We probe, using the surface forces apparatus, the thermal response of poly(N-isopropylacrylamide) (PNIPAM) brushes of various grafting densities, grown from plasma-activated mica by means of surface-initiated polymerization. We thus show that dense thermoresponsive brushes collapse gradually as temperature is increased and that grafting density greatly affects their ability to swell: the swelling ratio of the brushes, which characterizes the thickness variation between the swollen and the collapsed state, is found to decrease from approximately 7 to approximately 3 as the number of grafted chains per unit area increases. Such a result, obtained with an unprecedented resolution in grafting density, provides qualitative support to calculations by Mendez et al. [Macromolecules 2005, 38, 174]. We further show that, in contrast to swelling, adhesion between two PNIPAM brushes appears to be rather insensitive to their molecular structure.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/la9035387 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Gold Nanorod-Coated Hydrogel Brush Valves in Macroporous Silicon Membranes for NIR-Driven Localized Chemical Modulation.
Gels
January 2025
Department of Electrical Engineering, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
A two-dimensional array of microfluidic ports with remote-controlled valve actuation is of great interest for applications involving localized chemical stimulation. Herein, a macroporous silicon-based platform where each pore contains an independently controllable valve made from poly(N-isopropylacrylamide) (PNIPAM) brushes is proposed. These valves are coated with silica-encapsulated gold nanorods (GNRs) for NIR-actuated switching capability.
View Article and Find Full Text PDFTemperature-modulated interactions between thermoresponsive strong cationic copolymer-brush-grafted silica beads and biomolecules.
Heliyon
August 2024
Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato, Tokyo, 105-8512, Japan.
Thermoresponsive polymer brushes have attracted considerable research attention owing to their unique properties. Herein, we developed silica beads grafted with poly(-isopropylacrylamide (NIPAAm)--3-acrylamidopropyl trimethylammonium chloride (APTAC)---butyl acrylamide (tBAAm) and P(NIPAAm--APTAC---butyl methacrylate(nBMA)) brushes. The carbon, hydrogen, and nitrogen elemental analysis of the copolymer-grated silica beads revealed the presence of a large amount of the grafted copolymer on the silica beads.
View Article and Find Full Text PDFWater Confinement on Polymer Coatings Dictates Proton-Electron Transfer on Metal-Catalyzed Hydrogenation of Nitrite.
JACS Au
July 2024
Catalytic Processes and Materials Group, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede 7500 AE, The Netherlands.
Enzymes can precisely control the speed and selectivity of chemical reactions by modifying locally the solvent-reactant interactions. To extrapolate these attributes to heterogeneous catalysts, we have employed thermoresponsive poly -isopropylacrylamide (-NIPAM) brushes bonded to silica spheres containing palladium. These polymers can form hydrogen bonds with water molecules at low temperatures (<32 °C) allowing the polymer to stay swollen.
View Article and Find Full Text PDFPreparation and Performance Study of HTPB--(PNIPAM/PEG) Thermoresponsive Polymer Brush.
Polymers (Basel)
April 2024
The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an 710072, China.
In recent years, a great deal of work has been devoted to the development of thermoresponsive polymers that can be made into new types of smart materials. In this paper, a branched polymer, HTPB--(PNIPAM/PEG), with polyolefin chain segments as the backbone and having polyethylene glycol (PEG) and poly(N-isopropylacrylamide) (PNIPAM) as side chains was synthesized by ATRP and click reactions using N-HTPB-Br as the macroinitiator. This initiator was designed and synthesized using hydroxyl-terminated polybutadiene (HTPB) as the substrate.
View Article and Find Full Text PDFTemperature-modulated separation of vascular cells using thermoresponsive-anionic block copolymer-modified glass.
Regen Ther
December 2024
Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo, 105-8512, Japan.
Introduction: Vascular tissue engineering is a key technology in the field of regenerative medicine. In tissue engineering, the separation of vascular cells without cell modification is required, as cell modifications affect the intrinsic properties of the cells. In this study, we have developed an effective method for separating vascular cells without cell modification, using a thermoresponsive anionic block copolymer.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!