Phase Separation Induced Mechanical Transition of Poly(N-isopropylacrylamide)/Water Isochore Gels

Shibayama, Mitsuhiro; Morimoto, Masahiro; Nomura, Shunji

doi:10.1021/ma00096a031

Cited by 207 publications

(200 citation statements)

References 10 publications

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“…This conformational transition accounts for changes in both polymer volume and mechanical properties. 33 The AFM study in our work demonstrates that the ppNIPAM thin film is still able to transition between the collapsed and swollen state as the temperature is changed. However, when comparing the mechanical characteristics of the ppNIPAM thin film produced in our system with those of the pNIPAM gel synthesized by free radical polymerization in the bulk state, some obvious differences are noticed.…”

Section: Mechanical Property By Force Displacement Curvesmentioning

confidence: 57%

Surface Chemical and Mechanical Properties of Plasma-Polymerized N-Isopropylacrylamide

et al. 2005

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Surface immobilized poly(N-isopropyl acrylamide) (pNIPAM) is currently used for a wide variety of biosensor and biomaterial applications. A thorough characterization of the surface properties of pNIPAM thin films will benefit those applications. In this work, we present analysis of a plasma polymerized NIPAM (ppNIPAM) coating by multiple surface analytical techniques, including timeof-flight secondary ion mass spectrometry (ToF-SIMS), contact angle measurement, atomic force microscopy (AFM) and sum frequency generation (SFG) vibrational spectroscopy. ToF-SIMS data show that the plasma-deposited NIPAM polymer on the substrate is crosslinked with a good retention of the monomer integrity. Contact angle results confirm the thermoresponse of the film as observed by a change of surface wettability as a function of temperature. Topographic and force distance curve measurements by AFM further demonstrate that the grafted film shrinks or swells depending on the temperature of the aqueous environment. A clear transition of the elastic modulus is observed at 31-32°C. The change of the surface wettability and mechanical properties vs. temperature are attributed to different conformations taken by the polymer, which is reflected on the outmost surface as distinct side chain groups orienting outwards at different temperatures as measured by SFG. The results suggest that a ppNIPAM thin film on a substrate experiences similar mechanical and chemical changes to pNIPAM bulk polymers in solution. The SFG result provides evidence supporting the current theory of the lower critical solution temperature (LCST) behavior of pNIPAM.

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Section: Mechanical Property By Force Displacement Curvesmentioning

confidence: 57%

Surface Chemical and Mechanical Properties of Plasma-Polymerized N-Isopropylacrylamide

et al. 2005

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“…The curve of the pure cross-linked PDEA (b) shows two endotherms at 36 and 49 °C corresponding to the dissociation of the hydrophobic interaction indicating the existence of two main regions in the PDEA matrix [36] . The associated heat of the first endotherm is higher than the second one.…”

Section: Resultsmentioning

confidence: 99%

Polyurethane/Poly(2-(Diethyl Amino)Ethyl Methacrylate) blend for drug delivery applications

Echeverría¹,

Pardini²,

Debandi

et al. 2015

Polímeros

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SbstractA pH-sensitive blend of polyurethane (PU) and poly(2-(diethyl amino)ethyl methacrylate (PDEA) with good film-forming capacity was prepared from the corresponding aqueous dispersions. The polymer matrix was first characterized by using FTIR, DSC, water vapor transmission and water swelling capacity at different pHs. The drug release profile of films was evaluated using a vertical Franz Cell and theophylline as model drug. The water swelling degree increases from 54 to 180% when the pH of the medium is changed from 6 to 2, demonstrating the pH-responsive behavior of the film. The in-vitro release studies indicate that an anomalous transport mechanism governs the theophylline release.

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“…PNIPA is in the collapsed state in 500 mM phenol solution, i.e., this sample was prepared above LCST conditions. Instead of the freely moving organic chains, the polymer forms thick hydrophobic walls (ca 10 nm) [25]. The liquid phase retained is limited, although the swelling degree is still 8.2 (Fig.1).…”

Section: Dopamine Hydrochloridementioning

confidence: 99%

Host–guest interactions in poly(N-isopropylacrylamide) gel

Manek

Domján

Menyhárd

et al. 2015

J Therm Anal Calorim

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Responsive hydrogels are one of the most frequently proposed vehicles for targeted and controlled drug delivery. Interaction between the transported drug and the three-dimensional polymer network could compromise the kinetics and the efficiency of delivery in thermoresponsive polymers. Poly(N-isopropylacrylamide) (PNIPA) gel was equilibrated with excess 500 mM aqueous solutions of three model drug molecules, phenol, ibuprofen and dopamine. These molecules affect the swelling properties of PNIPA in different ways. After determining the drug uptake and drying to constant mass the loaded samples were studied with simultaneous thermal analysis (STA). The difference in thermal response is interpreted in terms of the different typical molecular interactions in these systems under confined conditions. For phenol and dopamine the water -phenol and dopamine -dopamine interactions, respectively, are stronger than that between the guest and polymer. For ibuprofen -PNIPA the synergy in the thermal decomposition may stem from a strong polymeribuprofen relation.

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Phase Separation Induced Mechanical Transition of Poly(N-isopropylacrylamide)/Water Isochore Gels

Cited by 207 publications

References 10 publications

Surface Chemical and Mechanical Properties of Plasma-Polymerized N-Isopropylacrylamide

Surface Chemical and Mechanical Properties of Plasma-Polymerized N-Isopropylacrylamide

Polyurethane/Poly(2-(Diethyl Amino)Ethyl Methacrylate) blend for drug delivery applications

Host–guest interactions in poly(N-isopropylacrylamide) gel

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