HEMA-lactate

HEMA dextran derivatized with HEMA-lactate... 

LE2 Lee, B.H. and Vernon, B., Copolymers of Y-isopropylacrylamide, HEMA-lactate and acrylic acid with time-dependent lower critical solution temperature as a bioresorbable carrier, Polym. Int., 54, 418, 2005. 

Poly(A/ -isopiopylacrylaniide-co-2-hydroxyethyl methaciylate lactate-co-acrylic acid) (84.4 tnol% NIP AM, 9.4 mol% HEMA lactate, 6.2 mol% acrylic acid)... 

First, L-lactide (2) is grafted onto HEMA (1), yielding HEMA-lactate (3). After activation with A,A -carbonyldiimidazole (GDI, 4), the resulting... 

HEMA-lactate-CI (5) is coupled to dextran (7) to yield dex-laetateHEMA (8) (Fig. 8). A comparable dextran derivative without lactate spacer between the methacrylate ester and dextran was also synthesized. For this compound, HEMA was activated with CDl, and the resulting HEMA-Cl (9) is then coupled to dextran, yielding dexHEMA (10) (Fig. 9). 

Interestingly, CDI can also be utilised for the introduction of substituents by inter- or intramolecular coupling of OH moieties of the polysaccharide via a carbonate function. This synthesis was used to obtain dextran with 2-hydroxyethyl methacrylate moieties (dex-HEMA) and dex-HEMA with lactate spacer functions (Fig. 32). A new class of dextran derivatives (DS < 0.2) that can be polymerised containing hydrolysable groups is accessible [177]. 

Figure 2 Schematic representation of the formation and degrad-tion for dex(lactate)HEMA hydrogels. Gels are formed by radical polymerization of the methacrylate groups using KPS and TEMED as initiator system. Degradation occurs by hydrolysis of the carbonate and lactate ester.

Figure 3 Cumulative release of IgG in time from dex-lactate-HEMA hydrogels (DS 10) with initial water content 90% (A), 80% (B), and 70 % (C). (From Ref 30.).

Figure 12. Swelling behavior of dex-HEMA ( ), dex-lactate-HEMA ( ) and dex-lactatej-HEMA (A) hydrogels in aqueous solution (pH 7.2, 37 °C). The initial water content of the hydrogels was 80%, the degree of methacryloyl substitution was approximately 6.

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