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. 2022 Jun 29;14(13):2655.
doi: 10.3390/polym14132655.

A New Approach Utilizing Aza-Michael Addition for Hydrolysis-Resistance Non-Ionic Waterborne Polyester

Hao Fu  1 , Linbo Gong  1 , Shuling Gong  1
Affiliations

A New Approach Utilizing Aza-Michael Addition for Hydrolysis-Resistance Non-Ionic Waterborne Polyester

Hao Fu et al. Polymers (Basel). .

Abstract

This work first synthesized a series of linear polyesters by step-growth polycondensation, then an amino-terminated hydrophilic polyether was grafted to the polyester as side-chains through aza-Michael addition to prepare a self-dispersible, non-ionic waterborne comb-like polyester (NWCPE). In contrast to traditional functionalization methods that usually require harsh reaction conditions and complex catalysts, the aza-Michael addition proceeds efficiently at room temperature without a catalyst. In this facile and mild way, the NWCPE samples with number-average molecular weight (Mn) of about 8000 g mol-1 were obtained. All dispersions showed excellent storage stability, reflected by no delamination observed after 6 months of storage. The NWCPE dispersion displayed better hydrolysis resistance than an ionic waterborne polyester, as was indicated by a more slight change in pH value and Mn after a period of storage. In addition, the film obtained after the NWCPE dispersion was cross-linked with the curing agent, it exhibited good water resistance, adhesion, and mechanical properties.

Keywords: aza-Michael addition; comb-like polymer; hydrolysis resistance; non-ionic waterborne polyester.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
The synthesis route of comb-like polyester.
Figure 1
Figure 1
The 1H NMR of linear polyester (a), and comb-like polyester (b).
Figure 2
Figure 2
The FTIR spectrum and the second derivative spectrum of linear polyester and comb-like polyester.
Scheme 2
Scheme 2
The Ordelt reaction, cis and trans C=C bonds saturate with diol.
Figure 3
Figure 3
Effect of reaction temperatures on the isomerization extent and yield (a), Mn and Mw/Mn (b) of polyester.
Figure 4
Figure 4
Isomerization extent and yield (a), Mn and Mw/Mn of linear polyester (b) and comb-like polymer (c), particle size and viscosity (d) of polyester dispersions in different MA/(MA + HA).
Figure 5
Figure 5
Molecular weight and polydispersity for linear polyester (a) and comb-like polyester (b), DSC curves of comb-like polyester and part of cross-linked polyester (c), and average particle size of dispersions (d) in different CHDM content.
Figure 6
Figure 6
The ΔpH of dispersions (a), and ΔMn of comb-like polyester after storage for 6 months (b) in different CHDM content.
Figure 7
Figure 7
TG and DTG of NWCPE and cured polyester film.
Figure 8
Figure 8
Stress-strain profiles of cross-linked films.
Figure 9
Figure 9
The light transmittance (a), SEM image (b), and photograph (c) of cross-linked films.
See this image and copyright information in PMC

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