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Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres
Thesis (MSc)--Stellenbosch University, 2024.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613882938294272 |
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| access_status_str | Open Access |
| author | Brown, Zoë |
| author2 | Lutz, Marietjie |
| author_browse | Brown, Zoë Lutz, Marietjie |
| author_facet | Lutz, Marietjie Brown, Zoë |
| author_sort | Brown, Zoë |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131608 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:12.690Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131608 Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres Brown, Zoë Lutz, Marietjie Matthews, Megan Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science. Polylactic acid -- Recycling Drug delivery systems Green chemistry UCTD Thesis (MSc)--Stellenbosch University, 2024. ENGLISH ABSTRACT: This study focused on upcycling post-consumer poly(lactic acid) (PLA) for potential use as a delivery system in cosmetic applications. Upcycling, a sustainable approach to managing plastic waste, involves transforming materials into products of higher quality or value than their original form. To explore this, methods were developed for synthesizing and characterizing PLA-based delivery systems commonly utilized in the cosmetic field, specifically PLA-based graft copolymers and microspheres. An amphiphilic graft copolymer was synthesized using an HA backbone with PLA side chains, forming a comb-like structure intended to create a gel-like consistency in an aqueous solution. The effect of PLA molecular weights of 5 000, 20 000, and 50 000 g/mol on grafting efficiency and graft copolymer behaviour in solution were studied. Characterization of the graft copolymers by proton nuclear magnetic resonance (¹H NMR) and dynamic light scattering (DLS) confirmed the formation of micelle-like structures in organic solvents. To confirm successful attachment, new graft copolymers with shorter HA backbones were synthesized and characterized using size exclusion chromatography (SEC) and diffusion-ordered NMR (DOSY NMR) in their tetrabutylammonium salt forms (HATBA-g-PLA). The DOSY NMR and SEC results indicated that there was preferential grafting of shorter PLA chains onto HA due to solubility and steric hindrance effects. The grafting of aloin onto PLA chain ends were synthesized using PLA molecular weights of 5 000, 20 000, and 50 000 g/mol. The characterization of both aloin and the PLA-conjugates was attempted, however, the presence of other compounds in the starting material complicated the process. The success of the grafting reaction could not be confirmed with certainty; therefore, no further testing was carried out on these products. PLA-based microspheres were fabricated using PLA samples of 20 000, 50 000 and 80 000 g/mol. Composites were made using cellulose and chitin as precursor materials, with a variation of the weight percent of 1.5, 2.5, 3.5 and 5 wt%. Each batch of particles made were loaded with aloin and HA, serving as the active cosmetic ingredient. While cellulose and chitin aimed to improve surface depression, scanning electron microscopy (SEM) revealed increased porosity with higher composite content. Aloin encapsulation resulted in dense structures with a significant decrease in porosity. Encapsulation efficiency for HA was difficult to determine via UV/Vis spectroscopy due to poor UV absorption. Application studies revealed the graft copolymer of the shortest PLA chain length (5 000 g/mol) to have superior moisture absorption capabilities. The moisture absorption tests conducted on the PLA-based microspheres indicated the signi?icant role of aloin to improve the properties of a PLA system. Encapsulation efficiency of aloin, in combination with particle morphology and moisture absorption properties, indicated the PLA-based particles loaded with aloin and made using 5 wt% of chitin in the precursor material to have the greatest potential as a cosmetic delivery system using post-consumer PLA of a higher molecular weight. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-01-29T06:55:04Z 2025-01-29T06:55:04Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131608 en Stellenbosch University xvi, 120 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Polylactic acid -- Recycling Drug delivery systems Green chemistry UCTD Brown, Zoë Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title | Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title_full | Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title_fullStr | Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title_full_unstemmed | Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title_short | Upcycling post-consumer poly(lactic acid) (PLA) forcosmetic delivery systems: Synthesis and characterizationof PLA-based graft copolymers and microspheres |
| title_sort | upcycling post consumer poly lactic acid pla forcosmetic delivery systems synthesis and characterizationof pla based graft copolymers and microspheres |
| topic | Polylactic acid -- Recycling Drug delivery systems Green chemistry UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131608 |
| work_keys_str_mv | AT brownzoe upcyclingpostconsumerpolylacticacidplaforcosmeticdeliverysystemssynthesisandcharacterizationofplabasedgraftcopolymersandmicrospheres |