Cellulose acetate microspheres with surface hydroxyl gps. - by dispersing soln. of cellulose acetate in volatile solvent, in aq. medium, then evaporating and hydrolysing with aq. sodium hydroxide soln.

摘要

Hydroxyl gp.-contg. cellulose acetate (CA) microspheres (I) consist of 0.1-50 micron spherical particles with a compact CA core and a mainly cellulosic surface layer making up 1-50% of the total wt. of the particle, with sedimentation vol. 0.5-4 ml/g on swelling in water and porosity below 0.4 ml/g for meso- and macro-pores. Also claimed is a process for the prodn. of (I), by dissolving CA and opt. other additives in a volatile, water-immiscible solvent, dispersing the soln. in an aq. medium contg. suitable protective colloids and/or emulsifiers, then removing the solvent in evapn. and hydrolysing the microspheres; hydrolysis is carried out with 0.05-1N aq. NaOH soln. for 5-360 mins. at 20-50degC (during or after evapn. of solvent), and is stopped by neutralising with mineral acid or AcOH or by washing out the alkali. USE/ADVANTAGE - (I) are useful for the prodn. of special sepn. and carrier materials for chromatographic and diagnostic applications in biotechnology, biochemistry and medicine. The invention provides OH-contg. CA microspheres with desirable properties such as sphericity, small particle size and porosity, in which the OH gps. are largely localised at the surface of the particles; (I) are produced by a simple, economical proces