Synthesis of hydrophobic weak-acid monomers by enzymatic action and their polymerization to obtain hydrophobic polyelectrolytes

Abstract

Abstract-We have prepared a series of carboxyalkyl methacrylates from the corresponding methoxy protected acids using pig liver esterase. From a set of these methacrylate derivatives with 3, 4, 5 and 7 methylenes as spacers, the enzymatic reaction exhibits a substrate selectivity for the terminal ester group of the molecule containing a short side-chain (3 methylenes); however, selectivity decreases as the length of the side-chain increases, resulting in partial cleavage of both ester groups in the methacrylates containing 4, 5 and 7 methylenes. This was probably due to the poor water solubility of the substrates, since the use of a tensoactive compound improved the selectivity of hydrolysis and yield. Furthermore, for side chains with 7 methylenes, hydrolysis of both esters groups is considerable (even in the presence of a tensoactive compound); therefore, the procedure is not recommended for highly hydrophobic molecules. Using the obtained carboxyalkyl methacrylates, polyelectrolytes were prepared by free radical polymerization. A pH-dependent phase-separation behavior was presented by the materials, making them suitable for applications in areas such as controlled drug release.

Well‐defined N‐Isopropylacrylamide Dual‐Sensitive Copolymers with LCST ≈38 °C in Different Architectures: Linear, Block and Star Polymers

“…An acid comonomer with a p K a value higher than that of acrylic acid (AA) or methacrylic acid (MA) was needed given the fact that the LCST of copolymers of NIPAAm with AA or MA are to high at pH 7-8. [ 21 ] We have chosen three acid comonomers with p K a values between 5 and 6, namely, 5MPA with p K a = 6.14, [ 57 ] 4MBA with p K a = 5.3 [ 56 ] and 2MBA with p K a = 5.8. [ 56 ] Furthermore, all three acid comonomers contain hydrophobic moieties as spacer groups (see Figure 1 ).…”