Characterization of Polyanhydrides

Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy ( H NMR) have beeome standards for verifying the ehemistry of polyanhydrides. The reader is referred to the synthesis literature in the previous section for spectra of specific polymers. The FTIR speetrum for PSA is shown in Fig. 2. In FTIR the absorption 

The analysis of NMR spectra of aliphatic and aromatic poly anhydrides has been reported by Ron et al. (1991), and McCann et al. (1999) and Shen et al. (2002), and C NMR has been reported by Heatley et al. (1998). In NMR, the aliphatic protons have chemical shifts between 1 and 2 ppm, unless they are adjacent to electron withdrawing groups. Aliphatic protons appear at about 2.45 ppm when a to an anhydride bond and can be shifted even further when adjacent to ether oxygens. Aromatic protons typically appear with chemical shifts between 6.5 and 8.5 ppm and are also shifted up by association with anhydride bonds. The sequence distribution of copolymers can be assessed, for example in P(CPH-SA), by discerning the difference between protons adjacent to CPH-CPH bonds, CPH-SA bonds, and SA SA bonds (Shen et al., 2002). FTIR and NMR spectra for many of the polymers mentioned in Section II can be found in their respective references. 

Several of the synthetic efforts outlined in Section II were motivated partially by the necessity of increasing the processability of polyanhydrides. Solubilities of the 20 80 copolymers of P(CPP-SA) and P(FAD-SA) are compared by Domb and Maniar (1993). They reported improved solubility of the later over former in several organic solvents including (in order of decreasing solubihty) THF, 2-butanone, 4-methyl-2-pentanone, acetone, and ethyl acetate. 

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Dang, W. Daviau, T. Brem, H. Morphological characterization of polyanhydride biodegradable... 

A major part of this chapter will review recent developments in the chemistry and properties of polyanhydrides, which includes new synthetic methods, new polymeric structures, and in depth characterization of polyanhydrides. The degradation and drug release properties and applications that were not reviewed previously are included. A review article by the same authors concentrating on polyanhydride applications and toxicity is in preparation [6]. 

Septicin antibacterial implant for the treatment of chronic bone infections have been developed [21-24]. The multidisciplinary concept of polymeric implants has expanded to include research on the chemistry and characterization of polymers, experimental and theoretical polymer degradation and drug release, toxicology and metabolism, and research in specific fields of applications such as cancer, proteins and hormones delivery, infectious diseases, and brain disorders. This chapter concentrates on the chemistry and characterization of polyanhydrides with a brief description on recent applications of polyanhydrides. 

In the past decade, extensive research has been carried out on the characterization of polyanhydrides. This section will describe the methods used for the characterization of polyanhydrides and data obtained about their chemical composition and structure, crystallinity and thermal properties, mechanical properties, and thermodynamic and hydrolytic stability. 

Dang, W., Daviau, T., Brem, H., 1996. Morphological characterization of polyanhydride biodegradahle implant Gliadel during in vitro and in vivo erosion using scanning electron microscopy. Pharmaceutical Research 13, 683—691. 

The synthesis of poly(anhydride-co-amide)s (Table VII) of various chemistries was pursued by Hartmann and Schulz (1989) as a means of improving biocompatibility and extending the degradation times of polyanhydrides. This work also contains calorimetry data on the thermal transitions and spectroscopic characterization. 

B. Characterization of Thermal Properties, Crystallinity, and Phase Behavior of Polyanhydrides... 

It is important to characterize the thermal properties of polyanhydrides that are proposed for drug delivery applications, as changes in crystallinity... 

To understand the properties that make polyanhy-drides suitable drug carriers, their chemical, physical, and thermal behavior need to be characterized. This section discusses the methods to determine the chemical structure and composition, the molecular weight, the thermal properties, the phase behavior, the stability, and the erosion mechanism of polyanhydrides. 

Jiang, H.L. Zhu, K.J. Preparation, characterization and degradation characteristics of polyanhydrides containing poly(ethylene glycol). Polym. Int. 1999, 48, 47-52. 

Torres, M.P. Vogel, B.M. Narasimhan, B. Mallapragada, S.K. Synthesis and characterization of novel polyanhydrides with tailored erosion mechanisms. J. Biomed. Mater. Res. Submitted. 

McCann, D.L. Heatley, F. D Emanuele, A. Characterization of chemical structure and morphology of eroding polyanhydride copolymers by liquid-state and solid-state IH n.m.r. Polymer 1999, 40 (8), 2151-2162. 

Mathiowitz, E. Ron, E. Mathiowitz, G. Amato, C. Langer, R. Morphological characterization of bioerodible polymers. 1. Crystallinity of polyanhydride copolymers. Macromolecules 1990, 23, 3212-3218. 

Su Q et al (2010) Preparation and characterization of biodegradable electrospun polyanhydride nano/microfibers. J Nanosci Nanotechnol 10(10) 6369-6375... 

Mathiowitz, E., Amato, C., Dor, P., Langer, R 1990a. Polyanhydride microspheres 3. Morphology and characterization of systems made hy solvent removal. Polymer 31,... 

Sun, L., Zhou, S., Wang, W., Su, Q., Li, X., Weng, J., 2009. Preparation and characterization of protein-loaded polyanhydride mictospheres. Journal of Materials Science Materials in Medicine 20, 2035-2042. 

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