Poly polydispersity index

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

Hence, cation-radical copolymerization leads to the formation of a polymer having a lower molecular weight and polydispersity index than the polymer got by cation-radical polymerization— homocyclobutanation. Nevertheless, copolymerization occnrs nnder very mild conditions and is regio-and stereospecihc (Bauld et al. 1998a). This reaction appears to occnr by a step-growth mechanism, rather than the more efficient cation-radical chain mechanism proposed for poly(cyclobutanation). As the authors concluded, the apparent suppression of the chain mechanism is viewed as an inherent problem with the copolymerization format of cation-radical Diels-Alder polymerization. ... 

The polydispersity of dendritic molecules, expressed in the form of their poly-dispersity index (PDI), is directly related to their structural perfection. The PDI is a measure of molecular weight distribution. 

Fig. 1 Fractionation of poly(vinylchlorides) using HPLC/GPC — Polyscience PVC VHMW Aldrich PVC solid line experimental Occidental Chemical Co. Suspension-polymerized PVC PD = polydispersity index = 2 (random distribution).

In a 250 ml round bottom flask poly(azidomethyloxirane) (19.62 g) and the Step 1 product (6.63 g) were dissolved in 80 ml of CH2CI2 the solution concentrated sufficiently for the solution to become cloudy. This cloudy solution was then treated with 0.12 ml of dibutyltin dilaurate and toluene-2,4-diisocyanate (3.11 g). After 4 hours, butane-1,4-diol (0.805 g) was added, causing the solution to become steadily more viscous after another 18 hours, the solution was too viscous to stir. The mixture was then diluted with 50 ml of CH2CI2, precipitated, and the product was isolated having a Mj, of 28,440 daltons, M of 219,500, and a polydispersity index of 7.7. 

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