Laser-activated shape memory polymer microactuators for treating stroke

Maitland, Duncan J.; Wilson, Thomas S.; Schumann, Daniel L; Baer, G.

doi:10.1109/leos.2002.1134078

Cited by 13 publications

(15 citation statements)

References 8 publications

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“…Athermally induced SMEs are caused by afebrile stimuli including light, electricity, magnetism, and solution-triggered actuation [58,69,76]. Wu et al [132] reported a biodegradable light-sensitive SMP consisting of block polyurethanes and pendant cinnamamide moieties.…”

Section: Athermally Induced Smesmentioning

confidence: 99%

Nanocellulose and Its Application for Shape-Memory Materials

Fu¹,

Tian²

2015

Advanced Structured Materials

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Nanocellulose (NC) has been attracting a great deal of interest as promising candidates for bionanocomposite due to their appealing intrinsic properties, such as low density, high surface area, and mechanical strength. In view of countless publications on nanocellulose composites already, this chapter concentrates on application of nanocellulose for reinforcing shape-memory composites. Shape-memory composites enable high-recovery stress levels and various functions due to their different components. The shape-memory behavior is also dependent on the size, shape, and concentration of the fillers. The effect of nanocellulose in these composites is determined by different shape-memory switches and interactions between nanocellulose and matrices. A challenge of using NC in shape-memory composites is the lack of compatibility between hydrophobic matrices and hydrophilic NCs. Various chemical modification methods have been explored to address this hurdle. In this chapter, we summarized the effect of nanocellulose on the deformation mechanism of shape-memory materials, with a particular focus on thermo-and water-sensitive switches. The application of shape-memory composites based on nanocellulose is also discussed.

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Section: Athermally Induced Smesmentioning

confidence: 99%

Nanocellulose and Its Application for Shape-Memory Materials

Fu¹,

Tian²

2015

Advanced Structured Materials

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“…Narendra Kumar et al -eXPRESS Polymer Letters Vol.6, No.1 (2012) [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] …”

Section: Recovery By Environmental Heatingmentioning

confidence: 99%

“…Non contact initiation of SME was realized by irradiation with infrared light [29][30][31], applying radio-frequency (RF) [32], or an alternating magnetic field [4,10,[33][34][35][36]. The magnetically triggered SME can be characterized by a specific switching magnetic field strength H sw , which needs to be exceeded to induce the shape change [10].…”

mentioning

confidence: 99%

Shape-memory properties of magnetically active triple-shape nanocomposites based on a grafted polymer network with two crystallizable switching segments

Kumar¹,

Kratz²,

Behl³

et al. 2012

Express Polym. Lett.

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Shape-memory polymers (SMP) and composites thereof belong to the class of actively moving polymers, which have the capability of storing one (dualshape) [1][2][3][4][5][6], two (triple-shape) [7][8][9][10][11][12][13] or multiple (multiple-shape) [14] stable temporary shapes and recover their original or other temporary shapes when exposed to an external stimulus. The field of SMP research has developed rapidly over the last years [6,[15][16][17][18][19][20][21][22][23][24][25] and it has become apparent that these functional polymers are motivating novel applications. Thermo-sensitive SMP contain physical or chemical network-points, which determine their original shape, while each temporary shape is fixed by switching domains associated to a thermal transition temperature T trans , that can be a glass transition (T g ) or a melting transition (T m ) [16,17]. The process for programming of a temporary shape is called 'shapememory creation procedure' (SMCP) and can be realized e.g. by deforming the material to an extension of ! m at T > T trans and cooling to T < T trans while keeping the deformation, which then is fixed temporarily by solidification of the related set of switching domains [26]. The recovery of the original shape is named shape-memory effect (SME), which is typically induced by increasing the environmental temperature (T env ) [3,5,27,28] Abstract. Thermo-sensitive shape-memory polymers (SMP), which are capable of memorizing two or more different shapes, have generated significant research and technological interest. A triple-shape effect (TSE) of SMP can be activated e.g. by increasing the environmental temperature (T env ), whereby two switching temperatures (T sw ) have to be exceeded to enable the subsequent shape changes from shape (A) to shape (B) and finally the original shape (C). In this work, we explored the thermally and magnetically initiated shape-memory properties of triple-shape nanocomposites with various compositions and particle contents using different shape-memory creation procedures (SMCP). The nanocomposites were prepared by the incorporation of magnetite nanoparticles into a multiphase polymer network matrix with grafted polymer network architecture containing crystallizable poly(ethylene glycol) (PEG) side chains and poly(!-caprolactone) (PCL) crosslinks named CLEGC. Excellent triple-shape properties were achieved for nanocomposites with high PEG weight fraction when two-step programming procedures were applied. In contrast, single-step programming resulted in dual-shape properties for all investigated materials as here the temporary shape (A) was predominantly fixed by PCL crystallites.

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“…Different kinds of actuation methods are explored including heat [7], light [8,9], electricity [10,11], magnetic field [12,13], or solvent [14][15][16]. Electrically actuating SMPs by electrical resistive heating has been intensively studied.…”

Section: Introductionmentioning

confidence: 99%

Electrical actuation and shape recovery control of shape-memory polymer nanocomposites

Liang

Sivilli

Gou

et al. 2013

International Journal of Smart and Nano Materials

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Shape-memory polymers (SMPs) are one of the most popular smart materials due to their light weight and high elastic deformation capability. The synergistic effect of carbon nanofiber (CNF) and carbon nanofiber paper (CNFP) on the electro-actuation of SMP nanocomposites was studied. The electrical conductivity of SMPs was significantly improved by incorporating CNF and CNFP into them. The dynamic mechanical analysis result reveals good thermal stability of SMP nanocomposites even after they were mixed with CNFs. A vision-based control system is designed to precisely control the shape recovery of SMP composites. Any quasi-state shape between the permanent shape and a temporary shape can be achieved by adjusting the electrical energy input. Experimental results demonstrated that (1) compared with the baseline material, the full recovery time of the SMP nanocomposites was decreased by 1000% to less than 80 s; (2) a good repeatability was shown in the developed vision system in 10 experimental trials and the accuracy of the controlled deflection angle of SMPs was within a 5% error bound.

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Laser-activated shape memory polymer microactuators for treating stroke

Cited by 13 publications

References 8 publications

Nanocellulose and Its Application for Shape-Memory Materials

Nanocellulose and Its Application for Shape-Memory Materials

Shape-memory properties of magnetically active triple-shape nanocomposites based on a grafted polymer network with two crystallizable switching segments

Electrical actuation and shape recovery control of shape-memory polymer nanocomposites

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