Sequential addition of propylene oxide

The hydrophobic central segment is first synthesized by sequential addition of propylene oxide to a propylene glycol initiator ... 

These materials were introduced by Wyandotte Chemicals Corp and are made by the sequential addition of propylene oxide and ethylene oxide to a low molecular weight reactive hydrogen compound [31]. The polypropylene oxide mid-block is water insoluble and acts as the hydrophobic part of the molecule in the same way as fatty alcohol in conventional ethoxylates. The addition of ethylene oxide to polypropylene oxide mid-block gives water soluble polyols having surface-active properties and the structure ... 

Block copolymers consisting of segments with widely separated solubility characteristics have generated considerable interest because of their unusual surfactant properties. In fact, one of the earliest commercial block copolymers were the Wyandotte "Pluronics." These were poly(propylene oxide-b-ethylene oxide) prepared by sequential addition of ethylene oxide to sodium alkoxide initiated propylene oxide (37,38). Szwarc (39) and others (40,41) prepared poly(styrene-b-ethylene oxide) by addition of ethylene oxide to polystyrene anions in tetrahydrofuran. Other syntheses of AB or ABA block copolymers of styrene-ethylene oxide include sequential addition in various solvents, and coupling reactions (42,43). 

Block copolymers of /3-PL and /3-BL have been synthesized using (251), although reaction times of several weeks are required.782 Since (TPP)Al-based carboxylates are also known to polymerize epoxides (see Section 9.1.7.2), the sequential addition of /3-BL and propylene oxide (PO) results in formation of a p(/3-BL-/3-PO) diblock.782 However, reversing the order of addition fails to produce the block copolymer since the propagating alkoxide (TPP)Al(OCHMeCH2)nCl does not initiate the ROP of /3-BL. 

Aluminum porphyrins have been used to prepare block copolymers by sequential monomer addition of two oxiranes [68, 318], of two )8-lactones [319], of a j5-lactone and an oxirane [319], of ethylene oxide and e-caprolactone [74] of propylene oxide and D-lactide [75], and of two methacrylates [76]. In the one example involving monomer pairs (j3-lactone and oxirane) which generate two different types of propagating species, the )8-lactone had to be polymerized... 

With dibutylzinc initiator and sequential polymerization, Bailey and France prepared block copolymers of ethylene oxide and epsilon-caprolactone and of propylene oxide and mixed methyl-epsilon-caprolactone (184). In these preparations, the poly(ethylene oxide) segments were formed first, followed by epsiloncaprolactone addition. 

A large variety of addition copolymers and terpolymers, prepared from hydroxyalkyl acrylates and/or methacrylates have been treated with MA to prepare polymers with pendent maleate residues.An addition polymer prepared from ethyl acrylate-hydroxypropyl methacrylate-styrene was treated sequentially with MA and propylene oxide.Blends of these polymers with vinyl monomers were cured with peroxides to obtain films with physical properties better than regular cured unsaturated polyesters. In another example, a styrene-butyl acrylate-hydroxyethyl methacrylate terpoly-mer was treated with MA to obtain a molding resin.When blended with styrene and cured with peroxides, the molding exhibited low shrink (less than 5%) and Rockwell hardness (M scale) 55. The same chemistry and technology have been explored for preparing radiation-curable coatings. " ... 

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