PTMG

Mesogenic diols, such as 4,4 -bis( CO-hydtoxyaLkoxy)biphenyls, ate used with 2,4-TDI or 1,4-diisocyanatobenzene (PPDI) to constmct Hquid crystalline polyurethanes (7). Partial replacement of the mesogenic diols by PTMG shows that the use of lower molecular weight flexible spacers form polymers that have a more stable mesophase and exhibit higher crystallinity (8). Another approach to Hquid crystal polyurethanes involves the attachment of cholesterol to the polyurethane chain utilizing the dual reactivity in 2,4-TDI (9). 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

The third polyether PTMG is exclusively used for synthesizing polyurethanes which have superior properties to those synthesized from other polyethers, but its production is still limited because of the... 

These results suggest that PTMG is degraded via the oxidation process which is linked to an electron transport system of the bacterium. On... 

Figure 6. Degradation of PTMG 265 by Intact Cells of Alcaligenes denitrifjeans. HPLC was carried out with a flow rate of 1.0 ml/ min. The numbers in the fieure corresoond to monomer to hexamer. The first peak corresponds to inorganic phosphate.

Aoshima et al. (164) found that THF can be directly polymerized to give polyoxotetramethyleneglycol (PTMG) is a highly concentration solution of heteropolyacids [Eq. (16)]. 

The water content greatly influences the activity and the molecular weight of PTMG, as shown in Fig. 25. At the ratio of H2O/PW12O40 = 10, the reaction mixture consists of two liquid phases the upper phase is mainly THF and the lower phase is the complex of H3PW12O40 and THF (in the catalyst phase). The THF polymer is formed in the catalyst phase and is transferred to the THF phase. This phase-transfer polymerization is illustrated in Fig. 26. 

Fig. 15 SEM images of platelets adhered onto functionalised PE film surface a PE-AA, b PE-PTMG, c PE-POH, d PE-PCe...

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