caa a22 4500 477127509 CHVBK 20180405111654.0 cr unu---uuuuu 170330e19970401xx s 000 0 eng 10.1023/A:1012199500072 doi (NATIONALLICENCE)springer-10.1023/A:1012199500072 Evaluation of a Statistical Model for the Formation of Poly [Acryloyl Hydroxyethyl Starch] Microspheres [Elektronische Daten] [L. Huang, R. Mehta, P. DeLuca] Purpose. To characterize the network structure of Poly (Acryloyl Hydroxyethyl Starch) (Ac-HES) microspheres and test the theoretical model and the hypothesis that the rate of swelling of microspheres is inversely related to the extent of crosslinking. Methods. Microspheres were prepared with varying degrees of derivatization (DD) and molar ratios (MR) and subjected to the characterization of matrix structure by dynamic and equilibrium swelling studies utilizing direct microscopic observation and the Flory-Rehner equation. The dependence of average molecular weight between crosslinking Mc, on DD and MR were compared to test the validity of the model. Results. Study of the dependence of Mc on the microspheres preparation parameters, DD and MR, showed that at constant MR, the Mc decreased with DD, while at constant DD, the Mc initially decreased with MR to a minimum, and then increased with MR, complying with the model prediction. Dynamic swelling of microspheres showed a monotonical increase to equilibrium size featured by two time variables, Tp and Teq, that were dependent on Mc; this permitted a conceptual view of the general structure of the Ac-HES microspheres. The Mc, which was more accurately determined by the weight method (as opposed to volume method), was independent of the size of microspheres although there was evidence of variation among particles within a batch. Conclusions. The results validated the model in describing the polymerization/crosslinking reaction of the Ac-HES microsphere system and suggested that Mc is the principal factor in controlling release. Plenum Publishing Corporation, 1997 Flory-Rehner model nationallicence dynamic and equilibrium swelling nationallicence molecular weight between crosslinks (Mc) nationallicence degree of derivatization(DD) nationallicence molar ratio (MR) nationallicence Huang L. 202, Her-Ping St., East District, 401, Taiwan, Taichung City, R.O.C aut Mehta R. ISIS Pharmaceuticals, 2292 Faraday Ave., 92008, Carlsbad, California aut DeLuca P. College of Pharmacy, University of Kentucky, 907 Rose Street, 40536-0082, Lexington, Kentucky aut Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/4(1997-04-01), 475-482 0724-8741 14:4<475 1997 14 11095 https://doi.org/10.1023/A:1012199500072 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1012199500072 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Huang L. 202, Her-Ping St., East District, 401, Taiwan, Taichung City, R.O.C aut NATIONALLICENCE 700 1- Mehta R. ISIS Pharmaceuticals, 2292 Faraday Ave., 92008, Carlsbad, California aut NATIONALLICENCE 700 1- DeLuca P. College of Pharmacy, University of Kentucky, 907 Rose Street, 40536-0082, Lexington, Kentucky aut NATIONALLICENCE 773 0- Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/4(1997-04-01), 475-482 0724-8741 14:4<475 1997 14 11095 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer