Polyurethane cationomers containing fluorinated soft segments with hydrophobic properties

Piotr Król,Kinga Pielichowska,Katarzyna Nowicka,Bożena Król,Małgorzata Kowal,Małgorzata Walczak

doi:10.1007/s00396-021-04819-4

Piotr Król, Kinga Pielichowska + Show 4 more

Open Access

https://doi.org/10.1007/s00396-021-04819-4

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Abstract

The synthesis of ecological waterborne polyurethane cationomers containing fluorinated polyol (0–20 wt.%) was successfully performed. FTIR and NMR analysis results confirmed the structure of the obtained polyurethane cationomers and incorporation of fluorinated component into the polyurethane chains. Average molar mass and phase structure of the obtained PU thin films were determined based on GPC, FTIR, WAXD and SEM-EDX results. The obtained cationomers have linear structures with clearly visible microphase separation of soft and hard segment domains; the presence of fluorinated polyol changes the strength of hydrogen bonds and in consequence degree of phase separation. The activation energy of glass transition was calculated based on multi-frequency DSC data. It has been shown that the presence of soft fluorinated segments in the cationomer structure strongly influences the hydrophobic, thermal and mechanical properties of the obtained films.

Highlights

Coatings and films based on polyurethanes modified with fluorinated compounds are currently subject of wide interest due to their hydrophobic character and unique properties [1,2,3,4,5]
Signals (a) of the protons of CH3-C groups confirmed incorporation of fluorinated diol into polyurethane structure (PU) chains, they are visible especially in 1H NMR spectra of PU20A, and signal (6′) refers to C atoms of -CH2–CF3 group observed in 13C NMR spectra in the range δ = 60 ppm
Incorporation of 5–15% fluorinated polyol as a soft segments in linear polyurethane cationomers synthesized using MDI or isophorone diisocyanate (IPDI) diisocyanate, poly(ε-caprolactone) diol (PCL) polyester and methyl diethanolamine (MDEA) amine leads to substantial changes on the strength of hydrogen bonds and in consequence degree of phase separation

Summary

Introduction

Coatings and films based on polyurethanes modified with fluorinated compounds are currently subject of wide interest due to their hydrophobic character and unique properties [1,2,3,4,5]. It is known that incorporation of fluorine atoms to polyurethane structure (PU) leads to weakening of intermolecular interactions and, in consequence, to changes in morphology due to significant decrease of phase separation [13] Such an effect makes the mechanical properties worsen, but improve the thermal stability and decrease the free surface energy (FSE). Due to the higher mass ratio of soft segments in polyurethane structure, it is expected that incorporation of fluorine atoms in polyol leads to formation of more hydrophobic polyurethane films and coatings with proper elastic properties typical for polyurethane-based elastomers. The open question is what kind of effect will be observed after the incorporation of fluorine-containing compounds to soft segments and how it will affect the thermal and mechanical properties of coatings and films based on polyurethane cationomers. Ð8Þ ms where: mm the mass of the wet sample after immersion in distilled water for 2 min, ms the mass of the dry sample before immersion

C The origin of the fragment atom structure

13 Urethane 13’ Urea

Results and discussion

Conclusions