Table 2.

Summary of materials with shape memory properties, their activation methods and the most outstanding reported features.

SMP Material	Tested Activation Method	Features	Citation
Butadiene–styrene tri-block copolymer/PCL	Heat/water	Polymer blend with elastomeric and shape memory properties.	[96]
Norland Optical Adhesive 63 (propietary)	Heat	$T_g$  gradients have been reported.	[97]
Silsesquioxane nanoparticles/PLA	Heat	Long-term (>1 year) shape storage.	[98]
PCL-coated Fe${}_3$O${}_4$ /oligo(PCL) DMA/BA	Electromagnetism	Remote activation without reaching temperatures higher than $T_g$.	[90]
Perfluorosulphonic acid ionomer	Heat	Multi-shape memory effect with distinctive thermal states.	[99]
Phenylboronic-acid-grafted alginate/PVA	pH	Stable shape storage at specific pH and sugar contents.	[92]
PU/carbon nanopowder	Joule heating	Carbon powder provides conductivity for electrical actuation.	[100,101]
Poly(propylene sebacate)	Heat	Ecologically sustainable material.	[102]
Polydopamine/PCL	Heat	Great thermal conductivity.	[103]
PLA/PPy	Joule heating	Polypyrrole provides conductivity for electrical triggering of shape recovery. PLA is biodegradable.	[51]
Olylactide-co-poly(glycolide-co-caprolactone)	Heat	Highly biodegradable.	[104]
Polymethyl metracrylate/PEG	Heat	Multi-shape memory effect with distinctive thermal states.	[105]
Polystyrene	Heat/IR light	IR activation provides a contactless actuation method (less invasive). Material can also be applied in catheter design. Self-healing properties.	[89,106]
Polystyrene/carbonanotubes	Electromagnetism	Microwave activation provides a minimally invasive actuation method.	[91]
Polystyrene/copolyester particulates	Heat	Self-healing properties.	[107]
PU	Moisture/pH/IR Light	Extensively applied for in-vitro and in-vivo occlusion of aneurysms. Furthermore, used in stent design. Facile control of $T_g$ and mechanical properties. Can be designed to be responsive to moisture, IR light, pH, and heat. Multi-shape memory effect with distinctive thermal states can also be achieved.	[55,81,94,95,108,109,110,111]
PU/CNT	Heat/Joule heating	CNTs provide conductivity for electrical triggering of shape recovery.	[58,85]
PU/PEG	Heat	Multi-shape memory effect. Facile $T_g$ tuning.	[112]
PU/PPy	Joule heating	Polypyrrole provides conductivity for electrical triggering of shape recovery. PLA is biodegradable.	[83,87,88]
Silver nanowire/PET	Heat	Reported for the design of light-emitting diodes.	[113]
SiO${}_2$/PCL	Heat	SiO${}_2$ macroparticles provide improved mechanical properties (high strain). Biodegradable.	[114]
Tert-BA/di(ethylene glycol) diacrylate	Heat	It can be fabricated with stereolithography techniques.	[115]
$\beta$-CDAlg/DETA-Alg	pH	Stable shape storage at specific pH. Biodegradable and biocompatible.	[93]