Ústav makromolekulární chemie AV ČR, v.v.i.


Vzdělávací a informační středisko ÚMCH AV ČR, v.v.i. každoročně pořádá celoústavní konferenci "KOLOKVIUM" zaměřenou na prezentaci nejvýznamnějších výsledků výzkumných programů řešených
na našem ústavu v daném roce.



HOSTÉ  Z  JINÝCH  INSTITUCÍ         (Kolokvium  2010)

Josef JančářProf. RNDr. Josef Jančář, CSc.

Fakulta chemická Vysokého učení technického v Brně

Název přednášky:

The role of chain-nanoparticle interactions in synthetic and bio-based nanocomposites

Abstrakt přednášky:

The control of the performance of polymer composites can be excercised at various length scales. Properties of the constituents, their content and spatial arrangement and the 3D-interphase phenomena are the main variables at the micro-scale. It seems possible to consider an additional length scale in the design of future polymer composites to achieve composite structures capable of signaling their integrity status and capable of self repair locally by taking advantage of the nano-scale materials design. This approach simulates, to some extent, multiscale structure of biocomposites such as wood, bones and shells. The hierarchical structure and multifunctional performance of biocomposites is controlled at the various length-scale interfaces between the individual structural levels. Unlike at the micro-scale, where the 3D-interphases existing between the individual components is considered continuous, at the nano-scale, the interphase phenomena must be considered at the length scales corresponding to the dimensions of individual molecules.

Effect of the type and strength of chain-particle interactions on the manifestation of interphase phenomena will be reviewed and some aspects of the principal differences between the role of interface/interphase phenomena as affected by the dimension scale from 10-6 m to 10-9 m. In order to provide experimental background for understanding micro-scale interphase, thickness dependence of elastic moduli of thin organic layers deposited on solid glass surfaces will be discussed. Effects of molecular structure and type of surface interactions on the elastic moduli of these layers will be described. An attempt will be made to correlate the obtained data with the results of the single embedded fiber fragmentation tests.

Further, temperature and composition dependeces of elastic moduli of model nanocomposites containing particles of varying shape with smilar specific surface area of approximately 150 m2/g will be interpreted using chain reptation dynamics approach to describe the molecular reinforcing mechanism at the nano-scale and the controlling role of the area of contact between the matrix and the reinforcement. A "hybrid" approach to bridge the micro-scale continuum mechanics models with the nano-scale discrete chain dynamics models will be demonstrated to provide means for transforming mechanical response of a polymer composite accross the individual length scales from nano- to macro-scale. Potential applicability of the models derived for synthetic hierarchical composites in mechanics of hard tissues will be discussed.

Curriculum vitae

Professor of Macromolecular Chemistry
Adjunct Professor, Polymer Program, University of Connecticut, USA
Director, Institute of Materials Chemistry, Brno University of Technology, CZ

RNDr. (1983) Masaryk University Brno, CZ (solid state physics)
CSc (1988) Czech Academy of Sciences, Prague, CZ (macromolecular chemistry)
Associate Professor, University of Connecticut, USA (1992) (polymer science)
Associate Professor, Brno University of Technology, CZ (1994) (macromolecular chemistry)
University Professor, Brno University of Technology, CZ (1997) (macromolecular
chemistry) Adjunct Professor, Polymer Program,UCONN, USA (1999-) (polymer science)

Awards: Czech Society for Sciences 2000 Senior Award
Publications: 162 papers in impacted journals, 8 books, 12 chapters in books, 7 patents
Research interests: Heterogeneous polymer systems, deformation behavior and fracture phenomena, interphase/interface phenomena, nanocomposites, biomaterials

Recent papers relevant to the proposed project:

  1. Jancar, J (2006), Hydrolytic stability of PC/GF composites with engineered interphase of varying elastic modulus. Composites Science and Technology 66: 3144 - 3152
  2. Jancar, J (2006), Effect of interfacial shear strength on the mechanical response of polycarbonate and PP reinforced with basalt fibers. Composite Interfaces 13: 853 - 864
  3. Zidek J., Jancar J (2006), Simulation of Inelastic Stress Strain Response of nanocomposites by a Network Model. Key Engineering Materials 334-335: 857 - 860
  4. J. Kalfus and J. Jancar (2007). Elastic response of nanocomposite poly(vinylacetate)-hydroxyapatite with varying particle shape. Polym. Compos. 28: 365-371
  5. Kalfus J, Jancar J (2007), Viscoelastic response of nanocomposite poly(vynil acetate) hydroxyapatite with varying particle shape- Dynamic strain softening and modulus recovery, Polym. Compos. 28: 743-747
  6. J. Kalfus and J. Jancar (2007), Relaxation processes in PVAc-HA nanocomposites. Polym. Sci.: Part B: Polym. Phys. 45, 1380 (2007)
  7. Kalfus J, Jancar J (2007), Immobilization of polyvinylacetate macromolecules on hydroxyapatite nanoparticles, Polymer 48: 3935-3938
  8. Kalfus J, Jancar J, Kucera J (2008), Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins, Polym. Eng. Sci. 38: 000-000, accepted