Chain effects, ethylene glycol

When MDI was used in the polymer synthesis, irrespective of the synthesis route it obtained homogeneous soluble polymers inseparable in fractions, by selective dissolution in DMF. Certainly, the sequence of ordering on the macromolecular chain differs from a PU synthesis route to another. As mentioned, the reaction rate between phenyl isocyanate (FI) and chain extender, ethylene glycol (EG) was found by us to be 4 times higher than the reaction between FI and PEA when measured separately, and 11.6 higher respectively if they are in a mixture (EG + PEA) (synergetic effect) [45,89]. 

When PET is extracted with water no detectable quantities of ethylene glycol or terephthaUc acid can be found, even at elevated extraction temperatures (110). Extractable materials are generally short-chained polyesters and aldehydes (110). Aldehydes occur naturally iu foods such as fmits and are produced metabohcaHy iu the body. Animal feeding studies with extractable materials show no adverse health effects. 

Benzonatate [104-31 ] (46) is a unique compound which appears to have both central and peripheral antitussive effects. Stmcturally it is a derivative of ji)-aminoben2oic acid and contains a long poly(ethylene glycol) side chain. The peripheral effects ate the result of local anesthetic action on the pulmonary stretch receptors. Clinical activity was first reported in 1955 (65). 

Polyethylene glycol (PEG) consists of repeating units of ethylene glycol forming linear or branched polymers with different molecular masses. Pegylation is the process by which PEG chains are covalently attached to lEN molecules. Pegylation confers a number of properties on lEN-a molecules, such as sustained blood levels that enhance antiviral effectiveness and reduce adverse reactions, as well as a longer half-life and improved patient compliance (Kozlowski et al. 2001). 

Li WL, et al. Low-pH-sensitive poly(ethylene glycol) (PEG)-stabilized plasmid nanolipoparticles effects of PEG chain length, lipid composition and assembly conditions on gene delivery. J Gene Med 2005 7 67. 

As discussed for biphenol-based phosphites, phosphites derived from ClMeO-biphenol should also be sterically more demanding and have an increased ring size as compared to catechol-based phosphites. Moreover, by comparing the catalytic results of biphenol- and ClMeO-biphenol-based ligands, conclusions on the influence of the substitution pattern and resulting electronic effects on the activity and selectivity in the hydroformylation can be drawn. Therefore, ClMeO-biphenol-based phosphites with PEG side chains consisting of one to three ethylene glycol units were included in the present study. 

The first step involves preparation of a bifunctional "living" precursor, of known molecular weight and low polydispersity. Crosslinking can be achieved either by the addition of stoichiometric amounts of a multifunctional electrophilic deactivator, or by adding small a small amount of a bifunctional monomer (such as DVB or ethylene glycol dimethacrylate), the polymerization of which will be initiated by the carbanionic sites of the precursor. In either case, the precursor chains become the elastically effective chains of the networks. The experimental conditions... 

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