New directions in the chemistry of shape memory polymers

Berg, Gayla J.; McBride, Matthew K.; Wang, Chen; Bowman, Christopher N.

doi:10.1016/j.polymer.2014.07.052

Cited by 175 publications

(130 citation statements)

References 206 publications

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“…SMPs are a type of polymeric smart materials which are able to remember their original shape after being deformed, and recover it as a response to an external stimulus. Heat is one of the most common stimulus, although SMPs could be also triggered by light and moisture, among others [1,4]. Generally, thermally-activated SMPs consist of two phases, the permanent phase and the thermally reversible phase.…”

Section: Introductionmentioning

confidence: 99%

Thermally-responsive biopolyurethanes from a biobased diisocyanate

Calvo‐Correas

Santamaria‐Echart

Saralegi

et al. 2015

European Polymer Journal

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Section: Introductionmentioning

confidence: 99%

Thermally-responsive biopolyurethanes from a biobased diisocyanate

Calvo‐Correas

Santamaria‐Echart

Saralegi

et al. 2015

European Polymer Journal

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“…The SM behavior of segmented PUs was early recognized thereby credit should be given to Tobushi et al [12]. Nowadays, already a large body of works addressed the preparation and characterization of shape memory PUs (SMPUs) [13][14][15][16]. Research strategies focus now on the creation of multifunctional polymers [17,18].…”

Section: Introductionmentioning

confidence: 99%

Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type

Lakatos¹,

Czifrák²,

Papp³

et al. 2016

Express Polym. Lett.

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Abstract. Segmented linear polyurethanes (PUs) containing Diels-Alder (DA) adduct were synthesized in toluene solution from poly("-caprolactone) (PCL, M n = 10, 25 and 50 kg/mol), diisocyanate (methylene diphenyl diisocyanate (MDI), 2,4-toluene diisocyanate (TDI), 1,6-hexamethylenediisocyanate, (HDI)), furfurylamine (FA) and bismaleimide (BMI). The order of the segments in the PUs was -PCL-MDI-FA-BMI-. The PUs were characterized by size-exclusion chromatography (SEC), different spectroscopic ( 1 H-NMR, attenuated total reflectance Fourier-transform infrared, AT-FTIR), thermal and mechanical analysis (differential scanning calorimetry, DSC, dynamical mechanical analysis, DMA). The DA and retro-DA reactions were identified by 1 H-NMR for both the synthesized PU and the coupling components (i.e. FA and BMI). Tensile mechanical and shape memory (SM) properties of the PUs were also determined. The DA coupling in the PU was improved by heat treatment above the melting temperature (T m ) of PCL. DMA traces showed a plateau-like region above T m of PCL confirming the presence of a physical network the netpoints of which are given by the hard segments including the DA couplers. This feature suggested good SM behavior that was confirmed both qualitatively and quantitatively.

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“…Upon heating, the catalyst is 96 released and the reaction occurs rapidly, resulting in 97 homogeneous and well-defined network structures. 98 This enhances the mechanical properties (strength 99 and deformability) of the shape-memory materials 100 developed [22].…”

mentioning

confidence: 99%

New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

2016

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Our research group has recently found excellent shape-memory response in “thiol-epoxy” thermosets obtained with click-chemistry. In this study, we use their well-designed, homogeneous and tailorable network structures to investigate parameters for better control of the shape-recovery process. We present a new methodology to analyse the shape-recovery process, enabling easy and efficient comparison of shape-memory experiments on the programming conditions. Shape-memory experiments at different programming conditions have been carried out to that end. Additionally, the programming process has been extensively analysed in uniaxial tensile experiments at different shape-memory testing temperatures. The results showed that the shape-memory response for a specific operational design can be optimized by choosing the correct programming conditions and accurately designing the network structure. When programming at a high temperature (T » Tg), under high network mobility conditions, high shape-recovery ratios and homogeneous shape-recovery processes are obtained for the network structure and the programmed strain level (eD). However, considerably lower stress and strain levels can be achieved. Meanwhile, when programming at temperatures lower than Tg, considerably higher stress and strain levels are attained but under low network mobility conditions. The shape-recovery process heavily depends on both the network structure and eD. Network relaxation occurs during the loading stage, resulting in a noticeable decrease in the shape-recovery rate as eD increases. Moreover, at a certain level of strain, permanent and non-recoverable deformations may occur, impeding the completion and modifying the whole path of the shape-recovery process.Postprint (author's final draft

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New directions in the chemistry of shape memory polymers

Cited by 175 publications

References 206 publications

Thermally-responsive biopolyurethanes from a biobased diisocyanate

Thermally-responsive biopolyurethanes from a biobased diisocyanate

Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type

New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

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