The invention concerns novel biodegradable polyaminoacid materials, useful in particular for vectoring active principles(s). The invention also concerns novel pharmaceutical, cosmetic dietetic or phytosanitary compositions based on said polyaminoacids. The invention aims at providing a novel polymer raw material, capable of being used for vectoring active principles and enabling optimal fulfillment of all specified requirements: biocompatibility, biodegradability, easy and inexpensive transformation into particles vectoring active principles, said particles being themselves capable of forming colloidal suspensions, of being easily associated with numerous active principles, and of releasing said active principles in vivo. Therefor, the present invention concerns first of all amphiphilic polyaminoacids comprising aspartic acid units and/or glutamic acid units, characterized in that at least part of said units carry grafts, including at least one alphα-tocopherol motif, for example (polyglutamate or polyaspartate grafted with alphα-tocopherol of synthetic or natural origin).