Polymerization ethylenimine

The CROP of N-tetrahydropyranylazlridine results in the tetrahydropyran-protected linear poly(ethylenimine) and, thus, provides straightforward access to linear poly(ethylenimine) by acidic removal of the tetrahydropy-ran groups (Scheme 8.23) [136]. As discussed previously, linear poly(ethylenimine) cannot be prepared by simply polymerizing ethylenimine because of transfer reactions resulting in branched polymers. Poly(ethylenimine)s with polymerizable methacrylate side groups have been reported based on the CROP of 2-(l-aziridinyl)ethyl methacrylate (Scheme 8.23) [137]. Subsequent radical polymerization of the methacrylate moieties results in densely crosslinked... 

Ring-opening polymerization of 2-methyl-2-oxazoline produces poly( V-acetyl-ethylenimine) (Scheme 2) [24-27], The resulting polymer can be regarded as a... 

Aminoethyl-8 has an advantage over ethylenimine modification (see next section), due to the potential polymerization of ethylenimine in aqueous solutions. Such polymers are highly cationic and may nonspecifically block the protein. The specificity of Aminoethyl-8 for sulfhydryls makes it an optimum choice for modification. 

Ethylenimine is strongly caustic and burns the skin. Inhalation of the vapor causes acute inflammation of the eyes, nose, and throat, with symptoms resembling those of bronchitis. After two or three days, the irritation subsides and the tissues return to normal, without suffering any apparent permanent injury. Continued exposure to the vapor may cause an individual to acquire an extreme sensitivity to it. Ethylenimine is also very inflammable and polymerizes with explosive violence under certain conditions. ... 

An interesting polymer constrained to a relatively compact conformation is polyethylenimine (PEI), which can be prepared by suitable polymerization of ethylenimine (Fig. 2) to give a highly branched rather than a linear macromolecule.19 The structure of a segment of this polymer is shown in Fig. 2. Approximately 25% of its nitrogens are primary amines, 50% secondary, and 25% tertiary.19 The branching of the polymer may be represented schematically as shown in Fig. 3. 

Formation of ethylenimine by the pyrolysis of 2-oxazolidone has been claimed, 88 -3J The evidence is based on the isolation of polymeric products and is of doubtful validity. 

The interpretation of the mechanism of polymerization is supported by studies of the kinetics of the reaction and the determination of the structure of low molecular weight polymers.1 2 For example, from the polymerization of ethylenimine, products have been identified corresponding to Eq. (eh) where n - 1, 2 and 3. ... 

If the imine formation is conducted in a flow tube, residence times of 4 to 10 seconds can be used to suppress secondary reactions such as the polymerization of ethylenimine. The imine selectivity then increases to 80% to 85% (based on MEA)46. 

In the literature, linear polymers are referred to as poly(iminoethylene), and branched polymers as poly(ethylenimine), since the latter derive from the ring-opening polymerization of ethylenimine. In this review, both polymers will be referred to as PEI. Mention will be made, however, to their structure whenever opportune. 

A variety of mono-, di-, tetra-, and polydendron PAMAMs have been synthesized from simple amines as well as linear polyamine cores [2, 83, 124]. Linear poly(ethylenimines) with core multiplicities (Nc of ca. 300-400) have been shown to produce high-aspect ratio, rod-like dendrimers at generation 3 or 4 [2]. Their length is determined by the degree of polymerization (n) of the initiator core and their diameter is derived from the number of generations (see Scheme 3). 

Flammable liquid flash point (closed cup) -11°C (12°F) vapor pressure 160 torr at 20°C (68°F) vapor density 1.48 (air = 1) the vapor is heavier than air and can travel a considerable distance to a source of ignition and flash back autoignition temperature 322°C (612°F) fire-extinguishing agent dry chemical or alcohol foam firefighting should be done from an explosion-resistant area use water to flush and dilute any spill and to keep Are-exposed containers cool. Ethylenimine may polymerize under fire conditions. The reaction is exothermic, which may cause violent rupture of the container. 

Ethylenimine vapors form explosive mixtures with air within a wide range, 3.3-46.0% by volume in air. Undiluted ethylenimine can undergo violent polymerization in the presence of an acid. Reaction with chlorine or hypochlorite forms 1-chloroethyleneimine, which is an explosive compound. Its reaction with concentrated mineral acids is vigorous and with strong oxidizers is vigorous to violent. 

Subsequent hydrolysis of the formamide groups resulted in the amino-functionalized poly(ethylenimine) as depicted in Scheme 8.23. A final example of a functional poly(aziridine) is based on the polymerization of the bicyclic l-aza-[l,3,0]-bicyclohexane monomer resulting in a chiral polymer with a cyclic tertiary amine in the backbone (Scheme 8.23) [139, 140]. 

Besides the direct polymerization of N-substituted cyclic amines, PAAIs can also be prepared by the allgrlation of PHAIs (Scheme 2.13a), as was first reported by Tanaka et al. for both PEI and PnPI. Lungwitz et al. used meth-ylation with methyl iodide to produce poly(N-methyl-ethylenimine) (PMEI) (variant on Scheme 2.13b). Freeh et and Lambermont-Thijs et al7 ... 

Synonyms Polyethylenimine 15 Definition Polymer of ethylenimine Formula (CH2CH2NH)n, avg. n = 15 Toxicology TSCA listed Uses Vise, control agent in cosmetics starch modification coatings inks adhesives petrol, industry metal treatment resins textiles in food-pkg. adhesives in resinous/polymeric food-contact coatings for polyolefin films in food-contact paper/paperboard in cellophane for food pkg. 

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