Polyanhydrides polymer blends

The physical and mechanical properties of polyanhydrides can be altered by modification of the polymer structure with a minor change in the polymer composition. Several such modifications include the formation of polymer blends, branched and crosslinked polymers, partial hydrogenation and reaction with epoxides. 

Biodegradable polymer blends of polyanhydrides and polyesters have been used as drug carriers [59], Polyflactic acid) (PLA), polyfhydroxybutyrate) (PHB), and poly(caprolactone) (PCL), of 2000 and 50000 molecular weights were mixed with poly(sebacic anhydride) (PSA), and the properties of these mixtures were studied. Mixtures of PHB and low molecular weight PLA or PCL formed uniform blends with various amounts of PSA. These blends possess different physical and mechanical properties compared to the parent polymers. The release rate of drugs from these polymeric blends increases with the increase in the content of the rapidly degrading component, PSA. 

The properties of polyanhydrides ean be modified by ehanging polymer composition and structure. This is obtained by realizing copolymers, polymer blends, erosslinking between ehains, partial hydrogenation and reaction with epoxides. Low moleeular weight PLA, PHB and PCL are miscible with polyanhydrides whereas high moleeular weight polyesters are not. 

The physical and mechanical properties of polyanhydrides can be altered by minor modifications. Biodegradable polymer blends of polyanhydrides and polyesters have been investigated as dmg carriers (Leong et al., 1984). A polymeric blend of poly (trimethylene carbonate) (PTMC) with poly(adipic anhydride) (PAA) and the matrix of PTMC—PAA blend was found to be biocompatible in vitro and in vivo experiments as well as a promising candidate for controlled drug delivery erosion with tuneable erosion rate achieved by varying the proportion of PTMC and PAA (Edlund and... 

Polyanhydrides Polyanhydrides have a hydrophobic backbone with a hydrolytically labile anhydride linkage. These polymers widely vary in chemical composition and include aliphatic, aromatic, and fatty acid-based polyanhydrides. The rate of degradation depends on the chemical composition of the polymer. In general, aliphatic polyanhydrides degrade more rapidly than the aromatic polymer. Hence, copolymer blends with varying ratios of aliphatic-to-aromatic polyanhydrides can be synthesized to suit specific applications. 

Kipper, M.J. Seifert, S. Thiyagarajan, P. Narasimhan, B. Understanding polyanhydride blend phase behavior using scattering, microscopy, and molecular simulations. Polymer 2004, 45 (10), 3329-3340. 

Bhardwaj and Mohanty [8] proposed and demonstrated a new industrially relevant methodology to develop a polylactide (PLA)-based nano blend having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyper branched polymer (HBP) was in situ cross-linked with a polyanhydride (PA) in the PLA matrix during melt processing. There was formation of new HBP-based cross-linked particles in the PLA matrix. TEM and AFM revealed the sea-island morphology of... 

---