Enabling Applications of Covalent Adaptable Networks

The ability to behave in a fluidlike manner fundamentally separates thermoset and thermoplastic polymers. Bridging this divide, covalent adaptable networks (CANs) structurally resemble thermosets with permanent covalent crosslinks but are able to flow in a manner that resembles thermoplastic behavior only when a dynamic chemical reaction is active. As a consequence, the rheological behavior of CANs becomes intrinsically tied to the dynamic reaction kinetics and the stimuli that are used to trigger those, including temperature, light, and chemical stimuli, providing unprecedented control over viscoelastic properties. CANs represent a highly capable material that serves as a powerful tool to improve mechanical properties and processing in a wide variety of polymer applications, including composites, hydrogels, and shape-memory polymers. This review aims to highlight the enabling material properties of CANs and the applied fields where the CAN concept has been embraced.

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Poly(ε-caprolactone)-based shape memory polymers crosslinked by polyhedral oligomeric silsesquioxane

RSC Advances ◽

10.1039/c6ra20431g ◽

2016 ◽

Vol 6 (93) ◽

pp. 90212-90219 ◽

Cited By ~ 21

Author(s):

Pengfei Yang ◽

Guangming Zhu ◽

Xuelin Shen ◽

Xiaogang Yan ◽

Jing Nie

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Shape Memory ◽

Polyhedral Oligomeric Silsesquioxane ◽

Shape Memory Polymers ◽

Complete Recovery ◽

Memory Network ◽

Oligomeric Silsesquioxane

A POSS–PCL shape memory network is synthesized. The cage-like POSS not only serves as a chemical netpoint, also causes improvement in mechanical properties. Optimized networks exhibit both excellent tensile strength and nearly complete recovery.

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Shape-Memory Polymers for Biomedical Applications

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.54.96 ◽

2008 ◽

Vol 54 ◽

pp. 96-102 ◽

Cited By ~ 33

Author(s):

Andreas Lendlein ◽

Marc Behl

Keyword(s):

Shape Memory ◽

Material Properties ◽

Biomedical Applications ◽

Traditional Approach ◽

Shape Change ◽

Shape Memory Polymers ◽

Thermally Induced ◽

Wide Range ◽

Multifunctional Polymers ◽

Suitable Process

Most polymers used in clinical applications today are materials that have been developed originally for application areas other than biomedicine. On the other side, different biomedical applications are demanding different combinations of material properties and functionalities. Compared to the intrinsic material properties, a functionality is not given by nature but result from the combination of the polymer architecture and a suitable process. Examples for functionalities that play a prominent role in the development of multifunctional polymers for medical applications are biofunctionality (e.g. cell or tissue specificity), degradability, or shape-memory functionality. In this sense, an important aim for developing multifunctional polymers is tailoring of biomaterials for specific biomedical applications. Here the traditional approach, which is designing a single new homo- or copolymer, reaches its limits. The strategy, that is applied here, is the development of polymer systems whose macroscopic properties can be tailored over a wide range by variation of molecular parameters. The Shape-memory capability of a material is its ability to trigger a predefined shape change by exposure to an external stimulus. A change in shape initiated by heat is called thermally-induced shape-memory effect. Thermally, light-, and magnetically induced shape-memory polymers will be presented, that were developed especially for minimally invasive surgery and other biomedical applications. Furthermore triple-shape polymers will be introduced, that have the capability to perform two subsequent shape changes. Thus enabling more complex movements of a polymeric material.

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