PNIPAm cross-linker

A cleavable, temperature-responsive polymeric cross-linker was utilized by Xu and cowoikers [111] to stabilize micelles from PEO-b-PAPMA-b-poly((Af,Af-diisopropylamino)ethyl methacrylate) triblock copolymer. The PNIPAm cross-linker contained activated ester end groups that were reacted with the primary amines on the PAPMA middle block. The trithiocarbonate moiety located at the middle of PNIPAm cross-linker could then be degraded by aminolysis to break the cross-links. Temperature-responsive micelles and vesicles from diblock and triblock copolymers were shell cross-linked via interpolyelectrolyte complexation [108, 112]. The cross-links formed by the electrostatic interactions of oppositely charged polyelectrolytes could be disrupted by the addition of SME. 

Recently, the effect of y-irradiation on the cross-linking of PNIPAm was evaluated applying 10-100 kGy doses in the presence and absence of the chemical cross-linker MBAAm (Munoz-Mufloz et al. 2012). The interpenetration of PAAc, the swelling degree, the amount of vancomycin... 

Figure 18 Size of PNIPAM microgels with different cross-linker content (increasing from top to bottom) vs. temperature. Reproduced with permission from Figure 1 in Senff, H. Richtering, W. ColloidPolym. Sci. 2000, 278, 830. ...

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