Laser-controlled phase transition of aqueous poly(N-isopropyl-acrylamide) solution in micrometer domain

1994 ◽  
pp. 79-92 ◽  
Author(s):  
N. Kitamura ◽  
M. Ishikawa ◽  
H. Misawa ◽  
R. Fujisawa
Keyword(s):  
Phase Transition ◽  
Isopropyl Acrylamide ◽  
Acrylamide Solution

Necklace-like microstructure in shallow-quenched aqueous solutions of poly(n-isopropylacrylamide), detected by advanced small-angle neutron scattering methods

Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 671-682 ◽  
Author(s):  
Satoshi Koizumi ◽  
Masahiko Annaka ◽  
Dietmar Schwahn
Keyword(s):  
Phase Transition ◽  
Aqueous Solutions ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Isopropyl Acrylamide

The microstructure of aqueous poly(N-isopropyl acrylamide) (PNIPA) gel and solution was investigated by small-angle neutron scattering (SANS) in the vicinity of the gel volume phase transition at TV (= 34 °C).

scholarly journals Small angle X-ray scattering study of poly(N-isopropyl acrylamide) based cryogels near the volume-phase transition temperature

2010 ◽  
Vol 247 ◽  
pp. 012041 ◽  
Author(s):  
Mohand Chalal ◽  
Françoise Ehrburger-Dolle ◽  
Isabelle Morfin ◽  
Maria-Rosa Aguilar de Armas ◽  
Maria-Luisa López ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Small Angle ◽  
Volume Phase Transition ◽  
X Ray ◽  
Volume Phase ◽  
X Ray Scattering ◽  
Isopropyl Acrylamide ◽  
Scattering Study

Controlled Release of Growth Factor Using Poly(N-Isopropyl Acrylamide)Copolymer Hydrogels with Different Volume Phase Transition Temperatures

2005 ◽  
Vol 277-279 ◽  
pp. 77-81
Author(s):  
Young A Han ◽  
Jeong Ok Lim ◽  
Jin Hyun Choi ◽  
Byung Chul Ji
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Crosslinking Agent ◽  
Volume Phase Transition ◽  
Release Behavior ◽  
Volume Phase ◽  
Volume Phase Transition Temperature ◽  
Isopropyl Acrylamide ◽  
Phase Transition Temperatures

The release behavior of the basic fibroblast growth factor (bFGF) from copolymer hydrogels of N-isopropyl acrylamide (NIPAAm) and sodium methacrylate (SMA) was investigated in relation to the volume phase transition temperatures, which was increased by the incorporation of SMA. In the case of the copolymer hydrogels, a higher volume phase transition temperature was obtained when poly(ethylene glycol) diacrylate (PEGDA) was used as the crosslinking agent, suggesting that the chain length of the crosslinking agent has a significant affect on the volume phase transition temperature of a P(NIPAAm-co-SMA) hydrogel. The concentration of bFGF released from the hydrogels with PEGDA increased relative to the water content, thereby showing a dependence on the volume phase transition temperature. Hence, the release behavior of bFGF from the PNIPAAm and P(NIPAAm-co-SMA) hydrogels was found to be affected by the volume phase transition temperature, which can be easily controlled by changing the comonomer, monomer feed ratio, and crosslinking agent.

scholarly journals POSS Hybrid Robust Biomass IPN Hydrogels with Temperature Responsiveness

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 524 ◽  
Author(s):  
Yi Chen ◽  
Yueyun Zhou ◽  
Wenyong Liu ◽  
Hejie Pi ◽  
Guangsheng Zeng
Keyword(s):  
Phase Transition ◽  
Tensile Deformation ◽  
Drug Loading ◽  
Synthesis And Characterization ◽  
Volume Phase Transition ◽  
Target Drug ◽  
Isopropyl Acrylamide ◽  
Biomedical Field ◽  
Oligomeric Silsesquioxane

In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca2+ ions to meet greater application demand, a strategy was designed to structure novel SA-based gels (named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl2 and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si–O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

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