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Solid-state NMR to quantify surface coverage and chain length of lactic acid modified cellulose nanocrystals, used as fillers in biodegradable composites

Sofie Gårdebjer (Institutionen för kemi och kemiteknik, Farmaceutisk teknologi ; SuMo Biomaterials) ; Anna Bergstrand (SuMo Biomaterials ; Institutionen för kemi och kemiteknik, Farmaceutisk teknologi) ; Alexander Idström (Institutionen för kemi och kemiteknik, Teknisk ytkemi ; SuMo Biomaterials) ; C. Borstell ; S. Naana ; Lars Nordstierna (Institutionen för kemi och kemiteknik, Teknisk ytkemi ; SuMo Biomaterials) ; Anette Larsson (Institutionen för kemi och kemiteknik, Farmaceutisk teknologi ; SuMo Biomaterials)
Composites Science And Technology (0266-3538). Vol. 107 (2015), p. 1-9.
[Artikel, refereegranskad vetenskaplig]

The surface of cellulose nanocrystals (CNC) was chemically modified with polylactic acid. The modification was characterized by infrared spectroscopy, by monitoring the colloidal behavior of CNC in different solvents, and by quantitative analysis using solid-state NMR (ss-NMR). The quantitative analysis showed that grafted PLA chains on average comprised two lactic acid units attached to 48% of all available hydroxyl groups on the surface of the CNC. Both modified and unmodified CNC were incorporated as fillers in three different biodegradable materials: polylactide acid (PLA), poly(lactide-co-glycolide) (PLGA) and poly(3-hydroxybutyrate) (PHB). Composite films with up to 20 wt% of unmodified and modified CNC were produced via solvent casting. Compared to unmodified CNC, the modified CNC showed less aggregation in organic solvents and hydrophobic polymer materials and increased interaction was seen between the polymer and filler after surface modification. Using ss-NMR, our study shows that even as little as two units of PLA assures stabile CNC dispersions in organic solvents and distribute CNC in hydrophobic polymers.

Nyckelord: Nanocomposites, Thermal properties, Solid-state NMR



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Denna post skapades 2015-03-26. Senast ändrad 2016-11-07.
CPL Pubid: 214376

 

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