Alkyl-substituted styrene monomers

In the early composition of matter, process and product patents that IKC had filed, reference and claims to all types of substituted styrene homopolymers and copolymers in the syndiotactic configuration had been made. These became the practical basis for the development of film and fiber grade products with improved (in this case reduced) crystallization rates from the melt. The incorporation of small amounts of alkyl-substituted styrene monomers led to a new line of products for these markets and applications. The almost complete random copolymer of para-methyl styrene and styrene with these catalysts is the basis of this technology. Once it was discovered that this was effective, it was only a matter of optimizing the melt crystallization rate with... 

Thermoplastic resins produced from pure monomers such as styrene, alkyl-substituted styrenes, and isobutylene are produced commercially. An advantage of these resins is the fact that they are typically lighter in color than Gardner 1 (water-white) without being hydrogenated. Among the earliest resins in this category were those made from styrene and sold as Piccolastic. Styrene and alkyl-substituted styrenes such as a-methylstyrene are very reactive toward Friedel-Crafts polymerization catalysts. 

Heated, the compound (III) leads to the formation of a di-teri-butyl rutroxide radical (II) and an alkyl radical, CeHsC (H)CH3, that exhibits a chemical structure similar to that of the styryl radical. The choice of (III) as the capping agent comes from its absence of reactivity toward alkenes and from the low strength of the bond formed with the active site (Catala et al., 1995). It allows free radical polymerization of styrene and substituted styrene monomers at 90°C with complete control of the molecular weight and monomer consumption (Joussel et al., 1997). 

Monomer Reactivity Ratios for Alkyl-Substituted Styrenes (Vp) and -Chlorostyrene (V )... 

A drastic change of nitroxide stmcture was witnessed with the use of the commercially available DBNO (27). In particular, Moad and Rizzardo showed that the dissociation rate constant of a DBNO-based alkoxyamine was higher than any similar alkoxyamines based on cyclic nitroxides bearing tetra-methyl alkyl groups on the vicinity of the aminoxyl function. The first experimental studies were performed by the group of Catala where it was shown that the polymerization of styrene and substituted styrene monomers could be carried out at 90 ° C with all the criteria of control/livingness. However, the polymerization rate was independent of the alkoxyamine concentration and remained governed by the production of thermal radicals in the medium. The tert-butyl-tert-amyl nitroxide 28 was tested by Moad et to control the polymerization of MMA and appeared to be inefficient. 

Figure 15.3 illustrates that the free radical polymerization of PMI and styrene proceeds in an alternating manner [22,29,30]. Over a wide range of monomer ratio, the copolymerization (at low conversions) results in polymers with PMI content between 45 and 55 % and a Tg between 225 and 245 °C. The same type of alternation is observed in the copolymerization of styrene with maleic anhydride [31] and various A-alkyl-substituted maleimides [32-35]. It is... 

Most Grignard reagents are inert toward styrene (up to the temperature of spontaneous thermal polymerization). This is a significant difference from lithium alkyls, which are readily able to initiate styrenic monomers [123]. The only reported exception is p-vinylbenzyl magnesium chloride, which polymerized styrene in THF at O C, but not at — 78X [50,51]. Substitution at the puru-position of a phenyl ring may stabilize the benzyl anion, owing to the delocatlization of electrons, and favor ionic dissociation of... 

Peroxide-initiated, bulk copolymerization of MA with trifluoromethyl-, halo-trifluoromethyl-, halogen-, halo-alkyl-, etc., substituted styrene and a-methylstyrene monomers at 65-70°C, were studied briefly by Backman and... 

Included among the many types of vinyl monomers that have been subjected to photoinitiated cationic polymerization are styrene," substituted styrenes, a-methylstyrenes, N-vinylcarbazole, alkyl vinyl ethers, prop-l-en-l-yl ethers, ketene acetals, and alkoxyallenes. Most useful in the crosslinking photopolymerizations employed for UV curing applications are multifunctional vinyl ethers and multifunctional prop-l-en-l-yl ethers. A number of multifunctional vinyl ether monomers are available from commercial sources, while multifunctional prop-l-en-l-yl ethers can be readily prepared by catalytic isomerization from their corresponding allyl ether precursors. The photoinitiated cationic... 

In addition to providing fully alkyl/aryl-substituted polyphosphasenes, the versatility of the process in Figure 2 has allowed the preparation of various functionalized polymers and copolymers. Thus the monomer (10) can be derivatized via deprotonation—substitution, when a P-methyl (or P—CH2—) group is present, to provide new phosphoranimines some of which, in turn, serve as precursors to new polymers (64). In the same vein, polymers containing a P—CH group, for example, poly(methylphenylphosphazene), can also be derivatized by deprotonation—substitution reactions without chain scission. This has produced a number of functionalized polymers (64,71—73), including water-soluble carboxylate salts (11), as well as graft copolymers with styrene (74) and with dimethylsiloxane (12) (75). 

Figure 9-1 illustrates inductive influences in cationic polymerizations. The electron-releasing inductive influence of alkyl groups causes isobutene to polymerize very quickly at low temperatures where propylene reacts inefficiently and ethylene is practically inert. For similar reasons, a-methylstyrene (9-12) is more reactive than styrene, and substitution of an electron-withdrawing halogen for an ortho- or/ ara-hydrogen, decreases the monomer reactivity still further. As a corollary, ortho- and para-electron-releasing substituents (RO—, RS—, aryl) increase cation stability and monomer reactivity. 

Diphenylmethyl Carbanions The carbanions based on diphenylmethane (p/fj, = 32) [2] are useful initiators for vinyl and heterocyclic monomers, especially alkyl methacrylates at low temperatures [78]. 1,1-Diphenylalkyllithiums can also efficiently initiate the polymerization of styrene and diene monomers that form less stable carbanions. Diphenylmethyllithium can be prepared by the metallation reaction of diphenylmethane with butyllithium or by the addition of butyllithium to DPE as shown in Equation 7.13. This reaction can also be utilized to prepare functionalized initiators by reacting butyllithium with a substituted DPE derivative [78]. Addition of lithium salts such as lithium chloride, lithium tert-butoxide, or lithium 2-(2-methoxyethoxy)ethoxide with... 

A patent was issued to Wertmer and coworkers [271] for controlled radical (co)polymerization of vinyl monomers mediated by nitrones substituted by longer alkyl groups that contained as much as 18 carbon atoms. The nitrone was simply heated in the presence of peroxide and a monomer, such as styrene at 130°C for 24 h. High-molecular-weight polystyrene, = 98,000-146,000 was formed. The ratio of however, was not disclosed... 

A parallel development was initiated by the first publications from Sawamoto and Matyjaszweski. They reported independently on the transition-metal-catalyzed polymerization of various vinyl monomers (14,15). The technique, which was termed atom transfer radical polymerization (ATRP), uses an activated alkyl halide as initiator, and a transition-metal complex in its lower oxidation state as the catalyst. Similar to the nitroxide-mediated polymerization, ATRP is based on the reversible termination of growing radicals. ATRP was developed as an extension of atom transfer radical addition (ATRA), the so-called Kharasch reaction (16). ATRP turned out to be a versatile technique for the controlled polymerization of styrene derivatives, acrylates, methacrylates, etc. Because of the use of activated alkyl halides as initiators, the introduction of functional endgroups in the polymer chain turned out to be easy (17-22). Although many different transition metals have been used in ATRP, by far the most frequently used metal is copper. Nitrogen-based ligands, eg substituted bipyridines (14), alkyl pyridinimine (Schiff s base) (23), and multidentate tertiary alkyl amines (24), are used to solubilize the metal salt and to adjust its redox potential in order to match the requirements for an ATRP catalyst. In conjunction with copper, the most powerful ligand at present is probably tris[2-(dimethylamino)ethyl)]amine (Mee-TREN) (25). 

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