Glycidyl azide-r-(3,3-bis(azidomethyl)oxetane) copolymers were synthesized by cationic copolymerization of epichlorohydrin and 3,3-bis(bromomethyl)oxetane, using butane-1,4-diol as initiator and boron trifluoride etherate as catalyst, followed by azidation of the halogenated copolymer. The main objective of this work is the preparation of an amorphous polymer with energetic content higher than that of the well known glycidyl azide homopolymer. The effect of experimental conditions, like i.e. the rate of monomer feeding, on the final molecular weight and functionality of the copolymer has also been investigated. The obtained copolymers were extensively characterized to determine their composition and thermal stability. The heat of reaction for the polymerisation of the halogenated key precursors has also been measured.
Azidated oxetanic polymers such as poly(3‐azidomethyl‐3‐methyl oxetane), are under investigation as “energetic” binder to be used as an alternative to polybutadiene in solid rocket propellants. The classic synthetic route for the production of the polymer is through an azidated monomer where the N3− functionality has been previously introduced by nucleophilic displacement of a suitable, usually a halogen, leaving group. However, this could involve critical steps with manipulation of a highly unstable liquid monomer. Here it is shown that the azidation can be performed as the final step of the preparation by substitution of the tosyl group in a preformed polymer. The procedure assures good yield and purity of the product and satisfactory rate of reaction, being the energetic functionality always kept in a safe form, which shows low shock and friction sensitivity. Poly(3‐azidomethyl‐3‐methyl oxetane) was prepared by azidation of poly(3‐tosyloxymethyl‐3‐methyl oxetane) in dimethylsulfoxide, testing several operating conditions. Moreover, hypothesizing a second order kinetics, the rate constant and the activation energy for the azidation step have been estimated.
SummaryTwo cases of congenital combined deficiency of factor VIII (antihaemophilic globulin) and factor V (proaccelerin) in 2 sibilings (a female and a male) born of non-consanguineous parents are reported.Mild isolate defect of factor V was demonstrated in the mother and in 2 maternal aunts, while pure factor VIII deficiency was found in a male relative on the maternal side.Infusion of normal fresh plasma lead in both cases to a parallel rise of both factors, while infusion of haemophilic plasma lead to a rise of factor V only, thus excluding the presence in the haemophilic plasma of a common precursor to both factors.The genetic study of the family seems to suggest that the two defects are inherited according to different patterns, two genes being responsible for the two defects. Factor V deficiency seems inherited according to an autosomal incompletely dominant type of heredity, while factor VIII deficiency is due to a sex-linked mutant gene.Genie interaction, inversion of the dominance or early inactivation of the normal X-chromosome in a carrier are the possible explanations for the severe factor VIII deficiency in the proposita.
Poly(3-azidomethyl-3-methyloxetane) and its copolymers with 3,3-bis(azidomethyl)oxetane were synthesized by cationic polymerization from 3-tosyloxymethyl-3-methyl oxetane and 3,3-bis(bromomethyl)oxetane, using a polyol as initiator and boron trifluoride complex as catalyst, followed by azidation. The final objective is the synthesis of an energetic binder to be used for rocket propellants and therefore the effects of different initiator/catalyst systems on important properties, like, i.e., the molecular weight distribution and the functionality of the polymer, were investigated. It was found that, even though both the operating conditions and the catalytic system were chosen in order to grant the living character of the polymerization, the latter seems to be prevalently driven by an "active chain end" mechanism. In particular, this may lead to the undesired formation of a small quantity of oligomers and to the presence of non-hydroxylic chain-end functionalities. Nevertheless, the average number of OH groups can be strictly controlled when boron trifluoride tetrahydrofuranate is used as catalyst.
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