Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene

Jun Shan, Markus Nuopponen, Hua Jiang, Tapani Viitala, Esko I. Kauppinen, Kyösti Kontturi, Heikki Tenhu (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

141 Citations (Scopus)

Abstract

Two types of amphiphilic gold nanoparticles (AuNP-1 and -2) grafted with a mixture of poly(N-isopropylacrylamide) (PNIPAM) and polystyrene (PS) chains in two different compositions have been successfully prepared with the “grafting-to” method in a homogeneous THF phase. These AuNPs were thoroughly characterized by FTIR, 1H NMR, UV−vis, high-resolution transmission electron microscopy, thermogravimetric analysis, and dynamic light scattering to determine the total number of polymer chains bound to the gold nanoparticles, the ratio between PNIPAM and PS chains, and the size of the gold core. Langmuir monolayer experiments at the air−water interface of the two types of AuNPs revealed different compression isotherms of the surface pressure vs particle area (π−A curve) conducted at 20 °C. These amphiphilic gold nanoparticles can be regarded as analogues of amphiphilic diblock copolymers at the air−water interface. The compression isotherm of AuNP-2 with a PNIPAM:PS ratio of 2:1 showed several characteristic regions that can be attributed to the polymer conformational transitions from the pancake, the pancake to brush transition, to the brush. However, the monolayer of AuNP-1, with a ratio of 5:1 of PNIPAM:PS, never reaches a brush stage but showed an extension of the pseudoplateau region upon compression. These differences may be due to the more hydrophilic nature and the more stretched PNIPAM chains. Furthermore, the sessile drop contact angle measurements, conducted at room temperature on both upper and lower surfaces of the AuNP-2 monolayer transferred at 35 mN/m onto either hydrophilic or hydrophobic substrates, are slightly different, 82 ± 2° and 77 ± 2°, respectively. After comparing with the literature data of the contact angles of water on either the pure PS film or the PNIPAM brush, we concluded that the chemically different PNIPAM and PS chains grafted on the surface of the gold core tend to be phase-separated.
Original languageEnglish
Pages (from-to)2918 - 2926
Number of pages9
JournalMacromolecules
Volume38
Issue number7
DOIs
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed

Fingerprint

Polystyrenes
Gold
Brushes
Nanoparticles
Monolayers
Contact angle
Isotherms
Polymers
Dynamic light scattering
Angle measurement
High resolution transmission electron microscopy
Block copolymers
Thermogravimetric analysis
poly-N-isopropylacrylamide
Nuclear magnetic resonance
Substrates
Chemical analysis
Water
Experiments

Keywords

  • gold
  • gold nanoparticles
  • nanoparticles
  • thiolated polymers
  • polymer ligands
  • stabilization
  • grafting

Cite this

Shan, J., Nuopponen, M., Jiang, H., Viitala, T., Kauppinen, E. I., Kontturi, K., & Tenhu, H. (2005). Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene. Macromolecules, 38(7), 2918 - 2926. https://doi.org/10.1021/ma049269j
Shan, Jun ; Nuopponen, Markus ; Jiang, Hua ; Viitala, Tapani ; Kauppinen, Esko I. ; Kontturi, Kyösti ; Tenhu, Heikki. / Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene. In: Macromolecules. 2005 ; Vol. 38, No. 7. pp. 2918 - 2926.
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abstract = "Two types of amphiphilic gold nanoparticles (AuNP-1 and -2) grafted with a mixture of poly(N-isopropylacrylamide) (PNIPAM) and polystyrene (PS) chains in two different compositions have been successfully prepared with the “grafting-to” method in a homogeneous THF phase. These AuNPs were thoroughly characterized by FTIR, 1H NMR, UV−vis, high-resolution transmission electron microscopy, thermogravimetric analysis, and dynamic light scattering to determine the total number of polymer chains bound to the gold nanoparticles, the ratio between PNIPAM and PS chains, and the size of the gold core. Langmuir monolayer experiments at the air−water interface of the two types of AuNPs revealed different compression isotherms of the surface pressure vs particle area (π−A curve) conducted at 20 °C. These amphiphilic gold nanoparticles can be regarded as analogues of amphiphilic diblock copolymers at the air−water interface. The compression isotherm of AuNP-2 with a PNIPAM:PS ratio of 2:1 showed several characteristic regions that can be attributed to the polymer conformational transitions from the pancake, the pancake to brush transition, to the brush. However, the monolayer of AuNP-1, with a ratio of 5:1 of PNIPAM:PS, never reaches a brush stage but showed an extension of the pseudoplateau region upon compression. These differences may be due to the more hydrophilic nature and the more stretched PNIPAM chains. Furthermore, the sessile drop contact angle measurements, conducted at room temperature on both upper and lower surfaces of the AuNP-2 monolayer transferred at 35 mN/m onto either hydrophilic or hydrophobic substrates, are slightly different, 82 ± 2° and 77 ± 2°, respectively. After comparing with the literature data of the contact angles of water on either the pure PS film or the PNIPAM brush, we concluded that the chemically different PNIPAM and PS chains grafted on the surface of the gold core tend to be phase-separated.",
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Shan, J, Nuopponen, M, Jiang, H, Viitala, T, Kauppinen, EI, Kontturi, K & Tenhu, H 2005, 'Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene', Macromolecules, vol. 38, no. 7, pp. 2918 - 2926. https://doi.org/10.1021/ma049269j

Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene. / Shan, Jun; Nuopponen, Markus; Jiang, Hua; Viitala, Tapani; Kauppinen, Esko I.; Kontturi, Kyösti; Tenhu, Heikki (Corresponding Author).

In: Macromolecules, Vol. 38, No. 7, 2005, p. 2918 - 2926.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene

AU - Shan, Jun

AU - Nuopponen, Markus

AU - Jiang, Hua

AU - Viitala, Tapani

AU - Kauppinen, Esko I.

AU - Kontturi, Kyösti

AU - Tenhu, Heikki

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N2 - Two types of amphiphilic gold nanoparticles (AuNP-1 and -2) grafted with a mixture of poly(N-isopropylacrylamide) (PNIPAM) and polystyrene (PS) chains in two different compositions have been successfully prepared with the “grafting-to” method in a homogeneous THF phase. These AuNPs were thoroughly characterized by FTIR, 1H NMR, UV−vis, high-resolution transmission electron microscopy, thermogravimetric analysis, and dynamic light scattering to determine the total number of polymer chains bound to the gold nanoparticles, the ratio between PNIPAM and PS chains, and the size of the gold core. Langmuir monolayer experiments at the air−water interface of the two types of AuNPs revealed different compression isotherms of the surface pressure vs particle area (π−A curve) conducted at 20 °C. These amphiphilic gold nanoparticles can be regarded as analogues of amphiphilic diblock copolymers at the air−water interface. The compression isotherm of AuNP-2 with a PNIPAM:PS ratio of 2:1 showed several characteristic regions that can be attributed to the polymer conformational transitions from the pancake, the pancake to brush transition, to the brush. However, the monolayer of AuNP-1, with a ratio of 5:1 of PNIPAM:PS, never reaches a brush stage but showed an extension of the pseudoplateau region upon compression. These differences may be due to the more hydrophilic nature and the more stretched PNIPAM chains. Furthermore, the sessile drop contact angle measurements, conducted at room temperature on both upper and lower surfaces of the AuNP-2 monolayer transferred at 35 mN/m onto either hydrophilic or hydrophobic substrates, are slightly different, 82 ± 2° and 77 ± 2°, respectively. After comparing with the literature data of the contact angles of water on either the pure PS film or the PNIPAM brush, we concluded that the chemically different PNIPAM and PS chains grafted on the surface of the gold core tend to be phase-separated.

AB - Two types of amphiphilic gold nanoparticles (AuNP-1 and -2) grafted with a mixture of poly(N-isopropylacrylamide) (PNIPAM) and polystyrene (PS) chains in two different compositions have been successfully prepared with the “grafting-to” method in a homogeneous THF phase. These AuNPs were thoroughly characterized by FTIR, 1H NMR, UV−vis, high-resolution transmission electron microscopy, thermogravimetric analysis, and dynamic light scattering to determine the total number of polymer chains bound to the gold nanoparticles, the ratio between PNIPAM and PS chains, and the size of the gold core. Langmuir monolayer experiments at the air−water interface of the two types of AuNPs revealed different compression isotherms of the surface pressure vs particle area (π−A curve) conducted at 20 °C. These amphiphilic gold nanoparticles can be regarded as analogues of amphiphilic diblock copolymers at the air−water interface. The compression isotherm of AuNP-2 with a PNIPAM:PS ratio of 2:1 showed several characteristic regions that can be attributed to the polymer conformational transitions from the pancake, the pancake to brush transition, to the brush. However, the monolayer of AuNP-1, with a ratio of 5:1 of PNIPAM:PS, never reaches a brush stage but showed an extension of the pseudoplateau region upon compression. These differences may be due to the more hydrophilic nature and the more stretched PNIPAM chains. Furthermore, the sessile drop contact angle measurements, conducted at room temperature on both upper and lower surfaces of the AuNP-2 monolayer transferred at 35 mN/m onto either hydrophilic or hydrophobic substrates, are slightly different, 82 ± 2° and 77 ± 2°, respectively. After comparing with the literature data of the contact angles of water on either the pure PS film or the PNIPAM brush, we concluded that the chemically different PNIPAM and PS chains grafted on the surface of the gold core tend to be phase-separated.

KW - gold

KW - gold nanoparticles

KW - nanoparticles

KW - thiolated polymers

KW - polymer ligands

KW - stabilization

KW - grafting

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Shan J, Nuopponen M, Jiang H, Viitala T, Kauppinen EI, Kontturi K et al. Amphiphilic gold nanoparticles grafted with poly(N-isopropylacrylamide) and polystyrene. Macromolecules. 2005;38(7):2918 - 2926. https://doi.org/10.1021/ma049269j