Reversible phase transitions in polymer gels induced by radiation forces

被引:275
作者
Juodkazis, S
Mukai, N
Wakaki, R
Yamaguchi, A
Matsuo, S
Misawa, H
机构
[1] Univ Tokushima, Grad Sch Engn, Dept Ecosyst Engn, Tokushima 7708506, Japan
[2] Univ Tokushima, Satellite Venture Business Lab Photon Nanomat, Tokushima 7708506, Japan
关键词
D O I
10.1038/35041522
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Many polymer gels undergo reversible, discontinuous volume changes in response to changes in the balance between repulsive intermolecular forces that act to expand the polymer network and attractive forces that act to shrink it. Repulsive forces are usually electrostatic or hydrophobic in nature, whereas attraction is mediated by hydrogen bonding or van der Waals interactions. The competition between these counteracting forces, and hence the gel volume(1-3), can thus be controlled by subtle changes in parameters such as pH (ref. 4), temperature(5), solvent composition(6) or gel composition(7). Here we describe a more direct influence on this balance of forces, by showing that the radiation force generated by a focused laser beam induces reversible shrinkage in polymer gels. Control experiments confirm that the laser-induced volume phase transitions are due to radiation forces, rather than local heating, modifying the weak interactions in the gels, in agreement with previous observations of light-induced chain association in polymer solutions(8,9). We rnd that, owing to shear-relaxation processes(10), gel shrinkage occurs up to several tens of micrometres away from the irradiation spot, raising the prospect that the combination of stimuli-responsive polymer gels and laser light might lead to new gel-based systems for applications such as actuating or sensing.
引用
收藏
页码:178 / 181
页数:5
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