Polymerization, reactivity

Here the radical 1 acts as a strong terminator to prevent the formation of oligomers and polymers. On the other hand, it is expected that the substituted diphenylmethyl radicals which are less stable than 1 serve as both initiators and primary radical terminators. In fact, it was reported [84] that the apparent polymerization reactivities decreased in the following order diphenylmethyl, phenylmethyl, and triphenylmethyl radicals, which were derived from the initiator systems consisting of arylmethyl halides and silver. 

Fig. 15 Viscosity dependence of the polymerization reactivity of a UV-curable phenoxy-divinyl-ether (Iq =17 mW cm-2).

Fig. 6 Stacking model for the muconate derivatives in the crystalline state and the definition of stacking parameters used for the prediction of the topochemical polymerization reactivity, d c the intermolecular distance between the 2 and 5 carbons, is the stacking distance between the adjacent monomers in a column. 6 and 02 are the angles between the stacking direction and the molecular plane in orthogonally different directions [59]...

TFDB strongly affects the reduction of amino group reactivity by introducing. -CF3 in the meta (m-) position. The polymerization reactivity of diamines and... 

A clear consensus47 156>166) has emerged which indicates that various extents of ether complexation with active centers can reduce their reactivity in the chain propagation event. If cation-monomer coordination is important, the presence of ether in the coordination sphere might be expected to lead to less monomer interaction with a subsequent reduction in polymerization reactivity. Clearly, there is a need for further work, experimental and theoretical, on this topic. 

Tsukahara Y (1994) In Macromolecular design concept and practice, macromonomers, chap 5 Characterization, polymerization reactivity and application. Polymers Frontiers International... 

Seko, N., Basuki, F Tamada, M. and Yoshii, F. (2004) Rapid removal of arsenic(V) by zirconium(IV) loaded phosphoric chelate adsorbent synthesized by radiation induced graft polymerization. Reactive and Functional Polymers, 59(3), 235-41. 

Compared with 49, 2,5-dioxabicyclo[2.2.2]octan-3-one (54) prepared from sodium 3,4-dihydro-2//-pyran-2-carboxylate has a much low polymerization reactivity [54] Lewis acids such as antimony pentachloride, phosphorus pentafluoride, and boron trifluoride etherate were not effective at all to initiate the polymerization of 54. Trifluoromethanesulfonic acid induced the polymerization of 54, but the yield and molecular weight of the polymer were low. Bicyclic lactone 54 was allowed to polymerize with anionic and coordination initiators such as butyl-lithium, lithiumbenzophenone ketyl, and tetraisopropyl titanate. However, the... 

Touring the past five years we have shown that many stable organic cations are useful initiators for polymerizing reactive olefins and cyclic ethers (I, 2, 3, 4, 5, 27). Compared with more common initiators for cationic polymerization (31), the stable salts allow for complete characterization of the catalyst system and give rapid, highly reproducible polymerizations. In addition many of the salts used are stable indefinitely in the crystalline state, which makes the experimental techniques easy and convenient. 

By using this method, they determined the rate constant of the propagation of endo-and exo-2-methyl-7-oxabicydo[2.2.1]heptaneZ1,22 and endo- and exo-2-tert-butyl-7-oxa-bicyclo[2.2.1]heptaneZ5. In these systems the polymerization proceeds via SN2 reaction between monomer and the propagating oxonium ion as was the case for the monocyclic ethers. They achieved the first case of a quantitative comparison of the polymerization reactivity between monocyclic and bicyclic ethers in the polymerization of exo-2-methyl-... 

A limited kinetic investigation has been carried out on promotors for vanadium catalysts (VO(Ot-Bu)3/Al2Et3Cl3) in ethylene polymerization [234]. It was shown that esters of trichloroacetic acid, added continuously during the polymerization, reactivated the catalyst and permitted polymerization to be carried out at 120°C. Under these circumstances over 250 polymer chains were produced per vanadium atom and the polymers had /Mn ratios close to 2.0, which would be anticipated for a single catalytic entity. 

Thirty years later, we discovered the topochemical polymerization of various 1,3-diene monomers giving a highly stereoregular polymer in the form of polymer crystals. When ethyl (Z,Z)-muconatc was photoirradiated in the crystalline state, a tritactic polymer was produced [18, 19], in contrast to the formation of an atactic polymer by conventional radical polymerization in an isotropic state. Thereafter, comprehensive investigation was carried out, for example, the design of monomers, the crystal structure analysis of monomers and polymers, and polymerization reactivity control, in order to reveal the features of the polymerization of 1,3-diene monomers [20-23], Eventually, it was revealed that the solid-state photoreaction... 

Matsumoto, A., Furukawa, D., Mori, Y., Tanaka, T. and Oka, K. (2007) Change in crystal structure and polymerization reactivity for the solid-state polymerization of muconate esters. Cryst. Growth Des., 7, 1078-1085. 

Bijsterbosch, H.D. Stuart, M.A.C. Fleer, G.J. Adsorption kinetics of diblock copolymers from a micellar solution on silica and titania. Macromolecules 1998, 31, 9281-9294. lijima, M. Nagasaki, Y. Okada, T. Kato, M. Kataoka, K. Core-polymerized reactive micellesm from heterotelechelic amphiphilic block copolymers. Macromolecules 1999, 32, 1140-1146. 

PHOTOINITIATED CATIONIC POLYMERIZATION REACTIVITY AND MECHANISTIC ASPECTS... 

In another work, improvement of polymerization reactivity of epoxides was attempted [148]. Styrene monomers were modified with epoxide functions that are inert toward radicallic species, and then polymerized in the presence of azobisiso-butyronitrile (AIBN). The polymers, ultimately, were cross-linked by sulfonium salt induced photopolymerization of the epoxide groups (Scheme 11.45) [148]. Kinetic results indicate that polymers containing silicon in their pendant group has the highest cross-linking reactivity. 

In addition to electrochemical polymerization, reactive monomers can be polymerized onto surfaces by using radio frequency (rf) plasma polymerization [194-197]. In this technique an electric discharge through the vapor forms a reactive plasma that chemically modifies the surface. Examples of applications of rf plasma-polymerized surfaces include the formation of (C2F4) films on fiber optic sensors for detection of volatile organics [198] and the formation of alkylamine surfaces on glass fibers by plasma treatment for subsequent chemical modification [199]. 

S. Sugiyama, S. Tsuneda, K. Saito, S. Furusaki, T. Sugo and K. Makuuchi, Attachment of Sulfonic Acid Groups to Various Shapes of PE, PP and FIFE by Radiation-Induced Graft Polymerization, Reactive Polym., 21 (1993) 187. M. 

---