synopsisStyrene was copolymerized in bulk with a number of esters of benzylidenecyanoacetic acid. The kinetic scheme of all pairs fitted the improved scheme of copolymerization, taking into account the effect of the penultimate unit. The Alfrey-Price Q and e values were calculated. Using the modified Taft equation, log ( l h ) = p*u* + SE,, it was found that the relative reactivities of the ester monomers toward the polystyryl radical were correlated by the polar substituent constants u* of the ester alkyl groups ( p * = 0.14) and not by their steric substituent constants E, (6 = 0.008). RbumQLe styrene a 6t6 copolymBris6 en masse avec certains esters de l'acide benzylidbnecyanoac6tique. Le schema cin6tique de toutes les paires est conforme au schema de copolym6risation am6lior6 qui tient compte de l'effet de l'unit6 p6nultihme. Les valeurs Q et e selon Alfrey-Price ont 6t6 calcul6es. Utilisant 1'6quation de Taft modifibe, log ( l h ) = p*u* + SE,, il a 6th trouv6 que les r6activit6s relatives des comonombres B l'bgard de l'attaque du radical polystyryle sont influencbs par les constantes des substituants polaires u* ( p * = 0.14) mais non pas par les constantes des substituants st6riques E,,(S = 0.008) des substituants alcoyl6s des esters. ZusammenfassungStyrol wurde in Substanz mit mehreren Ester der Beneylidencyanessigsaure copolymerisiert. Alle Paare entsprachen dem verbessertem Reaktionsschema der Copolymerisation, das den Einfluss der Vorletzten Gruppe berucksichtigt. Die Alfrey-Price Q und e Werte wurden berechnet. Bei Benutzung der modifizierten Taft Gleichung, log (l/rl) = p*u* + SE., wurde gefunden, dass die relativen Reaktivitaten der EsterMonomere gegen Polystyrolradikale von den polaren Substituentenkonstanten u* ( p * = 0.14), nicht aber von den sterischen Substituentenkonstanten E, (6 = 0.008) der Alkylgruppen der Ester abhiingen.

We report development of special macroporous semipermeable membranes and diffusion chambers made of polymerized 2-hydroxyethyl methacrylate (pHEMA), synthesized specifically to enclose living insulin-producing pancreatic islet cells for the treatment of diabetes. This material was selected to minimize the fibrotic encapsulation which has limited hybrid artificial pancreas efforts with other membranes, including Millipore and Nuclepore filters. The pore density and pore size distribution were dependent on the ratio of water to HEMA monomer and also on the crosslinker (EGDMA) concentration. A macroporous membrane resulted only when the ratio of water/HEMA monomer was greater than 50%. 125I-insulin permeability was studied in vitro. A technique is also described to fuse the membranes to form diffusion chambers used for implantation into diabetic rats.

SynopsisThe terpolymerizations of acrylonitrile, styrene, and seven esters of a-cyanocinnamic acid were investigated up to low conversions. Polymerizations, carried out in bulk at 7OoC, were initiated by free radicals. The relationships between monomer feed and terpolymer composition were determined on a triangular coordinate graph as proposed by Slocombe. In all cases, there exists an azeotropic line, connecting the binary azeotrope of the pair acrylonitrile-styrene and that of the various pairs of styrene with the esters of a-cyanocinnamic acid, yet no real ternary azeotrope was found.

Implantable, sustained release drug delivery devices offer benefits not obtained through oral ingestion or injection. These include delivery at a constant therapeutic rate, thus avoiding adverse intermittent and massive dose effects, as well as reliance upon patients taking their prescribed dosages. The drawbacks to their widespread acceptance have been their inability to maintain a zero-order release rate over an extended period of time and poor biocompatibility. Devices capable of satisfying these requirements have been developed and tested extensively for in vitro release of the narcotic antagonist cyclazocine. By using implant models prepared from Hydron, a hydrophilic polymer known to exhibit excellent tissue compatibility, we have found that the release rate could be precisely regulated by proper geometry, copolymer composition, concentration of ionogenic groups and cross-link density. Devices in such varied forms as capusles, barrier-film coated tablets and bulk polymerized rods have been tested in vitro for periods approaching 1 year.

Acrylonitrile was copolymerized in bulk with cinnamonitrile (I), ethyl benzylidenecyanoacetate (II), and benzylidenemalononitrile (III) by radical initiation up to low conversions. The conventional scheme of copolymerization fitted all the three copolymer pairs.