Solubility homopolymers, copolymers

The same authors proposed an alternative methods for obtaining soluble poly(/i-vinylborazine) homopolymers and poly(styrene-co-B-vinylborazine) copolymers 28 In fact, gentle polymerization conditions in solution at 80°C using Azobisisobutyronitrile (AIBN) (1.6 mol%) as an initiator provided soluble homopolymers. The polymer displays typical Mw and Mn values of —18,000 and 11,000, respectively, whereas an increase in the AIBN concentration results in a decrease in the molecular weight, contrary to what is usually observed in free-radical polymerization. 

Bruno FF, Fossey SA, Nagarajan S, Nagarajan R, Kumar J, Samuelson LA (2006) Biomimetic synthesis of water-soluble conducting copolymers/homopolymers of pyrrole and 3,4-ethylenedioxythiophene. Biomacromolecules 7(2) 586-589... 

A reactive surfactant shown next (RS) was used as a comonomer in a seeded polymerization. RS was easily adsorbed on seed particles due to their amphiphilicity. If dialkyl fumarate was preabsorbed in the particle, the polymerization proceeded quickly and resulted in the formation of skin layer of RS-fumarate copolymer. Because the vinyl group in RS is an allyl type, RS in aqueous phase hardly polymerizes and no water-soluble homopolymer was formed. The active ester group of RS on the skin layer was used for the preparation of functional microspheres (18). 

Most dispersion polymerizations in C02, including the monomers methyl methacrylate, styrene, and vinyl acetate, have been summarized elsewhere (Canelas and DeSimone, 1997b Kendall et al., 1999) and will not be covered in this chapter. In a dispersion polymerization, the insoluble polymer is sterically stabilized as colloidal polymer particles by the surfactant that is adsorbed or chemically grafted to the particles. Effective surfactants in the dispersion polymerizations include C02-soluble homopolymers, block and random copolymers, and reactive macromonomers. Polymeric surfactants for C02 have been designed by combining C02-soluble (C02-philic) polymers, such as polydimethylsiloxane (PDMS) or PFOA, with C02-insoluble (C02-phobic) polymers, such as hydrophilic or lipophilic polymers (Betts et al., 1996, 1998 Guan and DeSimone, 1994). Several advances in C02-based dispersion polymerizations will be reviewed in the following section. 

Novel iron carbonyl monomer, r)4-(2,4-hexadien-l-yl acrylate)tricarbonyl-iron, 23, was prepared and both homopolymerized and copolymerized with acrylonitrile, vinyl acetate, styrene, and methyl methacrylate using AIBN initiation in benzene.70,71 72 The reactivity ratios obtained demonstrated that 23 was a more active acrylate than ferrocenylmethyl acrylate, 2. The thermal decomposition of the soluble homopolymer in air at 200°C led to the formation of Fe203 particles within a cross-linked matrix. This monomer raised the glass transition temperatures of the copolymers.70 The T)4-(diene)tricarbonyliron functions of 23 in styrene copolymers were converted in high yields to TT-allyltetracarbonyliron cations in the presence of HBF4 and CO.71 Exposure to nucleophiles gave 1,4-addition products of the diene group.71... 

Solubility Characteristics of Today s Vinyl Chloride Homopolymers, Copolymers, and Terpolymers... 

The polycondensation of difunctional oligomers leads to the preparation of well-defined polymer structures. Monomers in this type of reactions must be soluble in the reaction mixture and stable when the reaction is carried out in the melt, which is the case for some aromatic polymers prepared by polycondensation [22]. As previously described, polycondensation can occur with monomers bearing the same or a different functional group at both ends of the molecule. When one of the reactive functional groups is a hydroxyl moiety, several types of materials can be prepared, such as polyethers, polyesters, and polyurethanes, independently if they are used to form homopolymers, copolymers, or hyperbranched polymers. 

Imazato and co-workers [29,30] prepared a novel monomer, methacryloyloxydodecyl pyrimidinium bromide (MDPB). A water-soluble homopolymer of MDPB and copolymer of MDPB with acrylamide were also synthesised and the bactericidal activity against oral streptococci was studied. The mechanism of action of these quaternary compounds is assumed to be due to direct cationic binding to cell wall components, which results in disruption of the cell wall membrane, and subsequently results in leakage of critical cell contents and cell death. 

YAZ Yazici, D.T., Askin, A., and Butiiii, V., Thermodynamic interactions of water-soluble homopolymers and double-hydrophilic diblock copolymer, J. Chem. Thermodyn., 40, 353, 2008. 

The theory and experimentally structures exhibited by homopolymer-copolymer (A/A-B) blends were reported by De Gennes [111] and Gallot et al. [ 112] based on previous studies of Hashimoto et al. [113-115] who proposed a classification in terms of solubility of the copolymer brushes by the homopolymer. They established three different situations depending on the molecular weight of the homopolymers in the blend [113-115] (Fig. 5.15). They defined a situation (I) in which the homopolymer (generally a low molecular weight) can be completely or uniformly solubilized into the A block domains of similar chemical nature. In situation (II) the solubilization of the homopolymer in the block copolymer... 

Mayer, A. B. R. and Mark, J. E. CoUoidal gold nanoparticles protected by water-soluble homopolymers and random copolymers. European Polymer Joumal,34( 1), 103-108 (1998). 

Water-soluble homopolymers and copolymers are of high technical importance because of their wide-spread application in hydrogels, thickeners, viscosifiers, floccu-lants, membranes, coatings, etc. Mostly, these polymers are obtained from free-... 

Partly soluble triblock copolymers are also sometimes used for monolayer studies. Such investigations could provide data on desorption kinetics, and allow for comparison of the film structure, whether spread or adsorbed. However, attention should be paid to data interpretation in such cases because intricate equilibriums take place in such systems. A somewhat confusing study has been presented concerning the monolayer miscibility between PLA and PEO-PPO-PEO (also known as Pluronic) in monolayers [53]. The authors attempted to discuss interactions between the triblock copolymer and a homopolymer (PLA) on the basis of Langmuir monolayer experiments however, the results show unrealistic values for molecular areas, and therefore conclusions from those measurements cannot be quantitative. In particular, surface pressure-area isotherms for pure polymers and their mixtures reveal, in the compressed state, areas per monomer unit of the order of 3 h and below. Such low values cannot be real and most probably result either from material dissolution in the subphase or poor spreading at the air-water interface. Indeed, the isotherms do not appear smooth, which suggests low film stability and difficulties in forming a true monolayer. 

Figure 33 Solubility of copolymers and corresponding homopolymers in DM Ac with varying LiCI concentrations. 

Nonequimolar JV-vinyl-2-pyrrolidone-MA copolymers have had some study. The copolymers are generally prepared in the same manner as the homopolymers of the A-vinyl lactams and have similar properties with respect to water solubility. A copolymer containing 80% by weight of MA is a useful coating for water-dispersible particulate organic polymers. Such coated polymers have enhanced dispersibility in aqueous solutions with a minimum of agglomeration of the water-soluble polymer. " ... 

To act as possible "conductive bridges between adjacent CNTs, it would also be favorable when the metal NPs are in the vicinity of the CNTs. For this reason, a system in which the AuNPs are grown on the CNTs would be beneficial. This methodology also allows one to control the concentration of AuNPs in the final CNT dispersions. The inability to do this was shown to be the main disadvantage of the synthetic methodologies utilized in the previous section that dealt with QD-containing composites. An amphiphilic block copolymer or water-soluble homopolymer can be used both as a surfactant for the dispersion of individual CNTs, and as a template onto which AuNPs can be grown. 

It has also been exploited in the synthesis of phenylenevinylene polymers and copolymers. (Scheme 12.2). In general, these studies focused on the preparation of precursors that could be converted to insoluble phenylenevinylene homopolymer 8 (Thom-Csmyi et a/., 1993 Thorn-Csanyi and Pleug, 1993 Thorn-Csanyi et al., 1994), for example ROMP of (Friend et al, 1999) paracyclophane-1,9-diene 9 gives PPV as an insoluble, yellow fluorescent powder. Soluble phenylenevinylene copolymers have been prepared by ROMP of (Friend et al, 1999) paracyclophane-1,9-diene with cyclopentene, cyclooctene and cyclocta-1,5-diene comonomers (Thorn-Csanyi etal, 1993 Thorn-Csanyi and Pleug, 1993 Thorn-Csanyi et al, 1994). Unfortunately, the incorporation of more than 5% of phenylenevinylene units gives insoluble polymers, limiting the potential application of these materials. 

Figure 28 Solubility of copolymers and corresponding homopolymers in DMAc with varying LiCl concentrations (a) Copolymer of poly(p-benzamide) and poly(m-benzam-ide) (b) copolymer of poly (p-benzamide) and poly (ethylene glycol). Possible supramolec-ular organizations in the isotropic solution are schematized in the insert. (Reprinted with permission from Ref. 92. Copyright 1999, Wiley-VCH.)...

Oh, J.K., Perineau, F., Matyjaszewski, K. Preparation of nanoparticles of well-controlled water-soluble homopolymers and block copolymers using an inverse miniemulsion ATRP. Macromolecules 39(23), 8(X)3-8010 (2006)... 

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