Poly PTMG

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. 

As shown in part A of Table IV, fg increases slightly with PTMG MW, while decreases. A similar trend was observed with low molecular weight polymers of poly(vinyl acetate) and polystyrene (6). It is reasoned that the molecular weight dependence of fg arises because longer soft segment length requires more volume to accommodate the increased number of conformations available to such a chain. 

The latter could be poly(tetramethylene glycol) (PTMG) or poly(ethylene glycol) (PEG). On the laboratory scale, as mentioned above, PEECs, which have also PCc as their soft segments, have been synthesized (Roslaniec et al, 1995). 

Until recently, the polyol component was restricted to poly(oxytetramethylene)glycol (PTMG), polycaprolactone diol and to adipate ester diols such as poly(ethyleneadipate)diol. The structures of these polyols are shown in Figure 2. 

Three of the block polymers were DuPont Hytrels 4055, 5555, and 6355 (17, 18, 19). These materials have a crystallizable PTMT hard block and a poly(tetramethylene glycol) (PTMG) soft block with a molecular weight of about 1000. Hytrels 4055, 5555, and 6355 contained about 42.6, 35, and 27% PTMG, respectively. The fourth polymer was Uniroyal TPR-19 which has a... 

A class of polymers fhaf has received considerable attention by researchers in fhe field of MALDI is fhe aliphatic polyefhers, with particular reference to poly(ethylene glycol), poly(propylene glycol), and poly(tetrameth-ylene glycol), abbreviated as PEG, PPG, and PTMG. It is well-known from sfudies with other ionization techniques (e.g., FAB, DCI, FD, LD, see Chapters 5, 6, 7, 8) that these polymers show a strong tendency to readily form ions in the gas phase. Some workers have analyzed PEG samples using FiABA to determine their MM, and obtained spectra with an excellent signal-to-noise... 

Materials. Hexamethylene diisocyanate (HDI) and dibutyl tin dilaurate (DBTDL) were purchased from Aldrich and were used as received. Sebacic acid (Aldrich), fumaric acid (BDH), and oxalic acid (Sigma) were dried ovemi t in vacuum at 60 prior to use. Poly(tetramethylene glycol) of molecular weight 2000 (PTMG, Polyscience) was dried overnight in vacuum at 80 °C before use. N,N-... 

Rg.19 Chemical structures of thermoplastic SMPs. (a) Aliphatic polyetherurethane TFX, which is prepared from methylene bis(p-cyclohexyl isocyanate) (H12 MDI), 1,4-butanediol (BD), and poly(tetramethylene glycol) (PTMG). (b) Multiblock copolymer PDC prepared from PPDO-diol, poly(p-dioxanone-diol) TMDl, 2,2(4),4-trimethylhexanediisocyanate PCL-diol, poly(f-caprolactone-diol). Reprinted by permission from ref. [85]. Copyright 2006, Nationtil Academy of Sciences, U.S.A. 

Because of the versatility of the polyurethane system it is possible to introduce comonomers which can affect the physical properties of the derived polymers. For example, photo cross-linkable polyurethanes are formulated using 2,5-dimethoxy-2,4 -diisocyanato stilbene as a monomer (76). Comonomers, having an azoaromatic chromophore, are used in optical bleaching applications (77), or in the formation of photorefractive polymers (78). The latter random poljnners have second-order nonlinear optical (NLO) properties. Linear poljnners are also obtained from HDI/PTMG and diacetylenic diols. These polymers can be cross-linked through the acetylenic linkages producing a network polymer with properties similar to poly(diacetylenes) (79). 

---