Thermal Annealing to Modulate the Shape Memory Behavior of a Biobased and Biocompatible Triblock Copolymer Scaffold in the Human Body Temperature Range

Merlettini, Andrea; Gigli, Matteo; Ramella, Martina; Gualandi, Chiara; Soccio, Michelina; Boccafoschi, Francesca; Munari, Andrea; Lotti, Nadia; Focarete, Maria Letizia

doi:10.1021/acs.biomac.7b00644

Cited by 17 publications

(15 citation statements)

References 55 publications

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“…Under thermal annealing above T trans , the high mobility of the chains associated with the dissociation of the hydrogen bonds interaction between hard and soft segments contributes to phase separation and formation of the HD and SDs as consequence 17,18,30,31 . This phenomenon has shown a significant influence in the SME by controlling the time and annealing temperature ( T a ), as previous reported in literature 25,28,32–34 …”

Section: Introductionmentioning

confidence: 61%

Unraveling the impact of phase separation induced by thermal annealing on shape memory effect of polyester‐based thermoplastic polyurethane

Valim

Oliveira

Vasconcelos

et al. 2021

J of Applied Polymer Sci

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In this study polyester‐based thermoplastic polyurethane (TPU) samples were annealed at 110°C for 0, 8, 16, and 24 h. To elucidate the relationship between the hard and soft phase separation and the shape memory properties, the samples were characterized within a rheometer, by selecting well defined thermal cycles. The results showed an enhancement of the shape recovery ratio (Rr ~ 65%) for all the annealed samples, when compared to the non‐annealed TPU (Rr ~ 60%). This behavior was attributed to the modifications of hard‐soft domain morphology occurring during the thermal annealing treatment, as it was shown both by differential scanning calorimetry with the shift in thermal transitions toward higher temperature, due the formation of new short‐range ordered hard domains and infrared spectroscopy, with the increase in degree of phase separation. Analyzing small‐angle X‐ray scattering, the decrease of the invariant also confirmed the enhancement of short‐range domains. The formation of these new short‐range domains acted as crosslinking points in TPU's morphology leading to an increase in stiffness, presented by higher Young and storage modulus. Based on these results, a model mechanism is proposed to correlate the morphology and structure of the annealed materials with their shape memory effect.

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Section: Introductionmentioning

confidence: 61%

Unraveling the impact of phase separation induced by thermal annealing on shape memory effect of polyester‐based thermoplastic polyurethane

Valim

Oliveira

Vasconcelos

et al. 2021

J of Applied Polymer Sci

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“…The second problem can be addressed via copolymerization of monomers with different melting temperatures. [ 18–20 ] However, this involves chemical composition and biocompatibility variation and yet, copolymer modulus is limited by chain entanglements to >10 5 Pa. [ 21,22 ]…”

Section: Figurementioning

confidence: 99%

Tissue‐Adaptive Materials with Independently Regulated Modulus and Transition Temperature

et al. 2020

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Various types of clinical complications may emerge when a medical device (catheter, microelectrode, or microneedle patch) is deployed to the human body. It has been widely recognized that mechanical mismatch between an implant and a host tissue is one of the leading factors for adverse effects such as irritation and inflammation, which is evident in orthopedic, [1] neural, [2,3] and reconstructive implants. [4] It is generally desired that an implant material precisely matches Young's modulus of the surrounding tissue that may range between E ≈ 10 2 Pa of supersoft brain and adipose tissues to E ≈ 10 5 Pa of muscle and skin. However, forceful implantation of biomedical devices such as piercing, insertion or twisting impose significant mechanical stresses on the device. [5-8] Therefore a certain rigidity is desired to prevent device failure, minimize tissue damage, and simplify storage and handling procedures. [9,10] This presents an oxymoronic challenge for an ideal implant: designing an adaptive material that readily penetrates tissue, but transitions into a tissue-soft implant upon insertion into the body (Figure 1A). Thermoplastics are one of the most commonly used materials possessing a well-defined transition between hard and soft states with Young's moduli of E hard ≈ 1 GPa and E soft ≈ 1 MPa, respectively (Figure 1B, Table S1, Supporting Information). However, conventional thermoplastic materials have two problems: i) E soft ≈ 1 MPa is significantly higher than soft tissue modulus ranging within 10 2-10 5 Pa and ii) softening (melting or glass) transition temperature of high molecular weight polymers cannot be tuned without altering their chemical composition. It is even more challenging to adjust the mechanical and thermal properties independently of each other. The softness issue alone could be resolved by using different types of bioinspired polymeric gels. [14-17] However, not only it is difficult to prepare gels with a sharp GPa-to-kPa transition (Figure 1C, Table S2, Supporting Information), their solvent fraction instigates uncontrolled leaching inside the body, [13] which causes various health risks. The second problem can be addressed via copolymerization of monomers with different melting temperatures. [18-20] However, this involves chemical composition and biocompatibility variation and yet, copolymer modulus is limited by chain entanglements to >10 5 Pa. [21,22] The ability of living species to transition between rigid and flexible shapes represents one of their survival mechanisms, which has been adopted by various human technologies. Such transition is especially desired in medical devices as rigidity facilitates the implantation process, while flexibility and softness favor biocompatibility with surrounding tissue. Traditional thermoplastics cannot match soft tissue mechanics, while gels leach into the body and alter their properties over time. Here, a single-component system with an unprecedented drop of Young's modulus by up to six orders of magnitude from the GPa to kPa level at a control...

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“…On the other hand, by exploiting the hydroxyl terminal groups of a (co)polyester for the ring opening reaction of a lactone, triblock copolymers can be easily prepared ( Figure 2B). These latter can be then chain-extended with diisocyanates to form alternating multiblock copolymers [57].…”

Section: Chain-extension Techniquementioning

confidence: 99%

Recent Advances in Nanocomposites Based on Aliphatic Polyesters: Design, Synthesis, and Applications in Regenerative Medicine

et al. 2018

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In the last decade, biopolymer matrices reinforced with nanofillers have attracted great research efforts thanks to the synergistic characteristics derived from the combination of these two components. In this framework, this review focuses on the fundamental principles and recent progress in the field of aliphatic polyester-based nanocomposites for regenerative medicine applications. Traditional and emerging polymer nanocomposites are described in terms of polymer matrix properties and synthesis methods, used nanofillers, and nanocomposite processing and properties. Special attention has been paid to the most recent nanocomposite systems developed by combining alternative copolymerization strategies with specific nanoparticles. Thermal, electrical, biodegradation, and surface properties have been illustrated and correlated with the nanoparticle kind, content, and shape. Finally, cell-polymer (nanocomposite) interactions have been described by reviewing analysis methodologies such as primary and stem cell viability, adhesion, morphology, and differentiation processes.

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Thermal Annealing to Modulate the Shape Memory Behavior of a Biobased and Biocompatible Triblock Copolymer Scaffold in the Human Body Temperature Range

Cited by 17 publications

References 55 publications

Unraveling the impact of phase separation induced by thermal annealing on shape memory effect of polyester‐based thermoplastic polyurethane

Unraveling the impact of phase separation induced by thermal annealing on shape memory effect of polyester‐based thermoplastic polyurethane

Tissue‐Adaptive Materials with Independently Regulated Modulus and Transition Temperature

Recent Advances in Nanocomposites Based on Aliphatic Polyesters: Design, Synthesis, and Applications in Regenerative Medicine

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