Effects of Chemistries of Trifunctional Amines on Mechanisms of Michael Addition Polymerizations with Diacrylates

Abstract

The mechanisms of the Michael addition polymerizations of different trifunctional amines with an equimolar 1,4-butanediol diacrylate (BDA) were investigated by using 1H and 13C NMR to in situ monitor the polymerization processes. The trifunctional amine monomers adopted were 1-(2-aminoethyl)piperazine (AEPZ) and 4-(aminomethyl)piperidine (AMPD) and linear aliphatic amines with different steric hindrance on the 2° amines (original), i.e., N-methylethylenediamine (MEDA), N-ethylethylenediamine (EEDA), and N-hexylethylenediamine (HEDA). For AEPZ, AMPD, and MEDA with low steric hindrance on the 2° amines (original), the reactivity sequence of the three types of amines was 2° amines (original) > 1° amines ≫ 2° amines (formed) and linear poly(amino ester)s were formed via AB-type intermediates due to the 2° amines (formed) being kept out of the reaction. However, AB-type intermediates were only formed from the 2° amines (original) for AEPZ and AMPD, but from both the 2° amines (original) and 1° amines due to their smaller reactivity difference for MEDA. Nevertheless for EEDA and HEDA, the increased steric hindrance on the 2° amines (original) changed the reactivity sequence of the three types of amines to 1° amines > 2° amines (original) > 2° amines (formed) and branched polymers with degrees of branching of ca. 33% and 37%, respectively, were obtained due to all the three types of amines participating in the reaction. The molecular weights, glass transition temperatures, and thermal stability of the linear or branched poly(amino ester)s obtained were characterized by GPC, DSC, and TGA, respectively.

Michael addition polymerizations of trifunctional amines with diacrylamides

“…4-aminomethyl piperidine (AMPD), N-methyl ethylenediamine (MEDA), and 1-(2-aminoethyl) piperazine (AEPZ), with an equimolar diacrylamide. It is found that novel poly(amido amine)s containing secondary and tertiary amines in their backbones are formed as described in Scheme 1, similar to our results obtained for the Michael addition polymerizations of these trifunctional amines with an equimolar diacrylate [25,26]. These novel kinds of poly(amido amine)s are different from those poly(amido amine)s containing only tertiary amines in the backbones, on which Ferruti's group has carried out a systematic investigation [30].…”

“…In our previous work [25,26], we have found that the reactivity of trifunctional amines is unequal in the Michael addition polymerizations with diacrylates, and novel linear poly(amino ester)s applicable for safe and efficient delivery of gene are obtained. Nevertheless, the reactivity sequence of amines and the structures of polymers observed in our works are different from those reported for the polymerizations of trifunctional amines with divinyl sulfone or other diacrylates [27][28][29], so it is necessary to get understanding of the mechanisms of other polymerizations of this category.…”

Michael Addition Polymerizations of Trifunctional Amines with Divinyl Sulfone

“…Hence, the reactivity of the three types of amine in AEPZ has the following sequence: 28 amine (original) > 18 amine > > 28 amine (formed), which agrees with the conclusion in our previous work. [15,16] The difference of reactivity between 28 amine (original) and 18 amine is not so big enough to keep 18 amine intact during the Michael addition reactions. Thus, the reactions between groups A 2 (DVS) and B 3 (AEPZ) yielded a mixture of the addition products DVS-AEPZ and DVS-AEPZ-DVS intermediates at the very beginning of polymerization as shown in Scheme 1.…”

“…In the polymerization of this intermediate that is predominant in the polymerization system, the reactivity of the two B 0 amines is different. [15,16] Once one of the two B 0 groups reacts with vinyl groups, a new secondary amine formed can react with vinyl groups further. But its reactivity is much lower than that of the primary amine in AEPZ ring due to steric hindrance of polymer chains.…”

One-Pot Double Modification of Polymers Based on Thiolactone Chemistry

“…Therefore, selection of the reaction partners in this fundamentally challenging two-step reaction sequence is crucially important. Although maleimides react with both amines and thiols as Michael donor [124], acrylates are less reactive; at room temperature and without a catalyst, only secondary amines readily react with acrylates [125]. Hence, a reaction mixture of a primary amine, a thiolactone, and an acrylate in the absence of any catalyst results in the formation of the targeted conjugation product.…”