Copolyethers synthesis

Scheme 7. Synthetic avenues used for the synthesis of 4,4 -dihydroxy-biphenyl polyethers and copolyethers.

Scheme 6. Synthesis of Block Copolyethers with Regularly Placed Functional Groups.

Unfortunately, DMC catalysts are not efficient for EO polymerisation, and it is practically impossible to obtain PO-EO block copolymers with this catalyst. Acidic catalysts are not used on an industrial scale for alkylene oxide polymerisation due to the formation of substantial amounts of cyclic ethers as side products. Acidic catalysts are used industrially only for the synthesis of polytetrahydrofuran polyols or, to a lesser extent, for tetrahydrofuran - alkylene oxide copolyether polyol fabrication (see Sections 7.1, 7.2 and 7.3) Other catalysts have a minor importance for large scale polyether polyol production. 

Practically, the synthesis of random copolyethers of PO-EO is very similar to the synthesis of polyether PO homopolymers, with the difference that the starter (mainly glycerol) is reacted with an homogeneous mixture of PO-EO, containing around 10-15% EO, instead of PO alone. 

A very interesting group of random copolyethers is obtained by anionic copolymerisation of EO (a highly hydrophilic monomer) with BO (a highly hydrophobic monomer). Because EO does not isomerise to double bond structures and BO has a much lower tendency to isomerise to allyl structures than PO (see Chapter 12.2), the BO-EO copolyethers have a very low unsaturation level compared to PO homopolymers or even PO-EO copolymers [82]. This variant of polyether polyols synthesis in the form of BO-EO copolymers is a very interesting way to obtain low unsaturation polyether polyols directly from synthesis. Another group of low unsaturation polyether polyols, obtained directly from synthesis, are the tetrahydrofuran (THF)-EO and THF-PO copolymers synthesised with cationic catalysts (see Chapter 7.3). 

Scamporrino, E. and Ttalini, D., Main Chain Porphyrin Polymers. 2. Synthesis and Characterization of Some Copolyethers and Their Metal Derivatives, Macromolecules, 25, 6605, 1992. 

The goal of this paper is to review our present information on the synthesis and characterization of LC polyethers and copolyethers based on 4,4 -dihydroxy-a-methylstilbene (HMS) and 4,4 -dihydroxybiphenyl (HB) with a, (i)-dibromoalkanes. 

Table 2. Synthesis and Characterization of Polyethers and Copolyethers Based on 4,4 -Dihydroxy-a-methylstilbene, 1,5-Dibromopropane, and 1,7-Dibromoheptane... 

The experimental data concerning the synthesis and characterization of the copolyethers based on HB, 1,7-dibromoheptane and 1,9-dlbromononane are summarized in Table 5. In contrast to the copolyethers of HMS, which are all amorphous the copolyethers of HB are crystalline and present anisotropic melts exhibiting smectic textures. Examples of heating and cooling DSC scans for the copolymer PHB-7,9-20 are presented in Figure 9. 

Synthesis of irregular LC polyethCTS and copolyethers [24, 25] can be conducted by practically any method of polycondensation. p-Hydroxybenzoic, t ephthalic, and 2,6-naphthalenedicarboxylic acids and hydroquinone are used as the starting monomers which should form rigid anisometric units, and iso-phthalic and phthalic acids, resorcin, etc., can be used as the monomers containing linking atoms or oth perturbations of the linear direction of the change... 

Boulares A, RozSs L, Tessier M and MarSchal E (1998) Synthesis and characterization of poly(copolyethers-6-polyamides). I. Structural study of polyether precursors, J Macromol Sci - Pure Appl Chem A35 933-953. 

Boulares A, Tessier M and Mar chal E (2000) Synthesis and characterization of poly(copolyethers-6Zocfc-polyamides) II. Characterization and properties of the multiblock copolymers, Polr/mer 41 3561-3580. 

YE L, GAO p, WU F, BAI Y and FENG z G (2007c), Synthesis and application as polymer electrolyte of hyperbranched copolyethers derived from cationic ring-opening polymerization of 3-(2-(2-(2-methoxy- ethoxy)ethoxy)ethoxy)methyl- and 3-hydroxymethyl-3 -methyloxetane , Polymer, 48 1550-1556... 

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