Poly hydroxyl terminated oligomers

Polyurethane (PU) PV membranes were reported by Schauer et al. (1999). PU membranes were prepared by the reaction of toluene-2,4-diisocyanate with hydroxyl-terminated oligomers. Oligomers were either liquid polybutadiene (PB) (MW 3000) or propylene oxide-based PEs (MW 420 and 4800). The prepared membranes were used in PV of binary mixtures of water-EtOH, water-dioxane, and EtOH-toluene, respectively. Membranes obtained from the polymer quatemized poly[3-(N, N -dimethyl)aminopropylamide-co-acrylonitriles] showed selective separation of water from aqueous EtOH solution by PV (Yoshikawa et al. 1991). The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. DSC melting endotherms of the water-swoUen membranes were studied to clarify the state of water in the membrane. The resnlts suggested that there were two states of water in the membrane bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was water permeated. 

Figure 6.8 shows the MALDI spectrum of the fraction of copolymer eluted at 27.9 ml. The MALDI spectrum of a fraction of copolymer eluted at 27.9 ml is well resolved and this allows the characterisation of the end groups. All the peaks were assigned to sodium alkoxide terminated oligomers of poly(EO-co-PO) copolymers. Nevertheless vinyl/hydroxyl and allyl/hydroxyl terminated oligomers with different ratios of EO to PO and, more unlikely, cyclic species are also possible. 

Copolymers incorporating a poly(phenyl silsesquioxane) chain have been described. Careful, low-temperature hydrolysis of trichlorosilanes yields hydroxyl-terminated oligomers [15], (XI-6) (21, 43). Reaction of [1 with a variety of difunctional silicon-containing monomers has given soluble copolymers. Polymerization of dimethyldichlorosilane in the presence of a preformed silsesquioxane block gave products possessing intrinsic viscosities of 0.17-0.29 (21, 43, 45, 47). A variety of other diehlorosilanes have been copolymerized in a similar fashion (43,45,47). 

Another approach was attempted by Seppala and Kylma who reported the synthesis of poly(ester-urethane)s by condensation of hydroxyl terminated tel-echelic poly(CL-co-LA) oligomers with 1,6-hexamethylene diisocyanate (Scheme 33) [94]. The diisocyanate acts as chain extender producing an increase in molecular weight of the preformed oligomers. The authors claim that some of the copolymers present elastomeric properties. Using a similar method. Storey described the synthesis of polyurethane networks based on D,L-LA, GA, eCL,... 

In conclusion, the hydroxyl terminated poly(arylene ether sulfone) oligomers of controllable molecular weight were synthesized by the NMP/K CO route. These oligomers were isolated and reacted in a second step with terephthaloyl chloride with or without added biphenol to form segmented copolymers. This second reaction was performed either in solution or interfacial-ly. It was found that the interfacial process allowed a higher percentage... 

From the T S/h) vs T h/r) plot for the curing reaction of hydroxyl-terminated poly(tetrahy-drofuran) lelechelic oligomer with styrene illustrated in Figure 3.18 at a heating rate of... 

The first application example is the electro-oxidative polymerization of phenol in the presence of 2,2-bis[3,5-dimethyl-4-hydroxyphenyl]-propane, which is the procedure to obtain terminally hydroxylated poly(phenyleneoxide), i.e. the oligomer contained two hydroxy groups per one molecule. 

Allyl alcohol, acting as a transfer agent, allows the terminal hydroxyl function to be obtained. The chain transfer constant of allyl alcohol was calculated to be about 2 x 10-2 towards poly(styryl radical). The authors used different monomers (Table 11) and always got functionalities close to 2, according to gel permeation chromatography (GPC) PS standards. Results in terms of conversion were excellent (above 70%). Oligomers were obtained with PDI around 1.8. 

In the same way, Oishi et al. [256] used IEM to functionalize oligomers carrying an acid function obtained by polymerization of chiral acrylamides. Chiral polyacrylamide macromonomers were synthesized from 2-methacryloyloxyethyl isocyanate and prepolymers, i.e., poly[(S)-methyl-benzyl acrylamide] or poly(L-phenylalanine ethylester acrylamide) with a terminal carboxylic acid or hydroxyl group. Radical homopolymerizations of polyacrylamide macromonomers were carried out under different conditions to obtain the corresponding optically active polymers, as shown in Scheme 52. 

In Chapter 3, the chemistry and technology of the most important oligo-polyols used for elastic polyurethanes fabrication, in fact high MW oligomers (2000-12000 daltons) with terminal hydroxyl groups and low functionality (2-4 hydroxyl groups/mol) were discussed. Polyalkylene oxide polyols (homopolymers of PO or copolymers PO - EO, random or block copolymers), polytetrahydrofuran polyols, filled polyols (graft poly ether polyols, poly Harnstoff dispersion - polyurea dispersions (PHD) and polyisocyanate poly addition (PIPA) polyols), polybutadiene polyols and polysiloxane polyols were all discussed. The elastic polyurethanes represent around 72% of the total polyurethanes produced worldwide. 

Linear poly(DVB) 11 is of synthetic interest because it can be functionalized through its terminal and in-chain unsaturation. Several examples of such functionalization, all examined recently in our laboratories, are shown in Eq. (15) These oligomers have varying numbers of hydroxyl groups of different nature, and are potentially useful as prepolymers or telechelic polymers. 

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