Fluoro-type monomers

The synthesis of carboxyl end groups was explained by the fact that OH radicals may add onto the CF2, leading to intermediate FOCCH2. In the presence of water, this entity will become HOOCCH2 that will initiate a new chain and end up in a carboxyl end group. 

G represents a hydroxyl, hydroxymethyl or carboxylic function Y represents a hydroxyl or hydroxymethyl function 

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We examine the recent developments made in DEP conditions with monomers such as styrene, acrylates, fluoro-type monomers, and N-iso-propylacrylamide, with the aim of synthesizing telechelic oligomers. 

The authors also investigated unusual growth of hb poly(arylene ether)s using l,l,l-tris(4-hydroxyphenyl ethane as As-type and 5-fluoro-2-nitrobenzotrifluoride as BC-type monomer by one-pot synthesis with stepwise fluorine displacement followed by nitro displacement [75]. 

Lv et al. [201] designed and synthesized an AB2-type monomer, namely 4-fluoro-4, 4"-dihydroxy triphenyl methane. Through the homopolymerization of... 

The trifluoromethyl group can act as an effective activating group for fluoro displacement. Ghosh et al. synthesized a new trifluoromethyl-substituted AB-type monomer, namely 4-fluoro-3-trifluoromethylphenyl phenol [204], which was copolymerized with the AB2 monomer [ 197] in molar ratio 1 1 to yield a fluorinated hb copolymer by the AB -1- AB2 polymerization approach. The representative structure of the hb copolymer is shown in Scheme 18. The DB could not be evaluated from spectral analysis however, assuming a random copolymerization of the... 

A proposed mechanism for silyl ether displacement is shown in Scheme 6.14. In the first step, the fluoride anion converts the trimethyl siloxy group into a phe-nolate salt. In the following step, the phenolate anion attacks the activated fluoro monomer to generate an ether bond. The amount of catalyst required is about 0.1-0.3 mol%. Catalyst type and concentration are crucial for this reaction. 

Several other highly efficient coupling reactions have been reported to be of click in nature since they fulfilled all or some of the click chemistry criteria. Several types of metal-free click reactions have been developed. The more prominent ones are thiol-ene, thiol-yne, thiol-para-fluoro, hetero Diels-Alder (HDA) coupling reactions, and pyridyl disulfide exchange reactions (Scheme 8.6) [155-162]. Each of them requires specific initiators, monomers, and/or polymerization conditions. Therefore, the synthetic route should be carefully designed to prepare the desired functional polymers or solid substrates. 

Type 3 FKM These elastomers are made from VDF (vinylidene fluoride), TFE (tetrafluoroethylene), and PMVE (perfluoromethylvinylether), The added PMVE gives improved low-temperature performance compared to Type 1 and Type 2. This fluoro-elastomer, which is based on three different monomer units, typically possesses from 62 to 68 weight percent fluorine. 

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