Abstract
It is now well-accepted that controlling the spatial dispersion of nanoparticles (NPs), which can be achieved by grafting them with polymers of different chain lengths and grafting densities, is central to optimizing the thermomechanical properties of the resulting polymer nanocomposites. In general, there are two methods for creating such polymer-grafted NPs: "grafting to" and "grafting from". The conventional wisdom is that the "grafting from" mechanism, where monomer-sized initiator/functional groups are attached to the surface followed by growing the chains, allows for higher polymer grafting densities and hence a more uniform polymer coverage of the NP surface. Here, we perform calculations and instead show that the "grafting to" strategy surprisingly leads to a more uniform polymer coverage of the NP surface at a given grafting density since the brush is formed while respecting the excluded volume constraints of the previously grafted chains. This conclusion is especially clear in the limit of low-to-moderate grafting density. Thus, at a given grafting density, the "grafting to" mechanism leads to an enhanced miscibility of the NPs in the matrix (which has the same chemistry as the grafts) and lower propensity to create self-assembled structures. Another important factor is that the dispersity in the number of grafted chains on the NPs is also smaller in the case of "grafting to" systems, thus leading to better defined materials. These two conclusions imply that the "grafting to" mechanism may provide better control over the NP dispersion state and hence the thermomechanical properties of polymer nanocomposites.
| Original language | English |
|---|---|
| Pages (from-to) | 7028-7035 |
| Number of pages | 8 |
| Journal | ACS Nano |
| Volume | 11 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 2017 Jul 25 |
| Externally published | Yes |
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Keywords
- anisotropy
- distribution of grafting density
- excluded volume effect
- grafting process
- polymer grafted nanoparticle
- self-assembly
- surface coverage
ASJC Scopus subject areas
- Materials Science(all)
- Engineering(all)
- Physics and Astronomy(all)
Cite this
Role of Grafting Mechanism on the Polymer Coverage and Self-Assembly of Hairy Nanoparticles. / Asai, Makoto; Zhao, Dan; Kumar, Sanat K.
In: ACS Nano, Vol. 11, No. 7, 25.07.2017, p. 7028-7035.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Role of Grafting Mechanism on the Polymer Coverage and Self-Assembly of Hairy Nanoparticles
AU - Asai, Makoto
AU - Zhao, Dan
AU - Kumar, Sanat K.
PY - 2017/7/25
Y1 - 2017/7/25
N2 - It is now well-accepted that controlling the spatial dispersion of nanoparticles (NPs), which can be achieved by grafting them with polymers of different chain lengths and grafting densities, is central to optimizing the thermomechanical properties of the resulting polymer nanocomposites. In general, there are two methods for creating such polymer-grafted NPs: "grafting to" and "grafting from". The conventional wisdom is that the "grafting from" mechanism, where monomer-sized initiator/functional groups are attached to the surface followed by growing the chains, allows for higher polymer grafting densities and hence a more uniform polymer coverage of the NP surface. Here, we perform calculations and instead show that the "grafting to" strategy surprisingly leads to a more uniform polymer coverage of the NP surface at a given grafting density since the brush is formed while respecting the excluded volume constraints of the previously grafted chains. This conclusion is especially clear in the limit of low-to-moderate grafting density. Thus, at a given grafting density, the "grafting to" mechanism leads to an enhanced miscibility of the NPs in the matrix (which has the same chemistry as the grafts) and lower propensity to create self-assembled structures. Another important factor is that the dispersity in the number of grafted chains on the NPs is also smaller in the case of "grafting to" systems, thus leading to better defined materials. These two conclusions imply that the "grafting to" mechanism may provide better control over the NP dispersion state and hence the thermomechanical properties of polymer nanocomposites.
AB - It is now well-accepted that controlling the spatial dispersion of nanoparticles (NPs), which can be achieved by grafting them with polymers of different chain lengths and grafting densities, is central to optimizing the thermomechanical properties of the resulting polymer nanocomposites. In general, there are two methods for creating such polymer-grafted NPs: "grafting to" and "grafting from". The conventional wisdom is that the "grafting from" mechanism, where monomer-sized initiator/functional groups are attached to the surface followed by growing the chains, allows for higher polymer grafting densities and hence a more uniform polymer coverage of the NP surface. Here, we perform calculations and instead show that the "grafting to" strategy surprisingly leads to a more uniform polymer coverage of the NP surface at a given grafting density since the brush is formed while respecting the excluded volume constraints of the previously grafted chains. This conclusion is especially clear in the limit of low-to-moderate grafting density. Thus, at a given grafting density, the "grafting to" mechanism leads to an enhanced miscibility of the NPs in the matrix (which has the same chemistry as the grafts) and lower propensity to create self-assembled structures. Another important factor is that the dispersity in the number of grafted chains on the NPs is also smaller in the case of "grafting to" systems, thus leading to better defined materials. These two conclusions imply that the "grafting to" mechanism may provide better control over the NP dispersion state and hence the thermomechanical properties of polymer nanocomposites.
KW - anisotropy
KW - distribution of grafting density
KW - excluded volume effect
KW - grafting process
KW - polymer grafted nanoparticle
KW - self-assembly
KW - surface coverage
UR - http://www.scopus.com/inward/record.url?scp=85026312480&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85026312480&partnerID=8YFLogxK
U2 - 10.1021/acsnano.7b02657
DO - 10.1021/acsnano.7b02657
M3 - Article
C2 - 28618225
AN - SCOPUS:85026312480
VL - 11
SP - 7028
EP - 7035
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 7
ER -