Polyaddition with condensation

A mechanism for self-promoted polyaddition with condensation can be formulated in the following general way, where M represents monomer and M an activated species capable of propagating or condensing. 

Figure 7. Variation of degree of polymerization (D.P.) with conversion for monomer-promoted polyaddition with condensation. The curves are calculated for kt = O.OOl, kp = 0.1, and for kc = 0.01 - 50, as indicated in the figure.

It is clear that Tgxp is a function of curing conversion or molecular weight (for linear polymers) at adiff. One can observe a noticeable difference between T xp and T for such processes of polymer synthesis as polyaddition or condensation polymerization reactions. It is especially important for polymers with high T . For many heat-resistant polymers, T is higher than the temperature limit of their chemical decomposition. We can never reach natural T for these polymers. For such polymers, one really measures only Tgxp, the value of which depends on the reaction conditions. For structure-glass transition temperature correlations of networks, T is the most important quantity. 

The third approaeh to synthetic polymers is of somewhat less commereial importance. There is in fact no universally accepted deseription for the route but the terms rearrangement polymerisation and polyaddition are commonly used. In many respects this process is intermediate between addition and condensation polymerisations. As with the former teehnique there is no moleeule split out but the kinetics are akin to the latter. A typical example is the preparation of polyurethanes by interaction of diols (di-alcohols, glycols) with di-isocyanates Figure 2.7). 

Polycondensation pol5mers, like polyesters or polyamides, are obtained by condensation reactions of monomers, which entail elimination of small molecules (e.g. water or a hydrogen halide), usually under acid/ base catalysis conditions. Polyolefins and polyacrylates are typical polyaddition products, which can be obtained by radical, ionic and transition metal catalyzed polymerization. The process usually requires an initiator (a radical precursor, a salt, electromagnetic radiation) or a catalyst (a transition metal). Cross-linked polyaddition pol5mers have been almost exclusively used so far as catalytic supports, in academic research, with few exceptions (for examples of metal catalysts on polyamides see Ref. [95-98]). 

The use of alkali-metal amides instead of the amine itself has the advantages of avoiding polyaddition reactions and the need of using an excess of amines (see above). This process has been applied to the synthesis of SMA. A chloromethylsilane was condensed with an amide preformed from an acidic amine function. In general, good yields were obtained.17 81 88 91... 

Ring-opening polymerization is different from the addition and condensation polymerizations described so far. It does not produce byproducts (e.g., water) as polycondensation does, and there is no unsaturated double bond in the monomers to lead to additional polymerization. However, some similarities do exist. Ringopening polymerization is initiated by the opening of a cyclic structure in the monomers and followed by polyaddition. As a result, a linear polymer with a chemical composition identical to that of the monomer is obtained. 

Barrere and Landfester [184] prepared a hybrid miniemulsion in which isophorone diisocyanate was condensation polymerized with dodecanediol to form polyurethane at the same time that the polystyrene or polyBA was free radical polymerized. Unlike previous work, the polyurethane was not prepared in organic solvent in advance. Therefore, in this one-pot synthesis, polyaddition and free radical polymerization both take place in the same particle. HD was used as the costabihzer. After miniemulsification, the polycondensation was allowed to take place, and then a free radical initiator was added to polymerize the styrenic or acrylic monomer. Molecular weight distributions were bimodal the PU had a substantially lower molecular weight than the polyacrylate. Neither intra- nor interparticle phase separation could be detected by TEM the particles appeared to be homogeneous. No measurements of grafting were made, but since there was no unsaturation in the PU, none was expected. 

Disulfide-bridged oligoferrocenes 3.18 (M <3500) were prepared in an attempt to copolymerize ferrocenedithiol with norbomadiene in the presence of AIBN in toluene [55, 56]. Rather than the expected radical-induced polyaddition [57] to give 3.17 (Eq. 3.8), condensation of the ferrocene monomer was observed with norbor-nene and nortricydane units as end-groups (Eq. 3.9). The isolated oligomers (3.18) were characterized by NMR spectroscopy and field-desorption mass spectrometry, and possessed a chain length of 2-12 repeat units as determined by GPC. 

Poly(amide-imides) may be prepared from polyaddition reactions of dialdoximes with bismaleimides, with an example of the structure shown from poly condensation of terephthaldoxime with N,N -[4,4 -... 

Recently, Neckers et. al. demonstrated that polyureas with back-bone azobenzene groups also showed photoviscosity effects under ultraviolet irradiation. Stille et. al. reported that the viscosity of polyquinoline (2) with backbone stilbene groups in di-m-cresyl phosphate /m-cresol decreased by as much as 24 % in the intrinsic viscosity value under the influence of ultraviolet light.The decrease is ascribed to the trans to cis isomerization of the stilbene groups. Because of the simplicity of the mechanism, the concept to introduce photoresponsiveness to polymers may be applied to other poly-condensation or polyaddition polymers. 

The chemistry of TPEs continuously changed with time and in this chapter the present-day situation is analyzed with emphasis on poly condensation, polyaddition, and chemical modification, which is often associated with the... 

We have demonstrated that the synthesis of ordered poly(acylhydrazide-amide-thioether) can be achieved by the combination of polyaddition and direct polycondensation from two nonsynunetric monomers, 4 (GCabX) and 5 (ZefZ) with a pair of synunetric monomers (YcdY), 6 (YccY) and 7 (YddY) using condensing agent 1. 

The following table contains the abbreviations and acronyms of names of polymeric materials whose base polymers were obtained by chain polymerization (addition polymerization), copolymerization, polycondensation (condensation polymerization), and polyaddition. Note that these abbreviations and acronyms do not apply in industry to polymers per se but to polymeric materials, i.e. polymers with or without additives, tillers, plasticizers, etc. 

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