Poly(dichlorophosphazene) was prepared by melt ring-opening polymerization of the hexachlorocyclotriphosphazene. Poly[bis(2-hydroxyethyl-methacrylate)-phosphazene] and poly[(2-hydroxyethyl-methacrylate)-graft-poly(lactic-acid)-phosphazene] were obtained by nucleophilic condensation reactions at different concentrations of the substituents. The properties of the synthesized copolymers were assessed by FTIR, 1H-NMR and 31P-NMR, thermal analysis (DSC-TGA), and electron microscopy (SEM). The copolymers have a block structure and show two 's below room temperature. They are stable up to a temperature of 100°C. The type of the substituents attached to the PZ backbone determines the morphology of the polymers. 1. Introduction Polyesters, polyorthoesters, polyanhydrides, poly(R-amino acids), and polyphosphazenes are degradable polymers that have been investigated for a variety of biomedical applications such as sutures, drug delivery systems, and scaffolds for tissue engineering [1]. Useful properties can be obtained by blending two different polymers. However, compatible polymer blends require strong molecular interactions between polymer chains [2]. Poly(organophosphazenes) offer an appealing platform for the design and synthesis of novel biodegradable polymers as well as critical advantages for the design of biologically functional macromolecules with a broad structural diversity [3], high functional density, and tailored biodegradability [4]. These polymers are of scientific and technological concern since the first work of synthesis reported by Allcock et al. [5, 6]. Polyphosphazenes (PZs) posses special characteristics, including flame-retardant properties, high resistance to oil and solvents, and feasibility for tailored properties according to the choice of organic, inorganic, or organometallic side groups [7]. As biomaterials they have inherent advantages, due to their biocompatibility and fast degradation rate. In addition, degradation residues, phosphate, ammonia, and side groups are either nontoxic when they are present in small quantities or are easily metabolized by the human body [8, 9]. Polyphosphazenes are hybrid polymers with a flexible inorganic backbone of alternating phosphorus and nitrogen atoms and organic side groups. Their composition vary from 3 to 10,000 (–N=P–) repetitive units having two substituents (–R) attached to the phosphorus atom [7]. Polyphosphazenes are synthesized by reactions with alkoxides, aryloxides, or amines from a highly reactive macromolecular intermediate, poly(dichlorophosphazene), which is prepared by thermal
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