Abstract: Novel composite materials and their methods of preparation comprising a crosslinked biodegradable polymer and non-crosslinked biodegradable polymers are disclosed. The composite materials can be formed into injectable compositions comprising composite microparticles or microspheres. The non-crosslinked biodegradable polymer in the composite material is synthesized or precipitated in situ inside the particle. The non-crosslinked biodegradable polymer in the composite may be liquid, low melting solid or polymer with thermosensitive or pH sensitive gelation properties. Also disclosed are injectable compositions comprising microparticles or microspheres for controlled drug delivery wherein such particles are delivered using organic solvents. Also disclosed are methods and compositions for making two or more layered particles for medical and industrial use.