Polytetrahydrofurans, synthesis

A third example combines cationic ROP and ATRP for the synthesis of (polytetrahydrofurane)(poly-l,3-dioxepane)(PS) miktoarm stars (Scheme 99). The initiating sites for the above polymerization were created step-by-step from amino-succinic acid (Scheme 99). 

The synthesis of polystyrene-g-polytetrahydrofurane [188] was achieved by ATR copolymerization of methacrylic PTHF macromonomer, MA-PTHF, with styrene (Scheme 105). The PTHF macromonomer was synthesized by cationic ring opening polymerization of THF with acrylate ions, formed by the reaction of methacryloyl chloride and AgC104. The polydispersity indices of the graft copolymers determined by SEC ranged between 1.3-1.4. Kinetic studies revealed that the relative reactivity ratio of the macromonomer to St was independent of the molecular weight of PTHF. 

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. 

G. Hizal, A. Sarman, and Y. Yagci, Synthesis of hydroxy-terminated polytetrahydrofuran by photoinduced process. Polym. Bull. 1995, 35(5), 567-573. 

Quite recently, this intramolecular cyclization concept has been utilized for the synthesis of polytetrahydrofurans that occur in macrolides, iono-phores, and anti-infective agents. For example, cyclic sulfate 167 heated in aqueous acetonitrile gave polytetrahydrofuran 168 (95CEN41) (Scheme 40). A similar concept of intramolecular cyclization of a hydroxy group generated in situ has been used to prepare a trisubstituted tetrahydrofu-ran (93ACS307). 

Yoshida and Sugita [72, 73] have described the synthesis of polytetrahydrofuran (PTH F) possessing a nitroxy radical by terminating the Hving cationic ring-opening polymerization (CROP) of THF with sodium 4-oxy TEMPO. The polymer obtained in this way acted as a counter-radical in the polymerization of styrene, in the presence of a free radical initiator, to yield PSt-f)-PTHF (Scheme 11.16). 

Lu J., Liang H., Zhang R.F., Li B., Synthesis of poly(beta-pinene)-b-polytetrahydrofuran from beta-pinene-based macroinitiator, Polymer, 42(10), 2001, 4549 553. 

Common SS include polyethers, polyesters and polyalkyl glycols with glass transition temperatures in the range of -70°to -30°C. Commonly used macrodiols in the PUs synthesis are polyalkyl-diols, such as polyisobutylene diol [70], polybutadiene (PBU) [20, 71], or oligo-butadiene diols [72] as well as hydrogenated polybutadiene diol [20] polyether diols polytetrahydrofuran (PTHF or PTMO) [50-52], polyethylene glycol (PEG) or (PEO) [73], polypropyleneoxide (PPO) [73] or mixed blocks of them PEO-PPO-PEO [74] and PPO-THF [54] polyester diols poly(ethylene adipate) (PEA) [4,20], poly(butylene adipate) (PBA) [20, 73], and latterly polycaprolactone diol (PCL or PCD) [75], polyalkylcarbonate polyol [20] or mixed blocks of them, for example poly(carbonate-co-ester)diol [76], poly(hexamethylene-carbonate)diol [77], as well as poly(hexamethylene-carbonate-co-caprolactone)diol [78] and a mixed block copolymer of polyether and polyester blocks PCL-b-PTHF-b-PCL [79]. Examples schemes of macrodiols are shown in Eig. 1.9. 

In the PU synthesis we started from one mole of hydroxy-terminated macro-diol which was either a polyester type—polyethylene adipate (PEA) or a polyether type—polytetrahydrofuran (PTHF). 

Poly (thiophene)s are of particular interest as electfochromic materials owing to their chemical stability, ease of synthesis and processability. For the most part, current research has been focused on composites, blends and copolymer formations of several conjugated polyheterocyclics, polythiophene and its derivatives, especially PEIX)T. In one example, poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS) composite films were prepared by Sonmez et al. for alternative electrochromic applications [50]. Thin composite films comprised of PEDOT/PAMPS were reported to switch rapidly between oxidized and neufial states, in less than 0.4 s, with an initial optical contrast of 76% at A.max. 615 nm. Nanostructured blends of electrochromic polymers such as polypyrrole and poly(3,4-ethylenedioxythiophene) were developed via self-assembly by Inganas etal. for application as an electrochromic window [26]. Uniir etal. developed a graft-type electrochromic copolymer of polythiophene and polytetrahydrofuran for use in elecfiochromic devices [51]. Two EDOT-based copolymers, poly[(3,4-ethylenedioxythiophene)-aZ/-(2,5-dioctyloxyphenylene)] and poly[(3,4-ethylenedioxythiophene)-aft-(9,9 -dioctylfluorene)] were developed by Aubert et al. as other candidates for electrochromic device development [52],... 

The sol-gel synthesis of hybrid materials involves the occurrence of hydrolysis and condensation reactions in the presence of an organic polymer. Obviously, the selection of suitable polymer is of fundamental importance for the synthesis of the hybrid materials, as it should exhibit good miscibility with typical sol-gel precursors. The presence of suitable functional groups can facilitate the linkage between the polymer and the inorganic component. Also, the nature of the polymeric matrix is important because different properties of the matrix and, consequently, of the resulting nanohybrid material can be addressed for instance, the polymeric marix can be an elastomer (as in the case of polydimethylsiloxane) or thermoplastic (e.g., polytetrahydrofuran), amorphous, or (partially) crystalline [81]. 

Guo, Y.-M., Pan, C.-Y., and Wang, J. (2001). Block and star block copolymers by mechanism transformation. VI. Synthesis and characterization of A4B4 miktoarm star copolymers consisting of polystyrene and polytetrahydrofuran prepared by cationic ring-opening polymerization and atom transfer radical polymerization. J. Polym. Sci., Part A Polym. Chem., 59(13) 2134-2142. 

Feng, X.S. and Pan, C.Y. (2002) Block and star block copolymers by mechanism transformation. 7. Synthesis of polytetrahydrofuran/poly(l,3-dioxepane)/polystyrene ABC miktoarm star copolymers by combination of CROP and ATRP. Macromolecules, 35,2084—2089. 

Block polymers using blocks other than PROZO chain were prepared. As a typical example, polytetrahydrofuran (PTHF) was introduced to AB-type and BAB-type block copolymer as shown in Scheme 18. For the synthesis of the diblock copolymer, ethyl trifluoromethanesulfonate (EtOTf) was used as initiator, while for the triblock copolymer, anhydride of TfOH was employed, where a living CROP of THF end, an oxonium species, is involved. PTHF is a hydrophobic chain both copolymers showed very good surfactant properties, when MeOZO or EtOZO was used, as observed by the surface tension value reaching to y = 30.1-28.2. 

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