Condensation monomers

In estimating the enthalpy of polymerization, the physical state of both starting monomer and polymer must be specified. Changes in state are accompanied by ethalpy changes. Therefore, they also affect the level of the polymerization enthalpy. The AfT forN ylylene previously mentioned is apphcable to the monomer as an ideal gas. To make comparisons with other polymerization processes, most of which start with condensed monomer, a heat of vaporization for N ylylene is needed. It is assumed herein that it is the same as that for N ylene, 42.4 kJ /mol (10.1 kcal/mol). Thus the AfT of the hquid monomer -xylylene is 192.3 kJ/mol (46.0 kcal /mol). 

TNT-based condensation monomers. The synthesis of these materials is presented humorously by Russian authors a as consequence of the end of the Cold War. The synthesis, based on a very easy nucleophilic displacement of an activated nitro group, offers many possibilities for the synthesis of diamines bearing a functional group.117... 

Tris(hydroxymethyl)propane (TMP) TNT-based condensation monomers, 297 Toluene diamine (TDA), 222 Toluene diisocyanate (TDI), 200, 219 dimer of, 240... 

Self-condensing monomers of the form AMB avoid a stoichiometry restriction. The idea is to synthesize the monomer using conditions where the A and B endgroups are not reactive but to polymerize the monomer under conditions where the endgroups do react. An important example is the polymerization of PET. A large excess of ethylene glycol is reacted with terephthalic acid to form a nominal trimer, diglycol terephthalate ... 

The polydispersity is 2 for perfect stoichiometry or self-condensing monomers, but Equation (13.4) shows that oo for this case. PD = 2 is an asymptotic value that applies exactly only in the limit of high molecular weight. However, PD closely approaches 2 at quite low chain lengths. 

Research on fluorine-containing condensation polymers is rather limited compared to that on fluorine-containing addition polymers. This fact is attributed to the difficulty in synthesis and the high cost of fluorine-containing condensation monomers. Recently, 2,2-bis(4-hydroxyhpenyl)-1,1,1,3,3,3-hexafluoropropane (Bisphenol AF) with a hexafluoroisopropylidene unit, HOC6H4C(CF3)2-C6H4OH, was produced commercially from hexafluoroacetone and phenol, and now Bisphenol AF and its derivatives are available as condensation monomers. 

Another raw material potentially useful for the synthesis of condensation monomers is 2,4,6-trinitrotoluene (TNT) a well-known military explosive [20, 21]. Presently in a number of countries a large amount of ammunition liable to liquidation has been accumulated. Its major explosive component is TNT, and thus its utilisation has become a basic challenge [20, 21]. 

Most of the syntheses for condensation monomers using chloral employ well-known reactions... 

Of numerous chloral condensations with aromatic hydrocarbons the most interesting for the synthesis of condensation monomers are the reactions with benzene [3], toluene [4], acenaphthene [5], phenol [6], anisol [7], acetanilide [8] and halobenzenes like chlorobenzene [9] and fluorobenzene [10]. In general terms, these reactions proceed according to Scheme 2.2 and give the desired 1,1,1-trichloro-... 

The preparation of polymers from heterocyclic monomers that contain polymerizable functional groups undoubtedly constitutes the most common method of incorporating heterocycles into polymeric materials. Polymer-forming reactions are of two possible types addition reactions and condensation reactions. Addition monomers in general contain a site of unsaturation, i.e. a double or triple bond, through which polymerization occurs by successive single bond formation from one monomer to the next. With condensation monomers a bond is formed between two monomers with concomitant elimination of a... 

Condensation monomers having the benzimidazolin-2-one ring system have found utility as modifiers in polyester synthesis. In particular, halogenated diols (73) and dicarboxylic acids (74) may be incorporated (78MI11100) into polyethylene terephthalate) or poly(butyl-ene terephthalate) at fairly low levels to impart flame retardancy. This can be accomplished without adverse effects upon other polymer properties. 

The Michael addition of nucleic acid bases to dimethyl itaconate (137) has been utilized to prepare a number of condensation monomers (Scheme 39) (80MI11110). Reaction of active esters (138) with various diamines produces polyamides having the bases as pendant groups. 

The propellants derived from nitrate ester-based binders possessed the undesirable characteristics associated with nitrate ester groups such as thermal instability, hydrolytic instability, and impact instability (especially for highly nitrated compositions). For this reason a study was undertaken to prepare polymeric binders in which oxygen is carried in the form of the more thermally and hydrolytically stable nitro group. Aerojet General Corp., working with both the Purdue and the Ohio Research Foundations, carried out the bulk of these studies. The following are typical of the condensation monomers synthesized by Aerojet ... 

A polyurethane derived from one combination of these condensation monomers is ... 

A wide range of monomers, such as the condensation monomers shown here, were synthesized by Thiokol, Olin-Mathieson, and Rohm and Haas (10,11). 

A perfluoroacrylate monomer was flash evaporated at 100 millitorr and exposed to polypropylene fibers pretreated in a plasma field within one second while the fabric was traveling at 50 m/min. The condensed monomer layer was then cured in-line by electron beam radiation within 100 milliseconds resulting in a 0.1 pm perfluoroacrylate coating on the material surface. The product had an adequate repellency for both water and oil and a surface energy of 27 dyne/cm. 

Unlike the CNT for homogeneous nucleation, whose theoretical foundation has not been advanced since late 30s, the theoretical formalism of the ion-induced nucleation theory has been recently improved and extended. The critical importance of the dipole moment of condensing monomers and pre-nucleation clusters have been pointed out in the series of recent publications of Nadykto with coauthors [34-39] and, more recently, Leopold with co-authors [69]. The classical ion-induced nucleation theory has been advanced through the incorporation of the effect of the polar host vapour molecule-charged cluster interactions and some of the serious shortcomings of the original model have been successfully corrected [36]. 

---