Dual mechanism bifunctional polymers

Figure 1. Chemical structures of the Class I, II, and III dual mechanism bifunctional polymers.

Bifunctional groups were also used to functionalize the St-DVB copolymer. The bifunctional polymers with two different ligands functionalized on the support were synthesized" in order to determine whether synergistic interactions between the ligands could lead to enhanced metal ion affinities and selectivities. These polymers were named dual mechanism bifunctional polymers (DMBPs) (Scheme 11.13)." °... 

The bifunctional initiator approach using reversible addition fragmentation chain-transfer polymerization (RAFT) as the free-radical controlling mechanism was soon to follow and block copolymers of styrene and caprolactone ensued [58]. In this case, a trithiocarbonate species having a terminal primary hydroxyl group provided the dual initiation (Figure 13.3). The resultant polymer was terminated with a trithiocarbonate reduction of the trithiocarbonate to a thiol allows synthesis of a-hydroxyl-co-thiol polymers which are of particular interest in biopolymer applications. 

Stereo-complex films were reported by Masutani et al7 % combining bifunctional PLLA and PDLA pre-polymers, multi-stereo-block copolymers having different block lengths and sequences are obtained. The resultant copolymers are readily fabricated into transparent films by hot-pressing. The films present excellent thermal stability and thermo-mechanical properties because of the easy formation of stereo-complex crystals. This synthetic method based on tbe dual terminal couplings allows obtaining stereo-block copolymers of PLLA and PDLA showing excellent thermo-mechanical properties and melt processability. 

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