Polymer from Scheme

4-Vinylbenzoic acid chloride [161, 162] (81.60 g 0.49 mol) in dry CH2CI2 (100 mL) was dropped into a solution of ethylamine (45.09 g 1.00 mol) in dry CH2CI2 (250 mL) at -20 °C. After it had been warmed to ambient temperature, phenothiazine (0.20 g) was added. The solution was stirred for 15 h. The precipitated ethylammonium chloride was filtered off and washed with a small amount of dry CH2CI2. The solvent was removed in vacuo and the residue recrystallized from EtOAc to give colorless crystals (172.4 g, 98%). 

Dry ethylammonium chloride (63.61 g 0.78 mol) was added to a solution of A -ethyl-4-vinylbenzocarboximide acid ethyl ester (121.97 g 0.60 mol) in dry EtOH (270 mL) under argon. After the mixture had been stirred at 15 °C for 5 h, 4-tm-butylbrenzcatechol (0.5 g) was added, the stirring was continued for five days at ambient temperature, and the solvent was removed in vacuo. The residue was treated with ice-cooled 6 m NaOH (500 mL) and directly extracted with an ice-cooled mixture of EtOAc/Et20 (1 1). The 

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Oxidation of the polymers from Scheme 1-66 leads to the polymeric cation radicals with ferromagnetic coupling of spins. Surprisingly, however, the spin concentration in these polymer networks was extremely low. Only a few percent of the cation radical units actually carried an unpaired electron. 

There are many different data analysis schemes to estimate the structure and molecular parameters of polymers from the neutron scattering data. Herein, we will present several connnon methods for characterizing the scattering profiles, depending only on the applicable q range. These methods, which were derived based on different assumptions, have... 

Extraction of hemiceUulose is a complex process that alters or degrades hemiceUulose in some manner (11,138). Alkaline reagents that break hydrogen bonds are the most effective solvents but they de-estetify and initiate -elimination reactions. Polar solvents such as DMSO and dimethylformamide are more specific and are used to extract partiaUy acetylated polymers from milled wood or holoceUulose (11,139). Solvent mixtures of increasing solvent power are employed in a sequential manner (138) and advantage is taken of the different behavior of various alkaUes and alkaline complexes under different experimental conditions of extraction, concentration, and temperature (4,140). Some sequences for these elaborate extraction schemes have been summarized (138,139) and an experimenter should optimize them for the material involved and the desired end product (102). 

The term epoxy is familiar to nonchemists because of the widespread use of epoxy glues and resins. These are crosslinked polyether thermoplastics made from a liquid resin which is typically a mixture of bisphenol A diglycidyl ether (70) and a polymer (71 Scheme 86). The liquid resin is cured or hardened to the final resin by mixing with a crosslinking reagent, which can be an acid, a di- or poly-alcohol, or a di- or poly-amine (Scheme 86). 

SCHEME 31.3 Generation of crosslinked and uncrosslinked polymers from monomers. 

It is quite clear from Schemes 2.1-2.5 that in rubbers polymer identification and additive analysis are highly interlinked. This is at variance to procedures used in polymer/additive analysis. The methods for qualitative and quantitative analysis of the composition of rubber products are detailed in ASTM D 297 Rubber Products-Chemical Analysis [39]. 

Catalyst Study. Equivalent amounts of p-phenylenebis(4,4-dimethyl-2-oxazol1n-5-one ) (2) and Jeffamine D-2000 (polyoxypropylenediamine from Texaco Chemical Co., amine equiv. weight 1023) were mixed with 5 mole % of the desired catalyst. The stirred mixture was heated at 240°C under argon for 30 minutes, then an additional 1.5 hours under vacuum (<1 torr) and collected. The amount of cyclization was estimated by 1H-NMR in CDC 13 by comparison of the Integrated intensities of the absorptions due to the gem-dimethyl substituents. These absorptions appeared at 1.39 ppm in the cyclic form and at 1.73 ppm in the open-chain form of the polymer (see Scheme 4). Results are listed in Table I. 

Paciorek et al. have investigated the direct formation of a polymer from the reaction of 2,4,6-trichloroborazine and hexamethyldisilazane.29,30 This one-step synthetic procedure also has been studied by Paine et al.31 The reaction in principle is depicted in scheme 5, and its main interest is that the driving force is the formation of stable and volatile Me3SiCl. 

Harada and coworkers proceeded further to obtain a tubular polymer from a PEG-a-CD polyrotaxane by using Scheme 2. The polyrotaxane was prepared... 

The rates of certain reactions of polymers have been reported to be enhanced by MW under homogeneous conditions at atmospheric pressure. Lewis et al. [64] performed kinetic studies on the imidization of the polymer BDTA-DDS polyamic acid 46 in N-methylpyrrolidone (NMP) giving the polymer 47 (Scheme 4.24) and showed that the apparent activation energy was reduced from 105 kj mol-1 under conventional heating to 55 kj mol-1 under MW heating. Rate enhancements (kMw/kthermai)... 

Tomalia et al. reported that the surface amines of PAM AM dendrimer can successfully react with methyl esters of other PAMAM dendrimers to afford core-shell tecto-(dendrimer) molecules [65]. Furthermore, they also reported the synthesis of rod-shaped cylindrical dendronized polymers from poly(ethyleneimine) cores without any crosslinking, albeit with the use of excess reagents [58]. These reports lead us to propose a new approach toward hybridized dendrimers and polymers (path C, Figure 15.3). As shown in Scheme 12,... 

When Paul Flory wrote his famous book Principles of Polymer Chemistry in 1952, he indicated an alternative scheme for polymer synthesis [1]. He theorized about synthesizing condensation polymers from multifunctional monomers. These polymers were predicted to have a broad molecular weight distribution and to be non-entangled and non-crystalline due to their highly branched structure. However, they were considered to be less interesting since they would provide materials with poor mechanical strength, and at that time Flory did not feel it was worthwhile pursuing this line of research. 

Extension of DKR to polymer chemistry would readily result in chiral polyesters, polycarbonates, or polyamides from an optically inactive monomer mixture. Scheme 10 describes three variants of chemoenzymatic catalysis applied in polymer chemistry that recently appeared in the literature. Route A uses AA and BB monomers to prepare chiral polymers from racemic/diasteromeric diols. Route B converts an enantiomer mixture of AB monomers to homochiral polymers. Route C is the enzymatic ring-opening polymerization of co-methylated lactones to homochiral polyesters. Details will be given in Sect. 3.4.2. 

Scheme 12 Chiral polymers from racemic co-methylated lactones by iterative tandem catalysis [105, 106]...

In the case of template polymerization, when reacting units are connected with the template by covalent bonds, analysis of the products can also be based on the separation of daughter polymer from the template. However, the covalent bonds should be broken for instance by hydrolysis of ester groups. This method was applied by Kammerer and Jung in order to prove that daughter polymer has the same number of units (plus end-groups) as the template. The scheme of the reaction can be represented as follows ... 

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