Hydroxide block polymers

OMPEO block polymers were synthesised by condensing dichlorometh-ane with a mixture of different molecular weight of PEG400 and 600 in the presence of potassium hydroxide powder. SPEs based on the OPMEO multi-block polymer were prepared. 

Weiss et al. [75] have synthesized Na and Zn salt of sulfonated styrene(ethylene-co-butylene)-styrene triblock ionomer. The starting material is a hydrogenated triblock copolymer of styrene and butadiene with a rubber mid-block and PS end-blocks. After hydrogenation, the mid-block is converted to a random copolymer of ethylene and butylene. Ethyl sulfonate is used to sulfonate the block copolymer in 1,2-dichloroethane solution at 50°C using the procedure developed by Makowski et al. [76]. The sulfonic acid form of the functionalized polymer is recovered by steam stripping. The neutralization reaction is carried out in toluene-methanol solution using the appropriate metal hydroxide or acetate. 

Thus, termination of oxazoline polymerization with potassium hydroxide gave hydroxy-terminated polymers, which in the presence of tin octoate were capable of initiating the anionic polymerization of -caprolac-tone [287] giving the corresponding block copolymer, acting as effective compatibiliser. 

In addition to the regular octahedral cluster core structure, there exists a rare example of an open, chair-like hexanuclear lanthanide hydroxide motif (Figure 6.39) in the hydrother-mally synthesized coordination polymers [Ln3((jL3-0H)2(BDC)3,5(H20)2] H20 (Ln = Y, Yb, Er BDC = 1,4-benzenedicarboxylate) [25,76]. The hexanuclear building block, consisting of six lanthanide ions and four p,3-OH groups, can be conveniently described as four edge-sharing units of [Ln3( X3-OH)]. 

Pluronic block copolymers are S3mthesized by sequential addition of PO and EO monomers in the presence of an alkaline catalyst, such as sodium or potassimn hydroxide (3). The reaction is initiated by polymerization of the PO block followed by the growth of EO chains at both ends of the PO block. Anionic polymerization usually produces polymers with a relatively low polydispersity index (Mn/Mw). Fmrther chromatographic fractionation was employed in procedures for the manufacture of highly purified block copolymers (12,13). 

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