M E T H O D S - PowerPoint PPT Presentation

Loading...

PPT – M E T H O D S PowerPoint presentation | free to view - id: 1c969d-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

M E T H O D S

Description:

Among the composite hydrogels, those bearing ionic groups occupy a special place, ... from polyacrylonitrile by the aminolysis-hydrolysis reaction, was used as ... – PowerPoint PPT presentation

Number of Views:53
Avg rating:3.0/5.0
Slides: 2
Provided by: marinel8
Category:
Tags: aminolysis

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: M E T H O D S


1
COVALENT CROSSLINKED COMPOSITE POLYELECTROLYTE
HYDROGEL
ECATERINA STELA DRAGAN, MARIA MARINELA PERJU
Petru Poni Institute of Macromolecular
Chemistry, Iasi, Romania, email sdragan_at_icmpp.ro
M O T I V A T I O N A N D O B J E C T I V E S
  • Among the composite hydrogels, those bearing
    ionic groups occupy a special place, numerous
    contributions being focused on the preparation
    and characterization of such materials, the
    presence of ionic or ionizable centers increasing
    the number of external stimuli, which could
    support their use as smart materials 1-6
  • Preparation of ionic hydrogels by covalent
    cross-linking of two polycations, one natural and
    another one synthetic, both bearing primary amine
    groups able to react with glutaraldehyde (GA) as
    cross-linking agent, was now investigated as a
    novel route to prepare composite hydrogels
  • Chitosan, with a deacetilation degree of 85 has
    been used as a natural weak polycation, and
    polyN-(?-aminoethylene)acrylamide (PAEA),
    derived from polyacrylonitrile by the
    aminolysis-hydrolysis reaction, was used as a
    synthetic weak polycation
  • The main parametres varied to design the
    hydrogel properties were the molar ratio between
    polycations, the ratio between the primary amine
    groups and cross-linking agent, and the total
    concentration of polycations
  • The swelling degree was evaluated as a function
    of the synthesis parameters.

M A T E R I A L S
M E T H O D S
  • Molar mass of chitosan was determined using the
    viscometric method. The intrinsic viscosity of
    chitosan solution in 0.3 M CH3COOH 0.2 M
    CH3COONa (11, V/V) was measured with an
    Ubbelohde viscometer at 25 oC. The viscosity
    average molecular weight of the starting chitosan
    was calculated using the equation ? 1.38 x
    10-4 MV0.85 7
  • FT-IR spectra of the initial polycations and of
    their hydrogels were obtained using a Bruker
    Vertex 70 FT-IR spectrometer. Trasmission spectra
    were recorded in KBr pellets
  • Swelling degree (SD) of hydrogels was calculated
    as follows
  • SD (Ws - Wd)/Wd, where Ws si Wd are the
    weights of the swollen and dry samples,
    respectively.

PolyN-(?-aminoethylene) acrylamide (PAEA)
Chitosan
R E S U L T S
  • Influence of cross-linker concentration on the
    properties of composite hydrogels

GA/NH2, 0.07541 HG 3
GA/NH2, 0.06051 HG 2
GA/NH2, 0.03771 HG 1
FIGURE 2 Swelling kinetics of the composite
hydrogels at 23 oC total concentration of
polycations 3.5 wt. molar ratio PAEACHI
0.7860214.
PAEA
FIGURE 3 Swelling degree as a function of the
molar ratio GA/NH2 at 23 oC total concentration
of polycations 3.5 wt. molar ratio PAEACHI
0.7860.214 the inset, swelling degree as a
function of pH.
  • Swelling degree in water of the composite
    hydrogels as a function of the total
    concentration of polycations and the molar ratio
    PAEA CHI

CHI 1
FIGURE 1 FT-IR spectra of the initial
polycations and of their hydrogels.

R E F E R E N C E S
C O N C L U S I O N S
1. T. Wang, M. Turhan, S. Gunasekaran, Polym.
Int. 2004, 53, 911-918. 2. K.- F. Lin, C.- Y.
Hsu, T.- S. Huang, W.-Y Chiu, Y.- H. Lee, T.- H.
Young J. Appl. Polym. Sci., 2005, 98, 2042 -
2047. 3. J. Berger, M. Reist, J. M. Mayer, O.
Felt, N. A. Peppas, R. Gurny Eur. J. Pharm.
Biopharm., 2004, 57,19 - 34. 4. H.- S. Tsai, Y.-
Z. Wang Polym. Bull., 2008, 60, 103 - 113. 5. K.
De. Yao, T. Peng, H. B. Feng, Y, Y. He J. Polym.
Sci Part A Polym. Chem., 1994, 32, 1213 -
1223. 6. M. Y. Abdelaal, E. A. Abdel- Razik, E.
M. Abdel-Bary, I. M. El- Sherbiny J. Appl. Polym.
Sci., 2007, 103, 2864 -2874. 7. A. I. Gamzazade,
V. M. Shimac, A. M. Skljar, E. V. Stykova, S. A.
Pavlova, S. V. Rogozin Acta Polymerica, 1985, 36,
420 - 424.
  • The swelling degree in water decreased as the
    content of the cross-linking agent increased, as
    expected
  • The increase of the synthetic polycation
    content (PAEA) in the initial polycation mixture
    led to the increase of the swelling degree, PAEA
    being hydrophylic in the whole range of pH
  • A lower total concentration of polycations led
    to a higher swelling degree in water at pH
    6.5-7, the swelling at pH 2 being almost constant.
About PowerShow.com