| 1. |
- Cordova, A, et al.
(author)
-
Lipase-catalysed formation of macrocycles by ring-opening polymerisation of epsilon-caprolactone
- 1998
-
In: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 39:25, s. 6519-6524
-
Journal article (peer-reviewed)abstract
- Studies were undertaken to gain mechanistic information on lactone ring-opening polymerisation reactions using Candida antarctica lipase B (Novozym 435) as the catalyst and epsilon-caprolactone as the monomer. Polymerisations were performed in organic solvents as well as without solvent at 60 degrees C. Candida antarctica lipase B catalysed concurrently with the intermolecular ring-opening polymerisation, and also the formation of macrocycles by an intramolecular condensation reaction. Candida antarctica lipase B had the highest initial rate of consumption of epsilon-caprolactone (1.2 mu mol mg(-1) min(-1)) in the bulk polymerisation, without solvent. Under these conditions, the highest average M-w, 4701 D, of poly(epsilon-caprolactone) was obtained. There were small amounts of cyclic oligomers present. When comparing the polymerisations performed in dioxane, acetonitrile and THF after 24 h reaction time with the bulk polymerisation, the average M-w of poly(epsilon-caprolactone) [2984, 1297, 1862 D, respectively] and the initial rates of monomer conversion of the enzyme (0.1, 0.05, 0.013 mu mol mg(-1) min(-1), respectively) were lower, however, the formation of cyclic oligomers was high. In dioxane, macrocycles of up to 2623 D corresponding to 23 monomer units were formed, and in acetonitrile there were mostly cyclic oligomers present. (C) 1998 Elsevier Science Ltd. All rights reserved.
|
|
| 2. |
- Ek, R, et al.
(author)
-
Cellulose powder from Cladophora sp. algae
- 1998
-
In: JOURNAL OF MOLECULAR RECOGNITION. - : JOHN WILEY & SONS LTD. ; 11:1-6
-
Other publication (other academic/artistic)abstract
- The surface are and crystallinity was measured on a cellulose powder made from Cladophora sp, algae, The algae cellulose powder was found to have a very high surface area (63.4 m(2)/g, N-2 gas adsorption) and build up of cellulose with a high crystallini
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
