Effects and measurements of polyoxyethylene block length in polyoxyethylene‐polyoxybutylene copolymers

Abstract

Block copolymer surfactants, made from 1,2-butylene oxide (BO), propylene oxide (PO) and ethylene oxide (EO), exhibit wide ranges of properties and performance. In particular, BO/EO block copolymers exhibit improved surfactant performance with respect to PO/EO analogs. One interesting difference between these two classes of surfactants is the EO capping efficiency of polyoxypropylene {POP) vs. polyoxybutylene (POB) hydrophobe secondary hydroxyl groups. In this regard, nuclear magnetic resonance measurements have shown that POP secondary diols react more readily with EO than POB diols. For the case of ethoxylated POB polymers, the amount of unethoxylated secondary hydroxyl is proportional to the average length of the polyoxyethylene (POE) blocks. Differential scanning calorimetry was used to observe crystallinity of POE blocks. For a given POB hydrophobe molecular weight and weight percentage EO, surfactant performance properties can be augmented by affecting POE block length in the ethoxylation process.

Effects of block architecture and composition on the association properties of poly(oxyalkylene) copolymers in aqueous solution

“…A second, general effect arises because monomers such as PO and BO add to a growing chain to give secondary oxyanions, and slow initiation of the polymerisation of EO by a first-formed P or B block will result in a widened E-block distribution 46,47) . If the E-block is short (e. g. a 40 units in the formation of BE copolymers, a 13 units in the formation of PE copolymers) uncapped B or P ends will be present at the completion of the reaction 46,47) .…”

“…If the E-block is short (e. g. a 40 units in the formation of BE copolymers, a 13 units in the formation of PE copolymers) uncapped B or P ends will be present at the completion of the reaction 46,47) . In forming a triblock copolymer (EPE or EBE), uncapped ends imply a proportion of diblock copolymer.…”

Association of Triblock Copolymers of Ethylene Oxide and Butylene Oxide in Aqueous Solution. A Study of BnEmBn Copolymers

“…Considering the true triblock copolymers, the ranking order of N w for copolymers of a given 8 The effect of different reactivities is less pronounced for P end groups than for B end groups, but is important for short E-blocks, such as E 13 . 10 Accordingly, one would expect differences in critical micelle concentrations and association numbers to be small when comparing with the diblock and large when comparing with the P n E m P n triblock. Reported results confirm this conclusion; e.g.…”

Association Properties of a Diblock Copolymer of Ethylene Oxide and Styrene Oxide in Aqueous Solution Studied by Light Scattering and Rheometry

“…Any widening of the E-block length distribution caused by slow initiation in the second stage of polymerisation should be small for E 60 . [22,23] As described below, the study included characterisation of the copolymer by gel permeation chromatography (GPC) and 13 C NMR, of the micelles by dynamic and static light scattering, and of the gels by rheometry.…”