NIPAM functionalized, synthesis

The synthesis of block copolymers by macromonotner RAFT polymeriza tion has been discussed in Section 9.5.2 and examples are provide in Table 9.9. RAFT polymerization with thioearbonylthio compounds has been used to make a wide variety of block copolymers and examples arc provided below in Tabic 9.28. The process of block formation is shown in Scheme 9.59. Of considerable interest is the ability to make hydrophilic-hydrophobic block copolymers directly with monomers such as AA, DMA, NIPAM and DMAEMA. Doubly hydrophilic blocks have also been prepared.476 638 The big advantage of RAFT polymerization is its tolerance of unprotected functionality. 

Thermally responsive polymers, such as poly( V-isopropyl acrylamide) (NI-PAm), have also been studied extensively for applications related to those previously discussed [112], De las Heras et al. described the synthesis and patterning of NIPAm brushes on SAMs and their subsequent performance during temperature-dependent adhesion assays of BSA and Streptococcus mutans (Fig. 7). The authors employed p.CP to pattern features of hydrophobic hexadecanethiol and backfilled the surface with an initiator-functionalized alkanethiol. Polymer brushes were grown via surface-initiated atom transfer radical polymerization (ATRP). FITC-BSA was then... 

Recently, this combination was also used in the synthesis of double-hydrophilic block copolymers such as PEO-l -PNIPAM and PEO-l -PSS. In these applications, the hydroxyl groups of mono- or difimctional PEOs were converted to dithiobenzoyl groups and used as macro-RAFT agents. Depending on the functionality of the initial PEO-, AB-, and ABA-type block copolymers, well-defined structures were prepared from the polymerization of NIPAM and styrenesulfonate (SS). The overall procedure is summarized in Scheme 45. 

In a recent example, Maynard and coworkers demonstrated the synthesis of a Boc-protected aminooxy functionalized initiator for copper(i)-mediated ATRP of NIPAM (Figure 1.8). Deprotection of the polymer end groups... 

Wong and coworkers have investigated the enzymatic oligosaccharide synthesis on a thermoresponsive polymer support (Scheme 16.33). The copolymers of 7V-/-propyla-crylamide (NIPAm) and functionalized monomers are thermoresponsive and exhibit inverse temperature-dependent solubility in water they are soluble in cold water but become... 

There are numerous reports in the literature describing the synthesis of low polydispersity PNIPAm (co)poly-mers via CRP methods. For example. Binder et al. [54] described the synthesis of telechelic PNIPAm using functional NMP initiators modified via azide-alkyne cycloadditions. Efficient block copolymerization of NIPAm with styrene was achieved via sequential polymerization initiated by a-hydrogen alkoxyamine [55]. A PNIPAm block was first prepared and then chain extended with styrene yielding amphiphilic diblock copolymers. Initial attempts to use ATRP to prepare PNIPAm resulted in polymers with broad polydisperisities [56], but this problem was circumvented by utilizing a more efficient ligand for the initiator complex [57]. 

---