To
develop biobased polyurethanes (PUs) via a less hazardous, nonisocyanate
route, herein we synthesize a series of biobased polyhydroxyurethanes
(PHUs) by reacting a new biobased cyclocarbonate (derived from renewable
diphenolic acid and carbon dioxide) with ethylenediamine (EDA), diethylenetriamine
(DETA), and isophoronediamine (IPDA), corresponding to PHU-EDA, PHU-DETA,
and PHU-IPDA, respectively. Their molecular structures are identified
from 1H NMR and FTIR analyses. Gel permeation chromatography
(GPC) analysis shows that the molecular weights of these PHUs grow
to as high as 5 kDa in a short reaction time (4 h) at a relatively
low reaction temperature (80 °C). Subsequently, the solvent-borne
(in acetone) coatings of these PHUs are successfully fabricated with
diglycidyl ether of bisphenol A as the cross-linker. The cured PHU
coatings on aluminum panels show the high pencil hardness (up to 4
H), adhesive force (up to grade 1), glass transition as high as 116
°C, and initial thermal degradation temperature up to 190 °C.
Furthermore, we realize the good dispersion of these PHUs in water
by introducing chemically bonded carboxylic anions into the molecular
backbone to form a stable aqueous emulsion with well-controlled particle
sizes and further demonstrate its application in a water-borne PHU
coating with good mechanical and thermal properties. Overall, we develop
a facile yet effective method to prepare sustainable, biobased PHUs
based on diphenolic acid and carbon dioxide via a safer, greener nonisocyanate
route and furthermore demonstrated their use as solvent-borne coatings
and greener water-borne coatings of reduced environmental impact.
Phenyl-centered tri-chain poly(ether-carbonate) (TMA-PEC), phenyl-centered double-chain poly(ether-carbonate) (TPA-PEC), and phenyl-centered fourchain poly(ether-carbonate) (TFA-PEC) were synthesized to act as CO 2 thickener. Their solubility in CO 2 was measured by cloud point pressure. In order
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