Dynamics of six generations of PAMAM dendrimers as studied by dielectric relaxation spectroscopy

Jovan Mijovic, Sanja Ristić, Jose Kenny

Research output: Contribution to journalArticle

Abstract

Broadband dielectric relaxation spectroscopy (DRS) was employed to study molecular dynamics of the first six generations of poly(amidoamine) (PAMAM) dendrimers with ethylenediamine core and amino surface groups. DRS was performed over a wide range of frequency and temperature. Dendrimers show distinctly different relaxation behavior below and above the temperature of -30°C, which roughly corresponds to their calorimetric T g. Three relaxation processes are observed below -30°C, and an explanation of their molecular origin is provided. The interplay between molecular architecture and hydrogen bonding was found to have an effect on dielectric relaxation that is not found for dynamic mechanical relaxation. All those processes are characterized by Arrhenius-like temperature dependence. Above -30°C, the spectra are dominated by conductivity and are analyzed using the dielectric modulus and conductivity formalisms. The average relaxation time for the segmental process was calculated from the dielectric loss modulus spectra and found to be of the Vogel -Fulcher-Tammann (VFT) type. An additional process, termed "conductivity relaxation", was observed in the modulus spectra under certain conditions, and an explanation of its molecular origin is offered.

Original languageEnglish (US)
Pages (from-to)5212-5221
Number of pages10
JournalMacromolecules
Volume40
Issue number14
DOIs
StatePublished - Jul 10 2007

Fingerprint

Dielectric relaxation
Dendrimers
ethylenediamine
Spectroscopy
Anelastic relaxation
Relaxation processes
Dielectric losses
Relaxation time
Temperature
Molecular dynamics
Hydrogen bonds
PAMAM Starburst

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Dynamics of six generations of PAMAM dendrimers as studied by dielectric relaxation spectroscopy. / Mijovic, Jovan; Ristić, Sanja; Kenny, Jose.

In: Macromolecules, Vol. 40, No. 14, 10.07.2007, p. 5212-5221.

Research output: Contribution to journalArticle

@article{bf3844f1922b4f1090bfe162507a33f6,
title = "Dynamics of six generations of PAMAM dendrimers as studied by dielectric relaxation spectroscopy",
abstract = "Broadband dielectric relaxation spectroscopy (DRS) was employed to study molecular dynamics of the first six generations of poly(amidoamine) (PAMAM) dendrimers with ethylenediamine core and amino surface groups. DRS was performed over a wide range of frequency and temperature. Dendrimers show distinctly different relaxation behavior below and above the temperature of -30°C, which roughly corresponds to their calorimetric T g. Three relaxation processes are observed below -30°C, and an explanation of their molecular origin is provided. The interplay between molecular architecture and hydrogen bonding was found to have an effect on dielectric relaxation that is not found for dynamic mechanical relaxation. All those processes are characterized by Arrhenius-like temperature dependence. Above -30°C, the spectra are dominated by conductivity and are analyzed using the dielectric modulus and conductivity formalisms. The average relaxation time for the segmental process was calculated from the dielectric loss modulus spectra and found to be of the Vogel -Fulcher-Tammann (VFT) type. An additional process, termed {"}conductivity relaxation{"}, was observed in the modulus spectra under certain conditions, and an explanation of its molecular origin is offered.",
author = "Jovan Mijovic and Sanja Ristić and Jose Kenny",
year = "2007",
month = "7",
day = "10",
doi = "10.1021/ma070624q",
language = "English (US)",
volume = "40",
pages = "5212--5221",
journal = "Macromolecules",
issn = "0024-9297",
publisher = "American Chemical Society",
number = "14",

}

TY - JOUR

T1 - Dynamics of six generations of PAMAM dendrimers as studied by dielectric relaxation spectroscopy

AU - Mijovic, Jovan

AU - Ristić, Sanja

AU - Kenny, Jose

PY - 2007/7/10

Y1 - 2007/7/10

N2 - Broadband dielectric relaxation spectroscopy (DRS) was employed to study molecular dynamics of the first six generations of poly(amidoamine) (PAMAM) dendrimers with ethylenediamine core and amino surface groups. DRS was performed over a wide range of frequency and temperature. Dendrimers show distinctly different relaxation behavior below and above the temperature of -30°C, which roughly corresponds to their calorimetric T g. Three relaxation processes are observed below -30°C, and an explanation of their molecular origin is provided. The interplay between molecular architecture and hydrogen bonding was found to have an effect on dielectric relaxation that is not found for dynamic mechanical relaxation. All those processes are characterized by Arrhenius-like temperature dependence. Above -30°C, the spectra are dominated by conductivity and are analyzed using the dielectric modulus and conductivity formalisms. The average relaxation time for the segmental process was calculated from the dielectric loss modulus spectra and found to be of the Vogel -Fulcher-Tammann (VFT) type. An additional process, termed "conductivity relaxation", was observed in the modulus spectra under certain conditions, and an explanation of its molecular origin is offered.

AB - Broadband dielectric relaxation spectroscopy (DRS) was employed to study molecular dynamics of the first six generations of poly(amidoamine) (PAMAM) dendrimers with ethylenediamine core and amino surface groups. DRS was performed over a wide range of frequency and temperature. Dendrimers show distinctly different relaxation behavior below and above the temperature of -30°C, which roughly corresponds to their calorimetric T g. Three relaxation processes are observed below -30°C, and an explanation of their molecular origin is provided. The interplay between molecular architecture and hydrogen bonding was found to have an effect on dielectric relaxation that is not found for dynamic mechanical relaxation. All those processes are characterized by Arrhenius-like temperature dependence. Above -30°C, the spectra are dominated by conductivity and are analyzed using the dielectric modulus and conductivity formalisms. The average relaxation time for the segmental process was calculated from the dielectric loss modulus spectra and found to be of the Vogel -Fulcher-Tammann (VFT) type. An additional process, termed "conductivity relaxation", was observed in the modulus spectra under certain conditions, and an explanation of its molecular origin is offered.

UR - http://www.scopus.com/inward/record.url?scp=34547401124&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547401124&partnerID=8YFLogxK

U2 - 10.1021/ma070624q

DO - 10.1021/ma070624q

M3 - Article

VL - 40

SP - 5212

EP - 5221

JO - Macromolecules

JF - Macromolecules

SN - 0024-9297

IS - 14

ER -