مجله ایرانی پلیمر
سال:1381 | دوره: | شماره: |تعداد مقالات:4

Poly(arylenevinylene)s are considered to be promising candidates for electrical and/or optical materials. Most of these polymers are neither fusible nor soluble in common solvents, making it difficult to process them into shaped articles. The synthetic procedures have mostly involved the preparation of a precursor polymer which is processible, usually in solution, and which can then be converted into the desired poly(arylenevinylene); alternatively, these conjugated polymers can be rendered soluble and therefore processible in organic solvents by attaching large lipophilic groups to the arylenevinylene moiety. The precursor route involves producing a polymer in which the arylene units are connected by ethylene units. The saturated units contain a group which not only solubilizes the macromolecule and allows processing, but which can under suitable conditions also act as a leaving group, thus affording the saturated vinylene units of a fully conjugated polymer. In this article the synthesis of poly(hetero)arylene vinylenes via a soluble precursor polymers, characteristics, mechanism of polymerization and their application together with some properties are reviewed.

Since the discovery of insulin and establishment of its value in the treatment of diabetes mellitus, many investigators have explored the possibility of developing an effective method for its administration other than by injection. The reason is that the necessary injections of the hormone are not only inconvenient but also result in physiological complications as well. In this study, the possibility of an oral administration of insulin was investigated. A group of biodegradable polymers from polyglycol succinates family was synthesized by bulk polycondensation reaction of glycols with diethyl succinate. The polymers were purified and used for microencapsulation of insulin. The size and shape of microcapsules were studied with optical and electron scanning microscope. The rate of release of core material from the microcapsules was measured by a direct UV absorption method. It was found that pH of the environment, microcapsules wall thickness and the type of glycol used in the polymerizations are the most important factors on the controlled release.

4-(4"-Aminophenyl)-1,2,4-triazolidine-3,5-dione (1) was reacted with trimellitic anhydride (2) in refluxing DMF (N,N-dimethylformamide) and gave 4-(4"-N-trimellitylimidophenyl)-1,2,4,-triazolidine-3,5-dione (NTMPTD) (3) in high yield and purity. This compound was characterized by IR,1 H NMR and elemental analysis. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) were performed in DMSO in the presence of pyridine as a catalyst and lead to the formation of novel aliphatic polyureas. The polymerization reaction with tolylene-2,4-diisocyanate (TDI) gave novel aromatic polyurea. These novel polyureas have inherent viscosities in a range of 0.11-0.21 dLg-1 in DMF at 25 ° C. Some structural characterization and physical properties of these novel polymers are reported.

In this study chitin was extracted from shrimp's shell of Persian Gulf, using different methods and chitosan is derived from chitin as a microcrystalline powder, which is being named as Persian Gulf chitosan (PGC) with deacetylation degree of 86 % and the viscosity-average molecular weight (M v) of 3.57x105. The purpose of this experiment was to evaluate the effectiveness and safety of PGC as a hemostasis agent with surgical application. Results using PGC in sheep carotid punctured hole model showed significant reduction in manual compression time (p<0.009) of the carotid artery. Comparative results were found in sheep, wherein a created wound in the carotid artery could be sealed relatively quickly and easily. There were no significant differences in time length to hemostasis between heparinized and non-heparinized sheep. This work suggests that PGC is a safe and effective biopolymer to achieve hemostasis.