Phthalic anhydride copolymerization

Phthalic anhydride, a polyol, and an unsaturated fatty acid are usually copolymerized to unsaturated polyesters for coating purposes. Many other combinations in variable ratios are possible for preparing these resins. The 1998 U.S. production of polyesters was approximately 1.7 billion pounds. 

Fig. 1. Effect of hexadecyltrimethylammonium bromide (CAB) on the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone (0.5 mol/1) with phthalic anhydride (0.5 mol/1) in nitrobenzene at 120 °C56)...

Fig. 3. Conductivity curves of the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone (0.5 mol/1) with phthalic anhydride (0.5 mol/1) in o-xylene at 120 °C initiated by various initiators.57) 1 — tri-n-hexylamine (0.025 mol/1) 2 - tri-n-hexylamine (0.025 mol/1) and cyclohexanol (0.025 mol je 1) 3 — tri-n-hexylamine (0.025 mol/1) and benzoic acid (0.025 mol/1) 4 — hexadecyltrimethyl-ammonium bromide (0.005 mol/1)...

The effect of the anion on the copolymerization rate is controversial. Hilt et al.41 established for different sodium halides the following order of efficiency F < Cl < Br < J . This order was interpreted on the basis of the increase in nucleophilicity or polarizability of the anions. Sfluparek and Mleziva 43) observed that the reaction rate of the benzoate anion was about twice as high as that of the bromide anion in the copolymerization of epichlorohydrine with phthalic anhydride. On the other hand, Luston and Manasek56) did not detect any effect of the anion size on the copolymerization rate initiated by tetramethylammonium and tetrabutylammonium halides. 

Solvent polarity influences the rate of copolymerization. Thus with increasing dielectric constant of the solvent, the copolymerization rate rises as a result of the increase in the dissociation constants of the active species. The apparent rate constant for the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride, initiated by hexadecyltrimethylammonium bromide56), increases from 4.65 x 10 4 s 1 in o-xylene to 6.84x 10 4 s-1 in nitrobenzene. Hilt et al.S4) proposed a suitable model illustrating the effect of solvent polarity in the copolymerization of phthalic anhydride with ethylene glycol carbonate in a mixture of nitrobenzene and trichlorobenzene (Table 4). With increasing fraction of the more polar nitrobenzene, the rate of copolymerization increases. 

Table 4. Reaction rates and dielectric constants of solvents and reaction mixtures for the copolymerization of ethylene glycol carbonate (0.1 mol) with phthalic anhydride (0.1 mol) in, 100 ml of solvent initiated with KC1 (0.001 mol-%) at 200 °C. 541 (Reproduced by courtesy of Hiithig and...

Equation (31) allows the determination of the ratio of propagation rate constants k3/k2 by correlation of the experimental results obtained in copolymerization using equimolar ratios of monomers with the results obtained at non-equimolar monomer ratio and excess of anhydride (an excess of epoxide should not be used because of homopolymerization of the monomers at high degree of conversion). A value of k3,/k2 equal to 0.2 0.1 was found for the system 2-hydroxy-4-(2,3-epoxypropoxy) benzophenone-phthalic anhydride in nitrobenzene initiated by hexadecyltrimethyl-ammonium bromide 56). 

Experimental results on the copolymerization of phthalic anhydride with ethylene glycol carbonate initiated by UC-labelled sodium benzoate (Table 5) or potassium benzoate show 4l,42,54) that the molecular weights of the copolymers formed decrease with increasing initiator concentration. 

Fischer 39 40> did not observe any effect of allyl alcohol on the copolymerization of allyl glycidyl ether with phthalic anhydride. Reaction rates were identical and indpendent of proton donor concentration. This finding indicates that the presence of... 

Second-order kinetics with respect to the amine and epoxide was also found by Antipova et al. 65) for the curing of epoxy resins with hexahydrophthalic anhydride, by Sorokin et al.321 for the reaction of phenylglycidyl ether with phthalic anhydride in the presence of butanol, Luston and Manasek 45 74) for the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride in the absence or in the presence of proton donors, and Kudyakov et al. 98) for the curing of epoxy resins with maleic anhydride. 

Diazocinyl-substituted phthalic anhydride 159 (R is inert, m = 0-3), prepared from 104 and the appropriately substituted acid chloride, underwent self or copolymerization to give polyamide-polyimides (83USP4391751). 

Figure 5.3 Reaction mechanism of the strictly alternating copolymerization of phenyl glycidyl ether (PGE, 2) and phthalic anhydride (PA, 3) initiated by imidazoles (la-c). (Leukel et al., 1996. Copyright 2001. Reprinted by permission ofWiley-VCH)...

Similar to the above discussed processes, the photoinitiation of the copolymerization between cyclohexene and AN in the presence of pyromellitic dianhydride or phthalic anhydride is based on the sequence of PET and proton transfer [30]. Consequently, the copolymerization rate with the former acceptor (Rp = 1.6x 10-4moll-1 s-1) is higher than this of the latter (Rp = 1.4x 10-4moll-1 s-1 [AN] = 4.5 mol l-1, 30°C). Interestingly, the average-molar weights of the alternating copolymers lie between 1000-2000 g mol- The reason for this very small value is possibly an efficient primary radical termination due to the formation of the two radicals IV and V see Eq. (4). Exact polymer characterization data are not available, so far. 

Solution As we shall see in Chapter 8, the copolymerization of maleic anhydride and styrene shows a strong tendency toward alternation (ri rj = 0.06). Consequently, a maleic anhydride-based unsaturated polyester cross-hnked with styrene forms a large number of short cross-links, resulting in a rigid polymer. With the addition of phthalic anhydride, the tendency toward alternation is reduced due to the occasional intervention of phthahc anhydride. The reduction of cross-link density results in a less rigid polymer. 

MALDI-TOF analysis showed that imidazoles used as initiators in the strictly alternating copolymerization of phenylglycidyl ether (PGE) and phthalic anhydride (PA) remain chemically bound to the polyester chains during the whole reaction. °... 

Sulfonated polyimides (sPI) are another type of ionomers that have been prepared [5] by copolymerization of 4,4 -diamino-biphenyl 2,2 -disulphonic acid (BDSA), 4,4 -oxydianiline (ODA), and naphtalenic or phthalic anhydrides. Polyimide structures based on six-membered rings derived from naphtalenics anhydrides, such as 1,4,5,8-naphtalene tetracarboxylic dianhydride (NTDA), shown in Fig. 6.8, are more hydrolitically stable than the five-membered rings basedoxy-diphthalic anhydrides (ODPA). 

Unsaturated polyesters with molecular weights of several thousand are made commercially by condensing maleic anhydride or phthalic anhydride with ethylene glycol or propylene glycol. The subsequent free radical copolymerization with 30-35% by wt styrene leads to a cross-linked product which possesses exceptionally good mechanical properties, particularly when reinforced with glass fiber. The thermosetting properties... 

Many polyester acrylates are well known as prepolymers. A copolymerized ester of an open ring reacted on epoxypropylacrylate with phthalic anhydride ... 

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