Poly anionic preparation

Second, the conversion of one of the blocks into another type of structure by a suitable quantitative chemical reaction, allows a broad diversification of the properties of the available block copolymers. The best example of such an opportunity is probably the hydrogenation of poly(butadiene-b-styrene) copolymers, which yields a product close to a low density poly(ethylene-b-styrene) when starting from an anionically prepared diblock (including a certain amount, ca. 10 %, of 1.2 units), while a high density poly(ethy1ene-b-styrene)... 

The deliberate introduction of multifunctional branching into anionically prepared polydiene and poly (diene-co-styrene) polymers produces materials with unique morphological and viscoelastic properties (1-3). Work has included synthesis of symmetric star polymers produced by reaction of living polyanionic "arms" with multi-functional chlorosilane (4-9),... 

The MALDI-TOF spectrum of [G-3] poly(benzyl ether) dendrimer-po-ly(ethylene glycol) triblock copolymer shows a broad band of peaks between 4300 and 6100 D with resolution of the individual ethyleneoxide (44 D) units. The MALDI-TOF spectrum of a [G-3] dendrimer with two polystyrene blocks (molecular peak=8073 D) shows material with 6000-11,000 D and a broad band corresponding to material with 2 M+Ag+. SEC can be used to prove that the latter species is indeed an artifact of the mass spectroscopic method. The authors claim almost exact agreement between the polydispersities derived from MALDI-TOF and SEC [40]. This does, however, not leave any room for the unavoidable column spreading in the latter method. Furthermore, anionically prepared low MW polymers have a minimum polydispersity given by (1 + 1/DP) [41]. 

In the next section dealing with preparations we shall begin with mono-anions, and continue with gem and vicinal metal-centered di-anions, including the metalloles and polymetallated mono- and poly-anions. 

Poly(styrene-b-butadiene) was anionically prepared by the author [5] using n-butylithium and tetramethylethylenediamine. The product was used as a component in automotive tires. 

Sulfur-vulcanizable elastomers have been prepared that are designed to reduce hysteresis in tires by reducing the number of polymer free ends. The method for this preparation entails anionically preparing poly(styrene-co-butadiene) using a lithium thioacetal initiator followed by incorporation of a vulcanization agent into the elastomer terminus. 

Poly(l,3-cyclohexadiene-co-styrene) having a M of 63,603 daltons and containing up to 86% 1,3-cyclohexadiene has been anionically prepared using l,3-bis(l-lithio-l,3,3-trimethyl-butyl)benzene as catalyst. When hydrogenated, the material is converted into a high-performance resin. 

Intramolecular asymmetric induction has also been used in electrochemistry as in the reduction of optically active alcohol esters or amides of a-keto [469,470] and unsaturated [471] acids and oximes [472] and in the oxidation of olefins [473]. A maximum asymmetric yield of 81% was obtained in the reduction of (5 )-4-isopropyl-2-oxazolidinone phenyl-glyoxylate [470]. Nonaka and coworkers [474,475] found that amino acid A-carboxy anhydrides were polymerized with various electrogenerated bases as catalyst to give the poly(amino acids) with high chirality in high yields. Conductive chiral poly(thiophenes) prepared by electropolymerization can be used for chiral anion recognition [476]. 

The poly anions are built primarily of M06 octahedra, but they are prepared by starting with M042- ions. The polymolybdates are formed by the condensation of M0O42- unit and their composition depends upon the pH of the solution. 

Low molecular weight head-to-tail poly (y-crotonolactone), VIII, was prepared for comparison with the lactone polymers prepared in this study. The IR spectrum of the anionically prepared material (VIII), with strong absorptions in the region 1760 and... 

Poly(amino acids)2892 and polypeptides2893 can also be grafted onto starch. Starch was first alkylated in the presence of lithium naphthalene, and then the alkoxy derivatives were reacted with /V-carboxy anhydrides. Poly(amide amines) were produced by reacting amines with dioic acids on starch and then crosslinking with epichlorohydrin or 1,2-dichloroethane 2894 Grafting of starch with a synthetic polymer chain, for instance, polystyryl carboxylate anions prepared by an anionic polymerization, can be carried out on a blend of starch and cellulose functionalized by sulfonation, mesylation, or tosylation. In this manner, cellulose-starch graft copolymers were prepared.2895... 

The colloidal properties of anionically prepared poly(styrene-g-ethylene oxide) graft copolymers were studied by Candau et al. in different water/toluene/ alcohol mixtures by light and neutron scattering, NMR, and viscometry [307-309]. Aggregation numbers depend on mixture compositions with the highest values attained for water-rich systems. The micelles formed seem to have a core and shell conformation, with PS cores, in all cases studied. Dialysis experiments showed that the enhanced water-oil solubility was due to preferential solvation of the two segregated components of the copolymers by the solvent mixture and not to one specific solvent entrapment as is the case of classical microemulsions. 

Recently, Kambour et al. [6,7] reported on the miscibility of poly(styrene) and poly-p-bromostyrene) and its dependence on chain length and bromine content. The material studied, anionically prepared poly (styrene), was partially brominated so that the chain lengths of original sample and its substitution products could be assumed to be identical, but for a contribution of the bromine atoms. Kambour et al neglected the latter effect in their theoretical interpretation if the data. 

Sanji T, Isozaki S, Yoshida M, Sakamoto K, Sakurai H (2003) Functional transframation of poly (dialkylaminotrimethyldisilene) prepared by anionic polymerization of the masked disiienes. The preparation of a true polysilastyroie. J Organomet Chem 685(l-2) 65-69... 

Fluorinated poly(methacrylates) or poly(acrylates), rich in trifluoromethyl groups, exhibit superior performance of chemical inertness, excellent weatherability, low refractive index, lower dielectric constant, and special surface properties [14,61]. Poly(2,2,2-trifluoroethyl methacrylate), poly(MATRIF), is an important class of such materials. It has been extensively used in high performance coatings [17], photoelectric communications, and microelectronics [62]. Poly(MATRIF) is easily produced by free radical polymerization using bulk, solution, and emulsion polymerization methods [63]. Structural characterization of NMR of poly(MATRIF) prepared by radical and anionic polymerization has been studied. Syndiotactic structure was obtained by radical initiator in contrast to an isotactic structure achieved by anionic polymerization [64]. 

---