Degradation, hydrolytic spectroscopy

Fig. 32. Relation between the residual unsaturation ( ) IR-spectroscopy, (O) hydrolytic degradation resp. the titratable acid groups of microgels (a) and their EUP-content [132]. EUP(MA+HD),Mn 1640, c/t 67/33, EUP/S varied, W/M 20.

Deters, and Huang (129) describe the formation of graft copolymers of cellulose triacetate and vinyl chloride in vibratory mill treatments. Through hydrolytic degradation of the triacetate backbone, they isolated the polyvinyl chloride side chains and characterized them by infrared spectroscopy and cryoscopic molecular weight determination. The length of the side chains has been found to be between 15 and 30 vinyl chloride units. 

Reactions can be conveniently monitored by H NMR spectroscopy or UV/vis spectrophotometry, and when conducted in nonaqueous solvents proceed without detectable core degradation. In aqueous solution at neutral and basic pH values, ligand substitution seems to be the first step in hydrolytic core degradation (68, 69). Therefore, when these reactions are carried out in an aprotic solvent, or in an aprotic-aqueous solvent mixture. 

It is clear that hydrolytic attack of S. salivarius levan produces two structurally different degradation products, one that conforms to behavior in solution characteristic of spheres and the other characteristic of random coils. It should be mentioned that solution properties are greatly affected by the presence of even a few long branches but insensitive to many short branches. In this connection it was shown from 3c nMR spectroscopy that the spectra of the high vs. low molecular weight levan hydrolysates do not differ (27) suggesting perhaps the presence of short branches in the samples of... 

Vasanthan, N., Ly, O., 2009. Effect of microstructure on hydrolytic degradation studies of poly(L-lactic acid) by FTIR spectroscopy and differential scanning calorimetry. Polym. Degrad. Stabil. 94, 1364-1372. 

Taddei and co-workers [42] investigated the kinetics and mechanism of in vitro and in vivo degradation of Vicryl (lactide-glycolide copolymer) periodontal mesh, using Fourier-Transform Raman, attenuated total reflectance/Fourier-Transform-infrared (FT-IR) spectroscopy and DSC. A saline phosphate buffer and a sodium hydroxide solution were used as the aqueous media to study the hydrolytic in vitro degradation and the membrane implanted in vivo for four weeks. 

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