1 / 23

Motivation

Motivation. Nanocomposites: What are they? A Class of polymeric composites in which the filler materials are at the “nanometer” scale. Why are they important?

rhys
Download Presentation

Motivation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Motivation Nanocomposites: What are they? A Class of polymeric composites in which the filler materials are at the “nanometer” scale. Why are they important? They are known for their enhanced mechanical and other physical properties such as flame resistance. This is true even for very low filler contents, compared to the parent matrix. What are we doing with them? At present, proper understanding of microstructure-property correlations in nanocomposites is lacking. Using a block copolymer matrix and ‘wettable’ silica-type fillers with well-defined geometries, we generate a nanocomposite model system.

  2. Used block copolymers Polystyrene-b-polyisoprene PS-b-PI Polyisoprene-b-polyethyleneoxide PI-b-PEO

  3. Dissolution Synthesis of ‘hairy’ fillers The use of block copolymers as a structure directing agent allows synthesis of inorganic materials with well defined reproducible geometries and wettable surfaces.

  4. Rheometry Small angle X-ray scattering (SAXS) detector X-ray sample Experimental techniques • Data analysis in terms of: • Storage Modulus (G’) • Loss Modulus (G’’) • Loss Tangent (tand) • Peak Position (q*) • Peak Intensity (I(q*)) • Peak width (FWHM)

  5. Sol Gel Precursors Matrix and filler characterization Block copolymer matrix PS-b-PI • PS-b-PI diblock copolymer • Mn=20800 g/mol • PDI=1.06 • fPS=0.55 • Lamellar morphology • d=18.7nm Block copolymer template for fillers Fillers PI-b-PEO plates, d=21.4nm rods, d=22.0nm spheres, d=19.9nm

  6. Neat PS-b-PI copolymer SAXS Rheology SAXS: TODT =178°C Rheology: TODT =176°C

  7. Hybrid containing Spheres (0.5wt%) SAXS Rheology SAXS: TODT =167°C Rheology: TODT =166°C SFM image

  8. Hybrid containing long rods (0.5wt%) SAXS Rheology SAXS: TODT =153°C Rheology: TODT =159°C SFM image

  9. Hybrid containing short rods (0.5wt%) SAXS Rheology SAXS: TODT =161°C Rheology: TODT =163°C SFM image

  10. Hybrid containing large plates(0.5wt%) SAXS Rheology SAXS: TODT =163°C Rheology: TODT =164°C SFM image

  11. Hybrid containing small plates(0.5wt%) SAXS Rheology SAXS: TODT =162°C Rheology: TODT =162°C SFM image

  12. Conclusions • Addition of fillers (0.5wt%) leads to significant and complex changes in the order-disorder transition temperature, TODT, of the matrix block copolymer. • TODT is suppressed with increasing magnitude in the sequence: sph<lam<cyl. • Addition of the fillers causes a broadening of the transition temperature window in the sequence: sph<cyl<lam. • This is consistent with an increase of the peak width in SAXS as well as a broadening of the transition window observed in dynamic mechanical measurements.

  13. Hybrid containing spheres(5wt%) SAXS: TODT =175°C

  14. Hybrid containing short rods(5wt%) SAXS: TODT =173°C

  15. Hybrid containing long rods(5wt%) SAXS: TODT =175°C

  16. Hybrid containing small plates(5wt%) SAXS: TODT =169°C

  17. Hybrid containing large plates(5wt%) SAXS: TODT =145°C

  18. Hybrid containing spheres(0. 5wt%) SAXS: TODT =167°C

  19. Hybrid containing short rods(0. 5wt%) SAXS: TODT =161°C

  20. Hybrid containing long rods(0. 5wt%) SAXS: TODT =153°C

  21. Hybrid containing small plates(0.5wt%) SAXS: TODT =162°C

  22. Hybrid containing large plates(0. 5wt%) SAXS: TODT =163°C

  23. Comparison of TODT 0.5wt% 5wt%

More Related