Poly diol formation

Figure 3. First-order rate plots for poly(propylene ether) diol formation at 50°C...

Water-borne polyurethane coatings are formulated by incorporating ionic groups into the polymer backbone. These ionomers are dispersed in water through neutrali2ation. The experimental 1,12-dodecane diisocyanate (C12DI Du Pont) is especially well suited for the formation of water-borne polyurethanes because of its hydrophobicity (39). Cationomers are formed from IPDI, /V-methyIdiethan olamine, and poly(tetramethylene adipate diol)... 

Several different analytical and ultra-micropreparative CEC approaches have been described for such peptide separations. For example, open tubular (OT-CEC) methods have been used 290-294 with etched fused silicas to increase the surface area with diols or octadecyl chains then bonded to the surface.1 With such OT-CEC systems, the peptide-ligand interactions of, for example, angiotensin I-III increased with increasing hydrophobicity of the bonded phase on the capillary wall. Porous layer open tubular (PLOT) capillaries coated with anionic polymers 295 or poly(aspartic acid) 296 have also been employed 297 to separate basic peptides on the inner wall of fused silica capillaries of 20 pm i.d. When the same eluent conditions were employed, superior performance was observed for these PLOT capillaries compared to the corresponding capillary zone electrophoresis (HP-CZE) separation. Peptide mixtures can be analyzed 298-300 with OT-CEC systems based on octyl-bonded fused silica capillaries that have been coated with (3-aminopropyl)trimethoxysilane (APS), as well as with pressurized CEC (pCEC) packed with particles of similar surface chemistry, to decrease the electrostatic interactions between the solute and the surface, coupled to a mass spectrometer (MS). In the pressurized flow version of electrochromatography, a pLC pump is also employed (Figure 26) to facilitate liquid flow, reduce bubble formation, and to fine-tune the selectivity of the separation of the peptide mixture. 

The ease of formation of alcoholates and adducts can be related to both the acidity and the geometry of the poly hydroxy compound. The geometry is important, in that the chelate ring must possess a minimum of strain in order to allow the complex to possess the maximum stability. Reaction of a cyclic 1,2-diol with a metal hydroxide is physically impossible if the hydroxyl groups are oriented in directions that are exactly opposite (180°) to each other. Cyclic 1,3-diols can form chelates if both of the hydroxyl groups are cis and axial. An example of this is the reaction of 1,6-anhydro-... 

There is a very wide variety of condensation reactions that, in principle, can be used to form high polymers. However, as explained above, high polymers can be obtained only in high-yield reactions, and this limitation severely restricts the number of condensation reactions having any practical importance. A specific example of an impractical reaction is the formation of poly-1,4-butanediol by reaction of 1,4-dibromobutane with the disodium salt of the diol ... 

Diols are predominantly used for chain extensions to give a product with only urea bonds. The progress is similar to the formation of the poly(urea-urethane), but with only urethane bonds. See Figure 2.32. 

Polyesterification. High molecular weight linear polyester resins, such as poly(ethylene terephthalate) (PET), poly(propylene terephthalate) (PPT), and poly(butylene terephthalate) (PBT), can be produced by either transesterification of dimethyl terephthalate (DMT) with an excess of the corresponding diol or by direct esterification of terephthalic acid (TPA). Tetraalkyl titanates, such as TYZOR TPT or —TYZOR TBT, have been found to be excellent catalysts for either of these reactions. However, in the case of PET, the residual titanate catalyst reacts with trace quantities of aldehydic impurities produced in the polymerization process to generate a yellow discoloration of the polymer (468,469). In the case of PPT and PBT, where the color of polymer is not as critical, organic titanates are the catalyst of choice because of their greater reactivity than antimony or tin (470). Numerous processing variations have been described in the literature to minimize formation of tetrahydrofuran in the PBT process (471—472). 

Formation of Di- or Poly-O-substituted Derivatives from fraru-Diols... 

Porous affinity membranes based on hydrolyzed poly(GMA-co-EDMA) grafted with glicidyl methacrylates oligomers were also reported [2,60]. Tennikova et al. [2] prepared functionalized macroporous poly(GMA-co-EDMA) membranes by reaction with propane sulfone, diethylamine, or water, leading to the formation of corresponding sulfonic acid, diethylamino or diol-derivatized stationary chromatographic phases. Unfortunately, the poly(GMA-co-EDMA) membranes are mechanically weak and due to their hydrophobic character may cause nonspecific adsorption of proteins. 

Pyrolysis process for poly(2-hydroxyethyl methacrylate) occurs similarly to that for other methacrylic acid esters. The formation of 2-methyl-2-propenoic acid 2-hydroxyethyl ester, the monomer, shows that unzipping is a significant part of the process. Some other compounds in the pyrolysate also are generated from the polymer cleavage, such compounds including 2-methyl-2-propenoic acid ethenyl ester, propanoic acid, 2-methyl-2-propenoic acid, ethanol, etc. On the other hand, some compounds are not expected in the pyrolysate and they can be impurities or additives. Examples of such compounds are the hydrocarbons (undecene, dodecane, 1-dodecene, etc.), the esters of ethylene diol and the free 1,2-ethandiol, etc. The initiator AIBN and its decomposition products 2-methyl-2-propenenitrile and 2-methylpropanenitrile identified in the pyrolysate show that the polymer was obtained using AIBN as initiator. 

The results of pyrolysis for poly[(1,6-hexyl-1,2-ethyl carbonate)diol 4,4 -methylene-bis(phenyl isocyanate)]-co-[1,4-butandiol 4,4 -methylenebis(phenyl isocyanate)] show that the pyrolysis process for this copolymer is in many respects similar to that of other polycarbonates. The possible formation of 4,4 -methylenebisbenzeneamine, which has the base peak at 198 a.u. corresponding to the molecular ion, and which is likely to be formed in the pyrolysate, is not detected in the pyrogram. This compound does not elute in the experimental conditions used for the pyrolysate separation, and its formation cannot be verified. 

Reaction with difunctional amines (see the next paragraph) allows the formation of poly (urethane-co-urea) and further extends the versatility of the segment architecture. For further control of the structure, a prepolymer is formed. The reaction, such as the polyurethane reaction shown above, is carried out with excess di-isocyanate so that an isocyanate-terminated prepolymer is obtained. The isocyanates used are typically aromatic, such as toluene di-isocyanate. This prepolymer is then reacted with a short-chain diol or diamine (for a polyurea) to form the final polymer. 

The earlier example of the formation of a poly(urethane-co-urea) showed the change in properties made possible by including a comonomer (in that case a difunctional amine) together with the usual diol for reaction with a di-isocyanate. This can be extended to a wide range of step polymerizations where an additional reactant is added. Examples could be the use of two AB-type monomers (e.g. amino acids) or two AA (e.g. diacids) to react with one BB (a diamine) to form co-polyamides. Seveml features of step polymerization help in understanding the resultant copolymer. For example, since high-molar-mass polymer is formed only late in the reaction, the composition of the copolymer will be that of the feed ratio of the monomers. 

You ve got a big day planned in the city an afternoon at the ballpark watching your favorite player belt home runs, followed by dinner and disco dancing at a retro club called Saturday Night Fever. The player s uniform and your own disco outfit are almost certainly made from polyester, which is a condensation polymer similar to nylon. Polyesters are made from the reaction of a diol (a compound with two alcohol functional groups) with a di-carboxylic acid. Figure 17.34 shows tbe steps for the formation of poly(ethylene terephthalate) from ethylene glycol and terephthalic acid. 

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