Polymers free-soluble

Related work was done with variously substituted acrylates in an ionic liquid 87). It was found that the solubility of both monomers and polymers depends on the chain length of the alkyl group linked to the ester. Methyl acrylate and its polymer are soluble in [BMIMJPF. However, butyl acrylate (BA) is only partially soluble, and the corresponding polymer is insoluble in the ionic liquid. The ATRP of BA in the ionic liquid proceeded under biphasic conditions with the catalyst, CuBr/pentamethyldiethylenetriamine, dissolved in the ionic liquid phase. Relatively low-molecular-weight polymer was formed. In this case, as the polymer was insoluble in the ionic liquid, it was spontaneously separated from the ionic liquid phase free of copper contamination. Furthermore, an undesirable side-reaction was significantly reduced in the ionic-liquid-phase ATRP 87). 

The principal polyolefins are low-density polyethylene (ldpe), high-density polyethylene (hope), linear low-density polyethylene (lldpe), polypropylene (PP), polyisobutylene (PIB), poly-1-butene (PB), copolymers of ethylene and propylene (EP), and proprietary copolymers of ethylene and alpha olefins. Since all these polymers are aliphatic hydrocarbons, the amorphous polymers are soluble in aliphatic hydrocarbon solvents with similar solubility parameters. Like other alkanes, they are resistant to attack by most ionic and most polar chemicals their usual reactions are limited to combustion, chemical oxidation, chlorination, nitration, and free-radical reactions. 

Kumar and Ramakrishnan demonstrated that the thermal decomposition (107 °C) of 3,5-dihydroxybenzoyl azide gave rise to the labile 3,5-dihydroxyphenylisocyanate, which afforded (at 110 °C in dry DMSO with a catalytic amount of dibutyltin dilaurate) the polyurethane in 95 % yield. The polydispersity is greater than two, which is indicative of the poor mobility of the monomers the polymers were soluble in aqueous base, confirming the presence of free phenolic termini. 

In view of thermodynamics the ceiling temperature looks like a melting point. Below and above this temperature the system consists of 100% polymer and of 100% monomer, respectively. This is shown in Fig. 20.2. If, however, the polymer is soluble in its monomer, then the free enthalpy of mixing also plays a role and the result will be that the "melting point" is not as sharp as shown there will be a gradual change (i.e. the dashed line) from 100% polymer to 100% monomer. The ceiling temperature is in this case defined as the temperature where the amount of monomer equals the amount of polymer (i.e. at 50%) and equal to (see, e.g. Ivin, 2000) ... 

The free-radical kinetics described in Chapter 6 hold for homogeneous systems. They will prevail in well-stirred bulk or solution polymerizations or in suspension polymerizations if the polymer is soluble in its monomer. Polystyrene suspension polymerization is an important commercial example of this reaction type. Suspension polymerizations of vinyl ehloride and of acrylonitrile are described by somewhat different kinetic schemes because the polymers precipitate in these cases. Emulsion polymerizations aie controlled by still different reaetion parameters because the growing macroradicals are isolated in small volume elements and because the free radieals which initiate the polymerization process are generated in the aqueous phase. The emulsion process is now used to make large tonnages of styrene-butadiene rubber (SBR), latex paints and adhesives, PVC paste polymers, and other produets. 

Both the monomer and polymer are soluble in the solvent in these reactions. Fairly high polymer concentrations can be obtained by judicious choice of solvent. Solution processes are used in the production of c(5-polybutadiene with butyl lithium catalyst in hexane solvent (Section 9.2.7). The cationic polymerization of isobutene in methyl chloride (Section 9.4.4) is initiated as a homogeneous reaction, but the polymer precipitates as it is formed. Diluents are necessary in these reactions to control the ionic polymerizations. Their use is avoided where possible in free-radical chain growth or in step-growth polymerizations because of the added costs involved in handling and recovering the solvents. 

Mass fraction solubility on a polymer-free basis. 

From this significant body of work, one can surmise that although incorporating fluorine into a compound may enhance its solubility in CO2, it is also necessary for the compound to be somewhat polar if high solubility in CO2 is to be obtained. Partial fluorination of a compound can lead to creation of dipoles, which enhance the solubility in CO2 owing to specific interactions with CO2. In addition, increases to polymer-free volume, based on choice of materials with substantial backbone flexibility, increases solubility in CO2. 

A latex-supported catalyst has been used to isolate sites. Styrene has been polymerized in the presence of an ionene diblock copolymer (a water-soluble cationic copolymer) to form a graft copolymer latex.31 The cobalt phthalocyanine sulfonate catalyst [CoPc(S03 Na+])4 was added and became attached to the cationic polymer. When this catalyst was used for the oxidation of thiols to disulfides by oxygen, the activity was 15 times that in a polymer-free system. 

Choice of Solvent. The most appropriate solvent for NMR studies of polymers would allow a range of polymer concentrations to be investigated, be free of overlap problems and hopefully provide a signal for internal lock. Not all of these conditions can usually be met as many high molecular weight polymers pose solubility problems and can be examined in only a limited number of solvents. Deuterium resonance is the typical choice for an internal lock signal on most modern NMR spectrometers. Unfortunately, the majority of available deuterated solvents are poor solvents for many addition polymers such as the polyolefins while it is generally possible to find a number of appropriate deuterated solvents for many of the condensation polymers. The... 

Polymer 56, soluble in DMF or DMSO, can be prepared by the condensation of amino-substituted [Ru(bpy)3]2+ with glyoxal [112]. This polymer showed weaker emission than the free Ru chromophore that was attributed to less efficient intersystem crossing to the 3MLCT state. Similar condensation reactions with diacid anhydrides to produce polyimides have been reported [113]. These polymers showed long-wavelength emission associated with charge-transfer states. 

Poly(acrylic acid) and poly(methacryKc acid) may be prepared by direct polymerization of the appropriate monomer, namely, acrylic acid or methacryhc acid, by conventional free-radical techniques, with potassium persulfate used as the initiator and water as the solvent (in which the polymers are soluble) or if a solid polymer is required, a solvent such as benzene, in which the polymer is insoluble, can be used, with benzoyl peroxide as a suitable initiator. 

Just like aciylonitrile, methacrylonitrile does not polymerize thermally but polymerizes readily in the presence of free-radical initiators. Unlike polyacrylonitrile, polymethaciylonitrile is soluble in some ketone solvents. Bulk polymerizations of methacrylonitrile have the disadvantage of a long reaction time. The rate, however, accelerates with temperature. The polymer is soluble in the monomer at ambient conditions... 

The hairy rod approach toward solubilized polymers of the PPP-type and the application of novel, sophisticated aryl-aryl coupling methods initiated an enormous progress in the field and today allow for the design of nearly defect-free soluble PPP derivatives of high molecular weight (up to 300,000 in the... 

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