Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Apr 5;27(7):4142-8.
doi: 10.1021/la200114s. Epub 2011 Mar 14.

Control of poly(N-isopropylacrylamide) microgel network structure by precipitation polymerization near the lower critical solution temperature

Xiaobo Hu  1 , Zhen Tong, L Andrew Lyon
Affiliations

Control of poly(N-isopropylacrylamide) microgel network structure by precipitation polymerization near the lower critical solution temperature

Xiaobo Hu et al. Langmuir. .

Abstract

Poly(N-isopropylacrylamide) (pNIPAm) microgels were synthesized by precipitation polymerization at temperatures ranging from 37 to 45 °C using redox initiator system ammonium persulfate (APS)/N,N,N',N'-tetramethylethylenediamine (TEMED) or photoinitiator 2,2'-azobis(amidinopropane) dihydrochloride (V50). Photon correlation spectroscopy (PCS) and atomic force microscopy (AFM) studies revealed that spherical microgels with narrow size dispersities can be obtained with these methods and that the resultant microgels have volume phase transition behaviors expected from their compositions. Additionally, the low-temperature redox initiator strategy produces microgels devoid of self-cross-linking, thereby permitting the synthesis of completely degradable microgels when using N,N'-(1,2-dihydroxyethylene)bisacrylamide (DHEA) as a cleavable cross-linker. We also demonstrate the potential utility of the approach in bioconjugate syntheses; in this case, avidin immobilization is demonstrated by one-pot copolymerization at low temperature.

PubMed Disclaimer

Figures

Figure 1
Figure 1
AFM height images of (a) 45A1, (b) 45AT1, (c) 37AT1 and (d) 70A1 microgels on glass substrates. The z-scale is the same for all images and is shown next to panel (d).
Figure 2
Figure 2
AFM height images of (a) 45V, (b) 37VL and (c) 45VL microgels on glass substrates. The z-scale is the same for all images and is shown next to panel (c).
Figure 3
Figure 3
Variation in radius (a) and swelling ratio (b) as a function of temperature for the pNIPAm microgels described in the text.
Figure 4
Figure 4
Schematic depiction of the formation process of self-cross-linked network (a), step 1: chain transfer to polymers; step 2: monomer addition, coupling termination and network formation. (b) Chain transfer to TEMED, which will limit chain branching.
Figure 5
Figure 5
AFM height images of substrate-supported 70A1-C (a, b) and 45AT1-C (c, d) microgels before (a, c) and after (b, d) periodate-induced degradation. The z-scale is the same for all images and is shown next to panel (d).
Figure 6
Figure 6
Fluorescence spectra of fluorescein-biotin treated microgels synthesized by using NAS-modified (solid line) or native (dotted line) avidin.
See this image and copyright information in PMC

References

    1. Fernandez-Barbero A, Suarez IJ, Sierra-Martin B, Fernandez-Nieves A, de las Nieves FJ, Marquez M, Rubio-Retama J, Lopez-Cabarcos E. Adv. Colloid Interface Sci. 2009;147-48:88. - PubMed
    1. Motornov M, Roiter Y, Tokarev I, Minko S. Prog. Polym. Sci. 2010;35:174.
    1. Li YY, Dong HQ, Wang K, Shi DL, Zhang XZ, Zhuo RX. Sci. China Chem. 2010;53:447.
    1. Hendrickson GR, Smith MH, South AB, Lyon LA. Adv. Funct. Mater. 2010;20:1697.
    1. Nayak S, Lyon LA. Angew. Chem. Int. Ed. 2005;44:7686. - PubMed

Publication types