Synthesis of photocrosslinkable polyesters by the Knoevenagel reaction

Abstract

SynopsisA new group of photocrosslinkable polyesters formed by the Knoevenagel reaction is described. The approach permits preparation of photoesensitive polymers, where physical properties can be potentially vaned through choice of the polyol and the dicarboxylic acid.(1) products from a Knoevenagel reaction of poly(trimethylo1propane azelate cyanoacetate) with benzaldehyde, furaldehyde, and 2-ethylbutyraldehyde and ( 2 ) products from a Knoevenagel reaction of poly( 1,3-propyl malonate) with benzaldehyde, pmethoxybenzaldehyde, and Zethylbutyraldehyde. Conventional unsaturated polyesters such as poly( 1,3-propyl fumarate) and poly(l13-propyl maleate) were prepared and used for comparison.The following compounds were prepared and studied:

Enzyme-catalyzed synthesis of malonate polyesters and their use as metal chelating materials

“…34 One of the few available reports on malonate polyesters is the P 2 O 5 -catalyzed synthesis of poly(1,3-propyl malonate), but also in this case the obtained molecular weights were really limited since the maximum achieved DP was approximately 5. 13 Taking inspiration from recent papers on environmentally friendly synthesis of polymers, and due to the impossibility to obtain polymers using traditionally-used methods, an enzymatic approach was used in order to synthesize a series of malonate-containing aliphatic polyesters using diols having a chain length from 4 to 8 carbon atoms. For the synthesis performed in this work, an immobilized preparation of Candida antarctica lipase B (iCaLB) was used as the biocatalyst since this enzyme was reported to be an excellent candidate for such synthesis reactions.…”

“…The signals at 3.38 ppm (C-CH̲ 2 -C of the malonate) and in the 1.3-1.8 ppm range (-CH̲ 2 -CH 2 -OH of the diols) do not noticeably change chemical shift upon elongation of the polymer chain. 13 C-NMR spectroscopy of the polymer reveals the typical signals for these aliphatic polyesters (Fig. S6 in ESI †).…”

“…12 To the best of our knowledge, malonate-derived polyesters were reported before in the literature only in the form of short oligomers having a maximum DP of around 5. 13 In fact, the reports dealing with malonate polymers describe mainly the synthesis of aliphatic hyperbranched polyesters (HBPE) from various monomers derived in one step from commercial diethyl malonate. 14 The acidand metal-catalyzed polycondensation of malonate derivatives bearing aliphatic residues 15 was also reported together with the sequential anionic polymerization of ethylene oxide and methylidene malonate to obtain poly(ethylene oxide)-blockpoly(methylidene malonate 2.1.2) block copolymers bearing a primary amino group at the PEO chain end.…”

“… 34 One of the few available reports on malonate polyesters is the P 2 O 5 -catalyzed synthesis of poly(1,3-propyl malonate), but also in this case the obtained molecular weights were really limited since the maximum achieved DP was approximately 5. 13 …”