Polymer toxicity forms

The kinetics of thermal decomposition and depolymerisation of various polymers is discussed. The aim of the study was to find reaction conditions where different polymers can be separated from mixtures by decomposing them into their monomers or into pyrolysis products and where chlorine and/or nitrogen are eliminated from the polymers without forming toxic compounds. Data are given for PVC, PS, PE, and PR 13 refs. 

Perfluoro polyethers (Fomblin) (Krytox ) (3 x IO 8) If exposed to too much heat, decomposes to a gas rather than breaking down. Is resistant to oxidation and chemically resistant with few exceptions. No polymers are formed under energetic particle bombardment. Can be regenerated for reuse. Provides somewhat lower pumping speeds than other oils. High initial cost. Above 300 - 350°C, breaks down into aggressive and toxic compounds. To effectively remove it, chlorofluorocarbons must be used. 

Polymer 1 is designed to have nontoxic building blocks. The ultimate degradation products are expected to be 1,2-propylene glycol, phosphate, and ethanolamine, all with minimal toxicity profiles. The polymer readily forms complexes with plasmid DNA. A unique feature of this system is the capabihty of controlled release of plasmid from the polymer/DNA complexes, achieved as a result of polymer degradation. 

For gene delivery applications, cationic polymers that form complexes with nucleic acids through electrostatic interactions are often used as non-viral vectors that provide protection of DNA from enzyme degradation and facilitate cellular uptake. Monosaccharides or polysaccharides have been well studied for the production of low-toxicity gene delivery vectors. 

In an early process, THPC and urea were reacted together on the cotton fabric. Later, the THPC was replaced by the less toxic sulphate or hydroxide, which were applied as aqueous solutions to the fabric. This was then dried and exposed to ammonia when a highly insoluble polymer was formed within the cotton fibres. 

Inert matrices are manufactured with polymers that form an indigestible and insoluble skeleton after compression. These polymers must accomplish different requirements such as ability to form a porous and non-disintegrable net after compression, insolubility in the gastrointestinal fluids, compatibility with the drug and other excipients, and lack of toxicity [2]. Examples of materials that are used as inert matrix-forming polymers are metacrylate copolymers (Eudragit RS), ethyl cellulose, dibasic calcimn phosphate, polyvinylacetate (PVA), etc. 

Pure acrylonitrile boils at 78°. Acrylonitrile vapour is highly toxic it should therefore be handled with due caution and all operations with it should be conducted in a fume cupboard provided with an efficient draught. Acrylonitrile forms an azeotropic mixture with water, b.p. 70-5° (12-5 per cent, water). The commercial product may contain tte polymer it should be redistilled before use and the fraction b.p. 76 -5-78° collected separately as a colourless liquid. 

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