Shape‐memory polymer networks from oligo(ϵ‐caprolactone)dimethacrylates

Lendlein, Andreas; Schmidt, Annette; Schroeter, Michael; Langer, Robert

doi:10.1002/pola.20598

Cited by 216 publications

(189 citation statements)

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“…Shape-memory properties such as strain fixity and strain recovery rate have been quantified in cyclic thermomechanical tensile experiments for different maximum elongations. 12 The photoset materials show excellent shape-memory properties with values for the strain recovery rate R r,tot. between 92 and 97% and average strain fixity rates R f between 86 and 97% after five cycles.…”

Section: Introductionmentioning

confidence: 98%

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Shape-Memory Polymer Networks from Oligo[(ε-hydroxycaproate)-co-glycolate]dimethacrylates and Butyl Acrylate with Adjustable Hydrolytic Degradation Rate

et al. 2007

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Degradable shape-memory polymer networks intended for biomedical applications were synthesized from oligo-[( -hydroxycaproate)-co-glycolate]dimethacrylates with glycolate contents between 0 and 30 mol % using a photopolymerization process. In addition AB copolymer networks were prepared by adding 60 wt % n-butyl acrylate as comonomer. All synthesized polymer networks are semicrystalline at room temperature. A melting transition T m between 18 and 53°C which can be used as switching transition for the shape-memory effect can be attributed to the crystalline poly( -hydroxycaproate) phase. At temperatures below T m the elastic properties are dominated by these physical cross-links. At temperatures higher than T m the E modulus of the amorphous polymer networks is lowered by up to 2 orders of magnitude, depending on the chemical cross-link density. Copolymer networks based on macrodimethacrylates with a M n of up to 13 500 g‚mol -1 and a maximum glycolate content of 21 mol % show quantitative strain recovery rates in stress-controlled cyclic thermomechanical experiments. Hydrolytic degradation experiments of polymer networks performed in phosphate buffer solution at 37°C show that the degradation rate can be accelerated by increasing the glycolate content and decelerated by the incorporation of n-butyl acrylate. IntroductionMaterials which obtain their functionality after application of a functionalization process such as that described for shapememory polymers can be referred to as functionalized materials. 1 An actual trend in polymer science is the design of materials which show multifunctionality, meaning an unexpected combination of material functionalizations such as the combination of hydrolytic degradability and shape-memory functionality. [2][3][4] The shape-memory effect results from the combination of the polymer architecture with a certain processing and programming technology. The permanent shape of shape-memory polymers is defined by physical or chemical cross-links, while switching segments formed by domains, which are associated with a thermal transition T trans. , enable the fixation of the temporary shape. 1,5 To obtain a defined shape change upon transition of a switching temperature T switch , the temporary shape has to be programmed by application of a thermomechanical treatment. Examples for polymers which combine shape-memory functionality and biodegradability are amorphous polyesterurethane networks based on poly(rac-lactide-co-glycolate) segments having a glass transition temperature T g around 55°C. 5 Poly-[(3-hydroxybutyrate)-co-(3-hydroxyvalerate) (35 mol % 3-hydroxyvalerate) obtained by a biotechnological process showed a shape-memory effect when samples which were programmed by a cold drawing were submitted to temperatures above 75°C. The melting transition used to trigger the shape-memory effect and to define the permanent shape simultaneously ranged from 37 to 115°C. 6 Examples for polymers showing a thermally induced shapememory effect which contain poly( -hydroxycaproate), being con...

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Section: Introductionmentioning

confidence: 98%

“…In this way the incorporation of easily hydrolizable glycolate ester bonds is supposed to produce polymer networks with accelerated hydrolytic degradability but still advantageous thermal and mechanical properties comparable to polymer networks and ABpolymer networks based on oligo( -hydroxycaproate) chain segments. 12,13 …”

Section: Introductionmentioning

confidence: 99%

Shape-Memory Polymer Networks from Oligo[(ε-hydroxycaproate)-co-glycolate]dimethacrylates and Butyl Acrylate with Adjustable Hydrolytic Degradation Rate

et al. 2007

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“…UV-induced crosslinking is another possibility. #-caprolactone diol oligomers can easily be converted into the related dimethacrylates which can be efficiently photocured [26]. During their SM programming T m of the PCL segments served as T trans .…”

Section: Chemical Networkmentioning

confidence: 99%

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Karger‐Kocsis

Kéki

2014

Express Polym. Lett.

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Shape memory (SM) biodegradable polymers (SMPs) and related composites are emerging smart materials in different applications. SMPs may adopt one (dual-shape), two (triple-shape) or several (multishape) stable temporary shapes and recover their permanent shape (or other temporary shapes in case of multi-shape versions) upon the action of an external stimulus. The external stimulus may be temperature, pH, water, light irradiation, redox condition etc. In most cases, however, the SMPs are thermally activated. The 'switching' or transformation temperature (T trans ), enabling the material to return to its permanent shape, is either linked with the glass transition (T g ) or with the melting temperature (T m ).Thus, SMPs are often subdivided based on their switch types into T g -or T m -based SMPs. As reversible 'switches' other mechanisms such as liquid crystallization and related transitions, supermolecular assembly/disassembly, irradiation-induced reversible network formation, formation and disruption of a percolation network, may also serve [1]. The permanent shape is guaranteed by physical or chemical network structures. The latter may be both on molecular and supramolecular levels. Linkages of these networks are termed net points. The temporary shape is created by mechanical deformation above T trans . In some cases the deformation temperature may be below Abstract. Shape memory polymers (SMPs) are capable of memorizing one or more temporary shapes and recovering to the permanent shape upon an external stimulus that is usually heat. Biodegradable polymers are an emerging family within the SMPs. This minireview delivers an overlook on actual concepts of molecular and supramolecular architectures which are followed to tailor the shape memory (SM) properties of biodegradable polyesters. Because the underlying switching mechanisms of SM actions is either related to the glass transition (T g ) or melting temperatures (T m ), the related SMPs are classified as T g -or T m -activated ones. For fixing of the permanent shape various physical and chemical networks serve, which were also introduced and discussed. Beside of the structure developments in one-way, also those in two-way SM polyesters were considered. Adjustment of the switching temperature to that of the human body, acceleration of the shape recovery, enhancement of the recovery stress, controlled degradation, and recycling aspects were concluded as main targets for the future development of SM systems with biodegradable polyesters.

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“…A polymer system consists of families of polymers, in which the macroscopic properties, such as thermal or mechanical properties, can be controlled almost independently from each other over a wide range, by the systematic variation of specific molecular parameters. Consequently, multifunctional materials requiring a specific combination for a certain application can be obtained by only a slight variation of the molecular structure or chemical composition in such a polymer system [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Shape-Memory Polymers for Biomedical Applications

Lendlein

Behl

2008

Advances in Science and Technology

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Abstract. 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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Shape‐memory polymer networks from oligo(ϵ‐caprolactone)dimethacrylates

Cited by 216 publications

References 40 publications

Shape-Memory Polymer Networks from Oligo[(ε-hydroxycaproate)-co-glycolate]dimethacrylates and Butyl Acrylate with Adjustable Hydrolytic Degradation Rate

Shape-Memory Polymer Networks from Oligo[(ε-hydroxycaproate)-co-glycolate]dimethacrylates and Butyl Acrylate with Adjustable Hydrolytic Degradation Rate

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Shape-Memory Polymers for Biomedical Applications

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