The molecular weight M n of the star-shaped oligoLA polyol (l + m + n + o ¼ 14)
obtained by gel permeation chromatography (GPC) was 1,400 with M w /M n ¼ 1.4.
The polyol was shown to be amorphous by differential scanning calorimetry (DSC) and
had about 88% biomass content. The polyol was applied as a test coating on the
grip part of the Toyota personal mobility vehicle “i-REAL”; the coating was prepared
via two-component thermal curing with mixing the polyol and a polyisocyanate
hardener (Fig. 2) [44]. The biomass content of the cured coatings was 40 wt%.
The product, a star-shaped oligoLA modified with a methacryloyl group (S-OLAM1)
according to reaction (2) in Scheme 4, was of M n ¼ 2,600 and M w /M n ¼ 1.3, with
an average of 4.6 methacryloyl groups per molecule and a biomass content of 41 wt%
(63 wt% when succinic anhydride was counted as biomass). Instead of pentaerythritol,
dipentaerythritol also gave another S-OLAM (S-OLAM2). These S-OLAMs were
applied as UV-curable coatings. An example formulation was a mixture of S-OLAM2
(70 wt%), urethane hexaacrylate (30 wt%), and a photo-initiator (5 wt%). The film coating
was prepared by air-spraying on polycarbonate and then irradiating using a mercury
lamp to form the cured film, whose thickness was 15 μm. Performance data of the
UV-cured coating film indicated good initial adhesion, humidity resistance, alkaline
R OH
CH 3 CCO 2 H
OH
H
O
O
O
OH
HO
OH
OH
R O
OH
O
O
O
O
CH 3
O
H
O
O
H 3 C
O
H
CH 3
O
O
O
90 C
R O
O
O
O
CH 3
O
O
OH
C
O
O
C
O
CH 3
O
C
O
CH 3
O H
H
L-Lactic acid (LA)
Pentaerythritol
p-Toluenesulfonic acid
~175 C
- H 2 O
l
m
n
o
+
Star-shaped oligoLA polyol
(1)
(2)
4
Star-shaped
oligoLA polyol
Succinic anhydride
60
Triethylamine
4
Glycidyl methacrylate
p-Methoxyphenol
4
Star-shaped oligoLA modified with methacryloyl group
Scheme 4 (1) Synthesis of star-shaped oligoLA polyol from LA and pentaerythritol and
(2) synthesis of star-shaped oligoLA modified with methacryloyl group from the polyol, succinic
anhydride, and glycidyl methacrylate
150
S. Kobayashi
obtained by gel permeation chromatography (GPC) was 1,400 with M w /M n ¼ 1.4.
The polyol was shown to be amorphous by differential scanning calorimetry (DSC) and
had about 88% biomass content. The polyol was applied as a test coating on the
grip part of the Toyota personal mobility vehicle “i-REAL”; the coating was prepared
via two-component thermal curing with mixing the polyol and a polyisocyanate
hardener (Fig. 2) [44]. The biomass content of the cured coatings was 40 wt%.
The product, a star-shaped oligoLA modified with a methacryloyl group (S-OLAM1)
according to reaction (2) in Scheme 4, was of M n ¼ 2,600 and M w /M n ¼ 1.3, with
an average of 4.6 methacryloyl groups per molecule and a biomass content of 41 wt%
(63 wt% when succinic anhydride was counted as biomass). Instead of pentaerythritol,
dipentaerythritol also gave another S-OLAM (S-OLAM2). These S-OLAMs were
applied as UV-curable coatings. An example formulation was a mixture of S-OLAM2
(70 wt%), urethane hexaacrylate (30 wt%), and a photo-initiator (5 wt%). The film coating
was prepared by air-spraying on polycarbonate and then irradiating using a mercury
lamp to form the cured film, whose thickness was 15 μm. Performance data of the
UV-cured coating film indicated good initial adhesion, humidity resistance, alkaline
R OH
CH 3 CCO 2 H
OH
H
O
O
O
OH
HO
OH
OH
R O
OH
O
O
O
O
CH 3
O
H
O
O
H 3 C
O
H
CH 3
O
O
O
90 C
R O
O
O
O
CH 3
O
O
OH
C
O
O
C
O
CH 3
O
C
O
CH 3
O H
H
L-Lactic acid (LA)
Pentaerythritol
p-Toluenesulfonic acid
~175 C
- H 2 O
l
m
n
o
+
Star-shaped oligoLA polyol
(1)
(2)
4
Star-shaped
oligoLA polyol
Succinic anhydride
60
Triethylamine
4
Glycidyl methacrylate
p-Methoxyphenol
4
Star-shaped oligoLA modified with methacryloyl group
Scheme 4 (1) Synthesis of star-shaped oligoLA polyol from LA and pentaerythritol and
(2) synthesis of star-shaped oligoLA modified with methacryloyl group from the polyol, succinic
anhydride, and glycidyl methacrylate
150
S. Kobayashi