization method to produce P(MAA-g-EG) nanospheres with relatively narrow size distributions. The influence of various reaction parameters, such as total monomer concentration in water, comonomer molar feed ratios, cross-linking agent concentration, and polymerization time, on the particle size and size distribution was investigated. P(MAA-g-EG) nanospheres with a relatively narrow size distribution could be produced in the size range 150-650 nm depending on the monomer concentration and comonomer molar feed ratio. The P(MAA-g-EG) nanospheres exhibited a pH-responsive swelling behavior. Increasing the concentration of the cross-linking agent during polymerization produced P(MAA-g-EG) nanospheres that swelled to a lesser degree. The morphology of the P(MAA-g-EG) nanospheres was investigated using cryogenic scanning electron microscopy.
Phase inversion from durene/naphthalene, durene/tmpdo, and durene/hexadecanol binary solvent/nonsolvent systems produced well interconnected, radiographically homogeneous, open-celled poly (4-methyl-l-pentene) or pmp foams. These foams ranged in density from 5 to 50 mg/cm'. Foam homogeneity and casting efficiency were dependent on casting scheme, durene quality, solvent-to-nonsolvent ratio, and quench temperature. Foam density tracked linearly with dissolved-polymer content. Homogeneous, ultralow-density (5 to 6 mg/cm') foams were produced by using a 49/51 durene/naphthalene solvent eutectic. Foam hardness or firmness tracked somewhat linearly with foam density. Foams with densities above 20 mg/cmVere quite firm. Foams with densities below 6 mg/cm' were too fragile to handle without damage.
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