Abstract: The invention relates to spherical particles formed by polymer chains containing approximately from 30 to 10000 monomer units derived from monocyclic polycyclic alkene polymerization, wherein at least one monomer unit is substituted by an R chain including ethylene polyoxide which is optionally covalently linked to the polymer units through a hydrolyzable bridge and substituted by a reactive function, optionally engaged in a link with an active principle or a biological molecule such as protein, wherein the chain R is covalently linked to the monomer units. The use of the inventive spherical particles for preparing pharmaceutical and cosmetic compositions or surface coatings is also disclosed.