Table 1 Carbon compositions of various RF resins.

From: Solar-to-hydrogen peroxide energy conversion on resorcinol–formaldehyde resin photocatalysts prepared by acid-catalysed polycondensation

Resin

Aromatics/% (c, d, e, g, h, i)

Linkers/%

Residual groups/%

Benzenoid /quinoida

Linker /aromatic ringb

Methylene ether (j)

Methylene (l, m, n)

Methine (f)

Ketone (b)

Aldehyde (a)

Methylol (k)

Methyl (o)

  

RF-NH3-523

59.8

2.1

24.5

4.6

0

5.0

2.4

1.7

54/46

3.02

RF-(COOH)2-523

68.1

0

18.5

5.0

0

4.7

2.1

1.6

51/49

2.07

RF-(COOH)2-523c

68.0

0

14.1

5.1

4.5

5.5

1.4

1.5

50/50

2.09

RF-(COOH)2-473

67.3

0

18.3

4.3

0

6.2

2.7

1.2

62/38

2.01

RF-(COOH)2-423

68.9

0

16.2

3.5

0

7.2

3.3

0.8

69/31

1.71

  1. The compositions were determined by integration of solid-state DD/MAS/13C NMR spectra (Fig. 5 and Supplementary Fig. 7). The letters in parentheses denote the corresponding carbons shown in the resin structure (Fig. 5).
  2. aMole fractions of quinoid and benzenoid units in resins were determined from respective peak areas using following equations:
  3. \(\begin{array}{l}\% {\mathrm{quinoid}} = \left( {\frac{{\left[ {{\mathrm{quinone}}\,C = {\mathrm{O}}\,{\mathrm{carbon}}\left( {\boldsymbol{c}} \right)} \right] \times 6 \times 100}}{{\left[ {{\mathrm{all}}\,{\mathrm{carbons}}\left( {{\boldsymbol{a}} - {\boldsymbol{o}}} \right)} \right]}}/[{\mathrm{all}}\,{\mathrm{aromatic}}\,{\mathrm{carbons}}\,({\boldsymbol{c}},{\boldsymbol{d}},{\boldsymbol{e}},{\boldsymbol{g}},{\boldsymbol{h}},{\boldsymbol{i}})]} \right) \times 100\\ \% {\mathrm{benzenoid}} = 100 - \% {\mathrm{quinoid}}\end{array}\)
  4. bRatio of number of linkers to number of aromatic rings in resins was determined using following equation: \({\mathrm{linker}}/{\mathrm{aromatic}}\,{\mathrm{ring}} = \frac{{\left[ {{\mathrm{all}}\,{\mathrm{linker}}\,{\mathrm{carbons}}\left( {{\boldsymbol{b}},{\boldsymbol{f}},{\boldsymbol{j}}/2,{\boldsymbol{l}},{\boldsymbol{m}},{\boldsymbol{n}}} \right)} \right]}}{{\left[ {{\mathrm{all}}\,{\mathrm{aromatic}}\,{\mathrm{carbons}}\,({\boldsymbol{c}},{\boldsymbol{d}},{\boldsymbol{e}},{\boldsymbol{g}},{\boldsymbol{h}},{\boldsymbol{i}})} \right]}} \times 6\)
  5. cRF-(COOH)2-523 resin recovered after photoreaction for 5 h in water with O2 using solar simulator (Fig. 4d).
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