Polymerization and Polycondensation

Some industrially important polymeric materials can be prepared using the basic strategies discussed earlier. A representative example can be found in the synthesis of polyesters using the carbonylative polycondensation of aromatic dibromides and diols (Fig. 1-30) [237]. The underlying principle is no different from the fundamentals of carbonylative coupling presented earlier in Section 1.5.1.3. Replacement of the diols with hydrazides 86 similarly yields poly(acylhydrazide)s 87 [238]. The catalytic 

Synthesis of functional polymers from hydroboration of p-bromostyrene and coupling reaction catalyzed by PdCl2(dppf) (adapted from [241]). 

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Kinetic curves of phenylglycidyl ether consumption in the reaction with aniline in the presence of dimethylbenzylamine (DMBA) are presented in Fig. 15 a. As can be seen from this figure, addition of DMBA considerably increase the rate of monomer consumption in the initial and especially in the later stages of the reaction. The amount of the monomer consumed during polycondensation and polymerization can be readily determined by a parallel determination of the aniline consumption (Fig. 15 b). 

Thus, ESR data confirm (a) the lower-ring polycondensation and polymerization degree of HAs and FAs from organic amendments with respect to soil HAs and FAs and (b) the partial incorporation of the amendment on these structural properties into native soil HAs and FAs. 

Macromolecules are formed by polycondensation and polymerization. Both reactions have been and are precisely defined and differentiated. For formal reasons, the term polymerization is superior to polycondensation (both lead to the formation of polymers) and polycondensation is then designated by the compromise term condensation polymerization+. In my opinion, due to the differences in the mechanism and kinetics of polymerizations and polycondensations, a separate treatment of each of these polyreactions is justified. 

Liquid-phase processes oxidation, hydrogenation, sulfonation, nitration, halogenation, alkylation, sulfation, polycondensation, and polymerization (B5, B6, P14). 

There exist two main ways for the synthesis of polymers polycondensation and polymerization. A polycondensation is a series of chemical reactions between difunctional compounds thus the esterification of a diacid by a dialcohol produces a polyester. A polymerization is a chain reaction the polymers have at one extremity an active site, and they grow step by step by adjunction of monomers containing a double bond when a monomer clings to a chain, the double bond opens and the activity is transferred to the new extremity of the chain. Therefore, such a transformation requires an initiator able to create active sites. Industrially, the polymerization processes correspond to the largest tonnage and scientifically, for the preparation of good samples, they are also the most interesting. 

Poly(alkylene H-phosphonate)s can be synthesized by polycondensation and polymerization methods. 

Higher hydrocarbons may form stable coke at much higher S/C ratios than 1.4 as is known from many applications, because the polycondensed and polymeric clusters are not easily converted in the presence of steam. 

There are two very active special fields of phase-transfer appHcations that transcend classes (/) and 2) metal—organic reactions both with and without added bases, and polymer chemistry. Certain chemical modifications of side groups, polycondensations, and radical polymerizations can be influenced favorably by PTC. 

Block copolymers containing polysiloxane segments are of great interest as polymeric surfactants and elastomers. Polycondensation and polyaddition reactions of functionally ended prepolymers are usually employed to prepare well-defined block copolymers. The living polystyrene anion reacts with a,co-dichloropoly(dimethyl-siloxane) to form multiblock copolymers398. ... 

The DB obtainable in SCVP is DB=0.465 for r=kjk =l and reaches its maximum, DB=0.5, for r=2.6 [70,78]. This value is identical to that obtained in AB2 polycondensation when both B functions have the same reactivity [70,78]. Thus, hyperbranched polymers prepared by bulk polycondensation or polymerization contain at least 50% linear units, making this approach less efficient than the synthesis of dendrimers. 

Since sol-gel polycondensation and organic polymerization usually take place under different reaction conditions, the sequence of the reactions (organic polymerization prior to sol-gel condensation or vice versa) can be chosen by reaction conditions. 

In an attempt to avoid the polymerization/depolymerization equilibrium that occurs during melt polycondensation, Albertsson and Lundmark (1988) also studied the irreversible reaction of adipic anhydride with ketene. However, they reported very little difference in molecular weights when two ketene syntheses were compared to melt polycondensation and ringopening polymerization using a zinc catalyst (Albertsson and Lundmark, 1988). 

Polyanhydrides based on unsaturated and fatty acid-derived monomers are shown in Table III. Poly(fumaric acid) (PFA) was fist synthesized by Domb et al. (1991) by both melt polycondensation and solution polymerization. The copolymer of fumaric acid and sebacic acid (P(FA-SA)) has been synthesized and characterized (Domb et al., 1991 Mathiowitz et al., 1990b). The mucoadhesive properties of this polymer... 

Note 2 The earlier term polycondensation was synon5nnous with condensation polymerization. It should be noted that the current definitions of polycondensation and eondensative chain polymerization were both embraced by the earlier term polycondensation. 

Note 1 Reactive end-groups in telechelic polymers come from initiator or termination or chain transfer agents in chain polymerizations, but not from monomer(s) as in polycondensations and polyadditions. 

Several 0-protected aldonic acids and aldonolactones such as 16-21 have been used as monomers in polycondensation and ring opening polymerization reactions [32-34],... 

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