Cellulose- and Chitin-Based Coatings and Films. Carson Meredith Professor Chemical & Biomolecular Engineering Georgia Tech Atlanta, GA

Transcription

1 Cellulose- and Chitin-Based Coatings and Films Carson Meredith Professor Chemical & Biomolecular Engineering Georgia Tech Atlanta, GA 1

2 One Motivation - Packaging 1.3 billion tons of food, 1/3 of the world s production, is spoiled each year before it gets to a consumer s table food/beverage packaging market $276 billion 10% is flexible plastic 27% is rigid plastic Nearly all of these are petroleum-derived barrier plastics Chem. Soc. Rev. 2011, 40, Chem. Soc. Rev. 2014, 43, poly(ethylene terephthalate) (PET) poly(vinylidene chloride)) 2

3 Motivation 3

4 Other Motivations Composites Light-weight applications in transportation sector Futuris / American Process / Swinburne / Forest Products Laboratory / Clark Atlanta University Collaboration Adhesives Foams and porous materials Lightweighting Insulative Battery electrodes Futuris American Process GaTech CAU Swinburne USDA-FPL 4

5 Cellulose in wood and plant structures 5

6 Estimated cellulose nanocrystal Like carbon fiber, potential for highstrength but light-weight 6

7 Chitin 2nd most abundant polysaccharide ( tons each year) Structure similar to cellulose Ability to be functionalized Biocompatible Remarkable affinity to proteins Renewable Kohr E. Chitin: fulfilling a biomaterials promise. Elsevier Science,

8 Hierarchical architecture in nature Chitin Lobster exoskeleton Lobster exoskeleton: chitin and proteins assemble into hierarchical structures Exoskeleton consists of chitin nanofibers Acta Materialia 2005, 53:

9 Bio-derived gas barrier materials Q = vol / time A = area h Δp = pressure change Key figure is permeability, P P = DS P = Qh AΔp Units: [cm 3 µm m 2 d 1 kpa 1 ] 1 Barrer = [10 11 cm 3 cm cm 2 s 1 mmhg 1 ] 9

10 Bio-derived gas barrier materials High aspect-ratio composites used to increase diffusion path length Barrier P difficult to achieve defects at interfaces dispersion of filler Recyclability impacted Chitin and Cellulose nanofibers offer an advantage if used in neat form. 10

11 Bio-derived gas barrier materials Cellulose nanofibers show promise as barrier films P O2 = 0.17 cc um / m2 d kpa Untreated CNF P O2 = 0.01 cc um / m2 d kpa 175 C Treated CNF Nair, Zhu, Deng, Ragauskas Sustainable Chemical Processes 2014 Sharma et al., RSC Advances 2014 (Group of Prof. Yulin Deng) 11

12 Bio-derived gas barrier materials Only a few reports of barrier films involving chitin: Regenerated chitin films plasticized with glycerol P O2 = barrer (35 C) Journal of Materials Chemistry A 2013, Composite of chitin nanowhiskers coated on PLA P O2 = barrer International Journal of Biological Macromolecules 2012, 50, 69 No pure chitin films with high barrier properties (prior to our work) 12

13 Challenges for both cellulose and chitin in applications Insolubility Organic Solvents Atalla, R. H. and Isogai, A., in Polysaccharides : structural diversity and functional versatility,

14 Challenges for both cellulose and chitin in Insolubility applications Approaches to process cellulose / chitin Regeneration: dissolution followed by precipitation strong acids, bases or volatile organic solvents disrupts intrinsically high crystallinity Extraction and dispersion of nano-fibers Follow by assembly into film during drying Acid hydrolysis Peroxide oxidation (TEMPO) Grinding result in gelling suspensions Ultrasonication cannot extract most crystalline α form High-pressure homogenization Our approach Chitin nanofibers (ChNFs): Wu and Meredith Biomacromolecules 2014, 15,

15 Chitin Nanofiber Generation Crab shell Chitin purification: deproteination and dimineralization Purified chitin/water Chitin Mechanical nanofiber/water shearing dispersion 0.5 wt.% of chitin Purified chitin (micro-size particles) Chitin nanofiber (20 nm) (ph 4) Zeta potential curve of chitin nanofiber Wu and Meredith Biomacromolecules 2014, 15,

16 13 C CP-MAS solid state NMR of purified chitin from crab shells Degree of acetylation = 92.4% Wu and Meredith Biomacromolecules 2014, 15,

17 Morphology of Chitin Before homogenizer ph 4.1 ph 7.0 After homogenizer (35 passes) Wu and Meredith Biomacromolecules 2014, 15,

18 Rheological Properties of Dispersions ChNF/water ph of passes in homogenizer ChNF/water ph of passes in homogenizer Wu and Meredith Biomacromolecules 2014, 15,

19 Films from Chitin Nanofibers Wu and Meredith Biomacromolecules 2014, 15,

20 Mechanical Properties Chitin nanofiber (ChNF) Film Cellulose (CNC) Film Biomacromolecules 2014, 15, 4614 ACS Appl. Mater. Interfaces 2013, 5,

21 Gas permeabilities in ChNF films Gas Kinetic diameter (Å) Permeability (barrer) H CO O N CH % relative humidity Wu and Meredith Biomacromolecules 2014, 15,

22 ChNF Compared to Other Films P O2 (barrer) P C O2 (barrer) PE PP , 4 PET ChNF EVOH 1.5x10-5 CNF 1x % RH Duan et al. Journal of Materials Chemistry A 2013, 1, 1867 Gholizadeh et al. Mater. Des. 2007, 28, 2528 Jarus et al. Polymer 2002, 43, 2401 Tsai et al. Adv. Mater. 2005, 17, 1769 Wu and Meredith Biomacromolecules 2014, 15,

23 Chitin-based porous materials (a) (b) (c) 1 mm 1 µm Can we mimic and improve upon this intricate natural structure? 23

24 Freeze drying: freezing rate effect Starting materials: chitin nanofiber (20nm)/water dispersion Processing approach: Step 1. freeze this dispersion at different conditions: liquid nitrogen, -80 C, -20 C, -20 C (slow) (freezing rate: liquid nitrogen>-80 C >-20 C) Step 2. sublimation of ice crystals by freeze drier Pore size: 59.2±7.6 μm Chitin nanofiber (20nm)/water dispersion: liquid nitrogen freezing (sample bottom touched the liquid nitrogen) Wu and Meredith, ACS Macro Letters, 2014, 3,

25 Freeze drying: freezing rate effect Pore size: 59.2±7.6 μm Chitin nanofiber(20nm)/water dispersion: liquid nitrogen freezing Pore size: 96.2±12.0 μm Chitin nanofiber(20nm)/water dispersion: -80 O C freezing Wu and Meredith, ACS Macro Letters, 2014, 3,

26 Freeze drying: freezing rate effect Pore size: 3.2±0.4 μm Chitin nanofiber(20nm)/water dispersion: -20 C Enlarged top SEM image Wu and Meredith, ACS Macro Letters, 2014, 3,

27 CNC-Filled Epoxy with Meisha Shofner (MSE) Composites Xu, Girouard, Schueneman, Shofner, Meredith, Polymer,

28 Conclusions CNFs and ChNFs extracted via chemical/mechanical processes Formed direct into neat CNF or ChNF films Low permeability High transparency Good mechanical properties. Developed process for nanoporous chitin foams via freeze drying Useful for high-strength composites 28

29 Acknowledgements GT Renewable Bioproducts Institute USDA (Greg Schueneman) Jie Wu, former Ph.D. Student Natalie Girouard, current Ph.D. Student Michael Avidano, undergrad researcher Meisha Shofner, MSE 29