Sustainable synthesis of renewable surfactants

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Goddard, Amy Rose (2016) Sustainable synthesis of renewable surfactants. PhD thesis, University of Nottingham.

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Abstract

This Thesis reports on the synthesis of novel surface active polymers using cyclic esters (D,L-lactide), dicarboxylic acids, oleochemicals and temperature sensitive polyols (D-sorbitol) as renewable building blocks. Product degradability, sustainability and low-toxicity are driving the demand for bio-based polymers and surfactants. Nonetheless, high processing temperatures (≥ 180 °C) and harsh post-reaction treatments are often needed in their synthesis, becoming a barrier to creating materials based on renewable resources.

The first systematic assessment of the chemo-selective synthesis of polyol-polyesters, prepared from D-sorbitol and aliphatic dicarboxylic acids using a carbonate catalyst is described herein. In this work, the effects of varying reagent concentrations and thermal conditions on product composition are compared with results using selective lipases (Novozym 435) and non-selective acid catalysts (pTSA). A clear distinction between the synthesis of linear, branched and ring closed compounds has been identified; the characterisation reinforced by phospholane derivatisation with subsequent 31P-NMR analysis. Moreover, the results demonstrated that linear polyol-polyesters can be competitive hydrophilic components in surfactant design when derivatised with hydrophobic oleochemicals.

In the synthesis of branched poly(D,L-lactide) using D-sorbitol as a core, supercritical carbon dioxide has been exploited as a green solvent to substantially reduce reaction temperatures, targeting controlled molecular weights with narrow dispersities and reduced side-product formation. Additionally, in the same pot, supercritical fluid extraction has been used to purify the compounds and to efficiently remove unreacted reagents, which can be recovered and recycled if required. The surface active properties of these branched materials have been evaluated, where modification of chain length and degree of branching provide a route to tailoring the properties and application performance of these new compounds.

In summary, the approaches describing the production and purification of novel surface active polyesters is an important contribution towards the development of the next generation of biopolymers and green surfactants. The developments discussed combine both the use of bio-sourced raw materials and the potential to use sustainable, low energy processes and techniques.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Howdle, Steve
Irvine, Derek
Keywords: polymers, surfactants, renewable, biobased, sustainable, supercritical carbon dioxide
Subjects: Q Science > QD Chemistry > QD450 Physical and theoretical chemistry
Faculties/Schools: UK Campuses > Faculty of Science > School of Chemistry
Item ID: 38715
Depositing User: Goddard, Amy
Date Deposited: 25 Jul 2024 12:37
Last Modified: 25 Jul 2024 12:51
URI: https://eprints.nottingham.ac.uk/id/eprint/38715

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