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"Inverse vulcanisation" polymerisation of elemental sulphur with 1,3-diisopropenylbenzene; poly(sulphur-m-diisopropenylbenzene)

SyntheticPage 802
DOI: 10.1039/SP802
Submitted Oct 29, 2015, published Oct 29, 2015
Joseph Bear (joseph.bear.11@ucl.ac.uk), Charles Dunnill (c.dunnill@swansea.ac.uk)


			Reaction Scheme: <IMG src="/images/empty.gif">"Inverse vulcanisation" polymerisation of elemental <SPAN id=csm1446199121368 class=csm-chemical-name title=sulphur grpid="2">sulphur</SPAN> with <SPAN id=csm1446199390774 class=csm-chemical-name title=1,3-diisopropenylbenzene grpid="4">1,3-diisopropenylbenzene</SPAN><IMG src="/images/empty.gif">

Chemicals Used

Sulphur, S8 (≥ 99.5 %, Sigma Aldrich Ltd.).
1,3-diisopropenylbenzene (> 97 %, TCI).

Procedure

The following protocol is for 50 wt.% 1,3-diisopropenylbenzene poly(sulphur-m-diisopropenylbenzene):  Elemental sulphur (2 g, 7.81 mmol in terms of S8 units) was added to a 20 ml glass vial with a stirrer bar. Separately, an oil bath was heated to 185 °C and the vial containing the sulphur lowered into the bath carefully. Once melted and under vigorous stirring, 1,3-diispropenylbenzene (2.16 ml, 12.6 mmol) was rapidly injected and the two-phase mixture further agitated with a glass rod to ensure complete mixing. After 5 minutes, the mixture was poured into a silicone mould and placed in an oven at 200 °C for 30 minutes. After 30 minutes, the mould containing the polymer was removed from the oven and cooled to room temperature naturally giving the target compound, poly(sulphur-m-diisopropenylbenzene).

Author's Comments

  • Elemental sulphur melts at ca. 149 °C to give a red liquid, but if left in the oil bath between 149 - 185 °C tends to form intractable deep red oligomeric polysulphides which prevent effective magnetic stirring and mixing of the 1,3-diisopropenylbenzene. It is therefore desirable to avoid this phase by adding the sulphur directly to the oil bath at 185 °C.
  • Extra mixing with the glass rod is essential to ensure an homogeneous and high quality product.
  • The melting point and physical properties of the polymer can be tuned by altering the wt.% Sulphur : wt.% 1,3-diisopropenylbenzene ratio with melting point increasing with increasing 1,3-diisopropenylbenzene.
  • The polymer can be moulded into any shape and exhibits thermoplastic tendencies so can be re-melted and re-cast without loss of function- unusual as the accepted structure belies a thermoset polymer.
  • The synthesis should be conducted in a fume hood as obnoxious, low molecular weight sulphur containing organics are liberated during the reaction.

Data

Calc. for S16C20H24 (MW 777.44): C,30.90; H, 3.11; S, 65.99. Anal. Found: C, 35.85; H, 3.55; S, 56.17.

Lead Reference

J. C. Bear, W. J. Peveler, P. D. McNaughter, I. P. Parkin, P. O’Brien and C. W. Dunnill, Chem. Commun., 2015, 51, 10467–10470.

Other References

W. J. Chung, J. J. Griebel, E. T. Kim, H. Yoon, A. G. Simmonds, H. J. Ji, P. T. Dirlam, R. S. Glass, J. J. Wie, N. A. Nguyen, B. W. Guralnick, J. Park, Á. Somogyi, P. Theato, M. E. Mackay, Y.-E. Sung, K. Char and J. Pyun, Nat. Chem., 2013, 5, 518–524.

Supplementary Information

Melted and cast elemental sulphur with no 1,3-diisopropenylbenzene in "dog-bone" mould (yellow, top) and 50 wt.% 1,3-diisopropenylbenzene  poly(sulphur-m-diisopropenylbenzene) (red, bottom).
5 percent and 40 percent DIB S polymers in molds.jpeg

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Keywords: aromatics/arenes, inverse vulcanisation, polymerization, sulphides

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