Shape‐Memory Effects in Polymer Networks Containing Reversibly Associating Side‐Groups

Li, Jiahui; Viveros, James A.; Wrue, Michelle; Anthamatten, Mitchell

doi:10.1002/adma.200602260

Cited by 270 publications

(252 citation statements)

References 31 publications

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“…Some other methods such as using transitions other than crystallization and vitrification for shape fixing have also been reported. [16][17][18] Recently, a new method of designing SMEs with both excellent shape memory property and balanced elastomeric behavior (high elastomers content) has been reported by Luo and Mather [19] They fabricated SMEs by incorporating electrospun, non-woven thermoplastic fibers (serving as the switch phase) into an elastomers matrix (providing the elastic memory). This method is instructive and shows its versatility in their following studies.…”

Section: Introductionmentioning

confidence: 99%

A New Strategy to Prepare Polymer‐based Shape Memory Elastomers

Song

Feng

2011

Macromol. Rapid Commun.

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A new strategy that utilizes the microphase separation of block copolymer and phase transition of small molecules for preparing polymer-based shape memory elastomer has been proposed. According to this strategy, a novel kind of shape memory elastomer comprising styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) and paraffin has been prepared. Because paraffins are midblock-selective molecules for SEBS, they will preferentially enter and swell EB blocks supporting paraffins as an excellent switch phase for shape memory effect. Microstructures of SEBS/paraffin composites have been characterized by transmission electron microscopy, polarized light microscopy, and differential scanning calorimetry. The composites demonstrate various phase morphologies with regard to different paraffin loading. It has been found that under low paraffin loading, all the paraffins precisely embed in and swell EB-rich domains. While under higher loading, part of the paraffins become free and a larger-scaled phase separation has been observed. However, within wide paraffin loadings, all composites show good shape fixing, shape recovery performances, and improved tensile properties. Compared to the reported methods for shape memory elastomers preparation, this method not only simplifies the fabrication procedure from raw materials to processing but also offers a controllable approach for the optimization of shape memory properties as well as balancing the rigidity and softness of the material.

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Section: Introductionmentioning

confidence: 99%

A New Strategy to Prepare Polymer‐based Shape Memory Elastomers

Song

Feng

2011

Macromol. Rapid Commun.

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“…11 UPy groups have been used in acrylate networks to allow fast relaxation of stresses at elevated temperatures in materials designed to display shape memory properties. 8 Our interest is in the slower relaxation of stresses at room temperature. To this end, we introduced the noncovalent UPy cross-links in polyester-polyurethane networks, which were inspired by the two-component polyesterpolyurethane systems that constitute some of the most important commercial coatings.…”

Section: Introductionmentioning

confidence: 99%

“…In numerous studies in polymer chemistry, 2,3 biomedical applications, [4][5][6] and materials science, 7,8 UPy units act as robust, selective, and directional hydrogen-bonding systems. Their high dimerization strength (ΔG°d im = -35 kJ/mol in chloroform) is intermediate between the bond strength of covalent and of most other noncovalent bonds.…”

Section: Introductionmentioning

confidence: 99%

Preemptive Healing through Supramolecular Cross-Links

et al. 2009

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The ability of highly cross-linked thermoset materials to relax stresses by network chain segment mobility above or just below T g is generally limited. We describe materials in which some of the crosslinks have been replaced by dimers of quadruple hydrogen-bonding ureidopyrimidinone (UPy) moieties, which act as reversible cross-links. Materials based on mixtures of ε-caprolactone and L-lactic acid, and containing different ratios of covalent and UPy dimer cross-links, were synthesized, and their thermal and mechanical properties were tested by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The presence of reversible cross-links results in superior relaxation of stresses even below T g , as witnessed by the creep and stress relaxation behavior. These properties bode well for potential applications, e.g., in coatings technology.

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“…29,30 To broaden the scope and applicability of supramolecular polymer chemistry, many new strongly hydrogen-bonding moieties have been synthesized [31][32][33][34][35][36][37] and incorporated into networkforming materials. [12][13][14][15][38][39][40][41] The strength and specificity of multiple-hydrogen-bonded (MHB) groups vary widely, from weakly complementary pyridine-phenol pairs 42 to extremely strong, self-complementary 6-H-bonded dimers. 31 The 2-ureido-4[1H]-pyrimidinone (UPy) group first reported by Sijbesma et al 12 was developed as a synthetically accessible, exceptionally strong (K dim = 6 Â 10 7 M -1 in CDCl 3 ) quadruple-hydrogenbonded dimer in order to create highly thermally responsive polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

Model Transient Networks from Strongly Hydrogen-Bonded Polymers

Feldman¹,

Kade²,

Meijer³

et al. 2010

Macromolecules

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Random copolymers consisting of n-butyl acrylate backbones with quadruple hydrogenbonding side chains based on 2-ureido-4[1H]-pyrimidinone (UPy) have been synthesized via controlled radical polymerization and postpolymerization functionalization. Through this synthetic strategy high UPy monomer content (15 mol %) can be reached while maintaining low polydispersity and excellent control over molecular weight, providing model reversible networks with well-defined molecular architecture. Despite low T g s and a lack of entanglements or crystallinity, these materials behave as thermoplastic elastomers through the strong but reversible association of UPy groups. Bulk properties such as the plateau modulus, tensile modulus, and relaxation time scale are primarily determined by the average distance between UPy's along the chain. Starting from a difunctional initiator, triblock copolymers can also be synthesized containing a homopolymer midblock and random copolymer end blocks, effectively concentrating the hydrogen-bonding groups near the chain ends. By controlling both the average composition and distribution of UPy's along the polymer chain, macroscopic material properties such as stiffness and resistance to creep can be independently tuned.

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Shape‐Memory Effects in Polymer Networks Containing Reversibly Associating Side‐Groups

Cited by 270 publications

References 31 publications

A New Strategy to Prepare Polymer‐based Shape Memory Elastomers

A New Strategy to Prepare Polymer‐based Shape Memory Elastomers

Preemptive Healing through Supramolecular Cross-Links

Model Transient Networks from Strongly Hydrogen-Bonded Polymers

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