Reactions with Vinyl Polymers

Department of Materials Science and Engineering, The Pennsylvania State University University Park, PA 16802 

Equation 1 illustrates a synthetic scheme which we have used in the preparation of polyolefin graft copolymers. Borane group containing polyolefin copolymers (I) were obtained by direct copolymerization [9,10] of a-olefin/borane containing a-olefin and a 

The free radical polymerized functional polymers with controllable molecular weight are therefore chemically bonded to the side chains of polyolefin (II). One example of PP-g-PMMA [12,13] is shown in Table 1. 

Run Mole % Borane 02 in PP (ml/hr.) Monomer/ Solvent Reaction Time (hrs.) Mole % MMA in Polymer 

Equation 2 illustrates another route to prepare graft copolymers, involving the preparation of polyolefin containing para-methylstyrene groups (I1). 

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The first type of addition (I) is known as head-to-tail addition and the second kind is called head-to-head . For mainly steric reasons the addition reactions with vinyl polymers are predominantly the head-to-tail variety giving a polymer which has alternating —CH2— and —CHX— units as shown below. 

Some degradation reactions occur without an increase in cross-linking or a lessening in chain length. Thus, with minute amounts of HCl, water, ester, etc. elimination can occur with vinyl polymers giving localized sites of double bond formation. Because such sites are less flexible and more susceptible to further degradation, these reactions are generally considered as unwanted. 

The modification of the properties of fibrous cotton cellulose through free-radical initiated copolymerization reactions with vinyl monomers has been investigated at the Southern Laboratory for a number of years. Both graft and block copolymers are formed. Under some experimental conditions the molecular weight of the polyvinyl polymer, covalently... 

Starch thiols can have the SH group directly on the pyranose ring or in a side chain. There are several methods of synthesizing starch thiols of the first type. One of them is based on the pyrolysis of starch xanthates (32), but the reaction proceeds in two parallel routes one producing thionates (35) and the other producing thiols (37).2675,2677 Reduction of starch xanthates with NaBPU in alkali is another approach to thiols. Thiols prepared in this manner were subjected to graft polymerization with vinyl polymers. Nucleophilic substitution of the chlorine... 

There are basically three types of thermal degradation reactions for vinyl polymers [36,37] (1) nonchain scission (2) random chain scission and (2) depropagation. In practice, mechanisms 2 and 3 blend into one another, with many polymers showing evidence of both processes. 

Interactions of ions and ion pairs with vinyl polymers of crown ethers were shown to be considerably more efficient than such interactions with unattached crown ethers [48]. Also, studies of diazo-4,7,13,16-tetraoxacyclooctadecane bound to polyacrylamide gel show an enhancement of cationic complexation when compared to ligands that are not bound to polymers [49]. On the other hand, polymer-bound crown ethers do not offer any advantage over unbound ligands in the Koening-Knorr reaction [50]. 

Recently, we have found that acrylamide derivatives such as N-methylacrylamide-(NMAAm) and N-methylmethacrylamide (NMMAm) were polymerized by radical initiators in adequate solvents to form polymer microspheres, which contained the very stable propagating radicals of the amide monomers in high concentrations. Furthermore, the living polymer radicals were found to react readily with other vinyl monomers at room temperature, yielding block copolymers. We have also investigated these reactions by means of ESR. This article reviews our recent work on the formation of living propagating radicals, their reactions with vinyl monomers, and their use in block copolymer synthesis. 

Figure 3.2 Reaction with vinyl ethers, (top with substituted vinyl ethers. A functional arrow) Nonfunctional termination (methylene group or fragment R is transferred onto the transfer) of a living ROMP with ethyl vinyl polymer chain end. ether, (bottom arrow) Functional termination...

Another new route of synthesis for soluUe polymer supports based not on the usual polymer-analogous derivatization but on the preparation of the support by copolymerization of functional monomers was outlined and demonstrated by Geckeler and Bayer [73,104]. They used radical copolymerization of amino acid alkenyl esters, which are easily accessible by a vinyl exchange reaction with vinyl acetate, with l-vinyl-2-pyrrolidinone as solubilizing comonomer for direct preparation of a functional soluble support [104]. Thus, a carrier soluble in water as well as in many or nic solvents was obtained which already contained the first amino acid residue of the peptide ... 

Jebrane, M., Sebe, G. A new process for the esterification of wood by reaction with vinyl esters. Carbohydr. Polym. 72(4), 657-663 (2008)... 

The kinetic order of the free-radical polymerization of some vinyl monomers can exceed a 1.5 power dependence on the monomer concentration. Such behavior is observed, for example, in the polymerization of VAc with azo-initiators [46, 58-62], To account for this high reaction order, Ito [58-62] proposed that, under high reaction temperatures and/or low monomer concentrations, the initiator radicals can also be involved in termination reactions with the polymer radicals. The chain initiation and propagation reactions of free and grafted polymer radicals, the chain transfer reactions with monomer and surface, and the termination reactions between polymer radicals remain identical to those given by Eqs (3)-(18). 

Alternately, the acetal-protected polymers have also been prepared by chemical modification on poly(vinylphenol) by reacting the polymer with vinyl ethers using PFTS as the catalyst. ile satisfactory results were obtained with chemical modification using methyl vinyl ether, the reaction with vinyl phenyl ether showed a low efficiency of blocking the phenolic groups as FT-IR studies indicated that the chemically modified polymer still showed some unprotected... 

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