Investigation of the structure and swelling of poly(N-isopropyl-acrylamide-acrylamide) and poly(N-isopropyl-acrylamide-acrylic acid) based copolymer and composite hydrogels

László Janovák, János Varga, L. Kemény, I. Dékány

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We synthesized, thermo- and pH-sensitive gels and tested them as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. In the course of the polymerization reaction, we produced copolymers with variable compositions, starting from different acrylic compounds [N-isopropyl-acrylamide (NIPAAm), acrylamide (AAm), and acrylic acid (AAc)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na-montmorillonite and Na-montmorillonites organophilized with alkylammonium ions (Cn-m.), n = 4, 12, 18]. With this method we synthesized composite hydrogels. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1-5 wt.%) resulted in more extensive swelling and stronger gel structure. During the experiments, the monomer composition (0/100-100/0 mol% NIPAAm/AAm or AAc) and the cross-link density (50-1500 mol%) of the gels (M/C ratio) and, in the case of composites, the quality and quantity of fillers are varied. The filler content of composites varies between 1 and 25 wt.%. The extent of swelling and the viscoelastic properties can be manipulated through the ratios of these parameters. In the case of certain copolymer and composite gels, values of desorption enthalpy (ΔHm) corresponding to the actual water contents were also determined by thermoanalytical measurements (differential scanning calorimetry, DSC). Swelling values determined by gravimetry and enthalpies calculated from DSC measurements were found to be in good correlation. Even in the case of the relatively hydrophobic poly(NIPAAm)-based gels, an enthalpy value of 98.41 kJ/mol was obtained, which is twice the value measured in pure water (41.74 kJ/ mol). Evaluation and comparison of the rheological and DSC results also allowed conclusions to be drawn concerning the types of interaction operating among the three components of the system, i.e., the polymer skeleton and the filler and water molecules.

Original languageEnglish
Pages (from-to)1575-1585
Number of pages11
JournalColloid & Polymer Science
Volume286
Issue number14-15
DOIs
Publication statusPublished - 2008

Fingerprint

Hydrogels
acrylic acid
fillers
swelling
Acrylics
Swelling
Fillers
copolymers
Gels
Copolymers
Acrylamide
gels
composite materials
Acids
Composite materials
Differential scanning calorimetry
Enthalpy
Skin
heat measurement
enthalpy

Keywords

  • Clay-mineral composites
  • Copolymers
  • DSC
  • Mechanical properties
  • Skin expander
  • Swelling hydrogel

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry
  • Colloid and Surface Chemistry

Cite this

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title = "Investigation of the structure and swelling of poly(N-isopropyl-acrylamide-acrylamide) and poly(N-isopropyl-acrylamide-acrylic acid) based copolymer and composite hydrogels",
abstract = "We synthesized, thermo- and pH-sensitive gels and tested them as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. In the course of the polymerization reaction, we produced copolymers with variable compositions, starting from different acrylic compounds [N-isopropyl-acrylamide (NIPAAm), acrylamide (AAm), and acrylic acid (AAc)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na-montmorillonite and Na-montmorillonites organophilized with alkylammonium ions (Cn-m.), n = 4, 12, 18]. With this method we synthesized composite hydrogels. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1-5 wt.{\%}) resulted in more extensive swelling and stronger gel structure. During the experiments, the monomer composition (0/100-100/0 mol{\%} NIPAAm/AAm or AAc) and the cross-link density (50-1500 mol{\%}) of the gels (M/C ratio) and, in the case of composites, the quality and quantity of fillers are varied. The filler content of composites varies between 1 and 25 wt.{\%}. The extent of swelling and the viscoelastic properties can be manipulated through the ratios of these parameters. In the case of certain copolymer and composite gels, values of desorption enthalpy (ΔHm) corresponding to the actual water contents were also determined by thermoanalytical measurements (differential scanning calorimetry, DSC). Swelling values determined by gravimetry and enthalpies calculated from DSC measurements were found to be in good correlation. Even in the case of the relatively hydrophobic poly(NIPAAm)-based gels, an enthalpy value of 98.41 kJ/mol was obtained, which is twice the value measured in pure water (41.74 kJ/ mol). Evaluation and comparison of the rheological and DSC results also allowed conclusions to be drawn concerning the types of interaction operating among the three components of the system, i.e., the polymer skeleton and the filler and water molecules.",
keywords = "Clay-mineral composites, Copolymers, DSC, Mechanical properties, Skin expander, Swelling hydrogel",
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TY - JOUR

T1 - Investigation of the structure and swelling of poly(N-isopropyl-acrylamide-acrylamide) and poly(N-isopropyl-acrylamide-acrylic acid) based copolymer and composite hydrogels

AU - Janovák, László

AU - Varga, János

AU - Kemény, L.

AU - Dékány, I.

PY - 2008

Y1 - 2008

N2 - We synthesized, thermo- and pH-sensitive gels and tested them as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. In the course of the polymerization reaction, we produced copolymers with variable compositions, starting from different acrylic compounds [N-isopropyl-acrylamide (NIPAAm), acrylamide (AAm), and acrylic acid (AAc)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na-montmorillonite and Na-montmorillonites organophilized with alkylammonium ions (Cn-m.), n = 4, 12, 18]. With this method we synthesized composite hydrogels. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1-5 wt.%) resulted in more extensive swelling and stronger gel structure. During the experiments, the monomer composition (0/100-100/0 mol% NIPAAm/AAm or AAc) and the cross-link density (50-1500 mol%) of the gels (M/C ratio) and, in the case of composites, the quality and quantity of fillers are varied. The filler content of composites varies between 1 and 25 wt.%. The extent of swelling and the viscoelastic properties can be manipulated through the ratios of these parameters. In the case of certain copolymer and composite gels, values of desorption enthalpy (ΔHm) corresponding to the actual water contents were also determined by thermoanalytical measurements (differential scanning calorimetry, DSC). Swelling values determined by gravimetry and enthalpies calculated from DSC measurements were found to be in good correlation. Even in the case of the relatively hydrophobic poly(NIPAAm)-based gels, an enthalpy value of 98.41 kJ/mol was obtained, which is twice the value measured in pure water (41.74 kJ/ mol). Evaluation and comparison of the rheological and DSC results also allowed conclusions to be drawn concerning the types of interaction operating among the three components of the system, i.e., the polymer skeleton and the filler and water molecules.

AB - We synthesized, thermo- and pH-sensitive gels and tested them as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. In the course of the polymerization reaction, we produced copolymers with variable compositions, starting from different acrylic compounds [N-isopropyl-acrylamide (NIPAAm), acrylamide (AAm), and acrylic acid (AAc)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na-montmorillonite and Na-montmorillonites organophilized with alkylammonium ions (Cn-m.), n = 4, 12, 18]. With this method we synthesized composite hydrogels. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1-5 wt.%) resulted in more extensive swelling and stronger gel structure. During the experiments, the monomer composition (0/100-100/0 mol% NIPAAm/AAm or AAc) and the cross-link density (50-1500 mol%) of the gels (M/C ratio) and, in the case of composites, the quality and quantity of fillers are varied. The filler content of composites varies between 1 and 25 wt.%. The extent of swelling and the viscoelastic properties can be manipulated through the ratios of these parameters. In the case of certain copolymer and composite gels, values of desorption enthalpy (ΔHm) corresponding to the actual water contents were also determined by thermoanalytical measurements (differential scanning calorimetry, DSC). Swelling values determined by gravimetry and enthalpies calculated from DSC measurements were found to be in good correlation. Even in the case of the relatively hydrophobic poly(NIPAAm)-based gels, an enthalpy value of 98.41 kJ/mol was obtained, which is twice the value measured in pure water (41.74 kJ/ mol). Evaluation and comparison of the rheological and DSC results also allowed conclusions to be drawn concerning the types of interaction operating among the three components of the system, i.e., the polymer skeleton and the filler and water molecules.

KW - Clay-mineral composites

KW - Copolymers

KW - DSC

KW - Mechanical properties

KW - Skin expander

KW - Swelling hydrogel

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U2 - 10.1007/s00396-008-1933-8

DO - 10.1007/s00396-008-1933-8

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JO - Kolloid Zeitschrift

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