Functionally capped polyethylene

The original pin support was poly(acrylic acid) grafted onto inert polyethylene, where the carboxylic acid moieties were capped with mono Boc-protected ethyl-enediamine [79]. PS and the extremely hydrophilic polyhydroxyethyl methacrylate and poly(methacrylic add/dimethylacrylamide) were also grafted on [81]. The last grafted support in the Multipin concept is the so-called Lanterns [80], where the actual solid support is PS, which can be functionalized in a similar way to PS gel-type supports. 

The metallocene-ATRP route has been expanded by Matsugi etal. [164], to produce polyethylene-b-poly(methyl methacrylate). In the first step, hydroxyl-functionalized polyethylene was successfully prepared through the copolymerization of ethylene with aluminum-capped allyl alcohol, using a specific zirconium metaUocene/methylaluminoxane catalyst system. In the next step, the terminal alcohol was converted to hahde by 2-bromoisobutyryl bromide to obtain bromide-functionalized polyethylene, which could initiate the ATRP of MMA (Scheme 11.40). The block copolymers obtained exhibited unique morphological features that depended on the content of PMMA segment. Moreover, the block copolymers effectively compatibiUzed the corresponding homopolymer blend at the nanometer level. 

A typical example of the master curve [2] is shown in Figure 9.3 for HEUR (polyethylene oxide) end-capped with -C16H33. The reference temperature is chosen at 5 C. From the horizontal shift factor, the activation energy is found to be 67kJmol . From the high-frequency plateau of the storage modulus, the number of elastically effective chains is found as a function of the polymer concentration, which was already studied in Section 8.2 (Figure 8.10). 

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