Coated shape memory polymer fibers for textile applications

Abstract

The present invention relates to the field of fibers, and in particular to a shape memory polymer fiber (SMPF) for textile or medical applications, which can maintain constant shape fixity and recovery even after multiple shape memory cycles. The present invention relates to a coated shape memory polymer fiber (cSMPF) (1) having a core fiber (10) containing a shape memory polymer fiber and a substantially inelastic covering yarn (20), wherein the covering yarn (20) is wound around the core fiber (10), and the maximum engineering strain (ε) of the core shape memory fiber is controlled. max ) is the yield strain (ε yield ) or less, thereby limiting the stretch or deformation of the textile and / or fabric comprising the core shape memory fiber and / or the coated shape memory fiber during programming or use, ensuring maximum recovery strain. Also disclosed are coated shape memory polymer fibers (cSMPF) (1), shape memory fibers, and methods of making shape memory textiles comprising coated shape memory polymer fibers (cSMPF).

Description

[Technical Field]

[0001] The present invention belongs to the field of shape memory fibers and relates to coated shape memory polymer fibers, their manufacturing method, and shape memory fabrics and shape memory textiles containing them. The present invention relates to the textile field, in particular to shape memory polymer fibers, and has been developed in part under the EU project "GrowBot - Towards a new generation of plant-inspired evolving artefacts" (grant agreement no. 824074). [Background technology]

[0002] Shape memory polymers (SMPs) are emerging smart materials that can change size and shape in response to external stimuli, such as heat, electric current, electromagnetic fields, water, and light. Typical SMPs have the ability to remember their original shape after deformation, such as stretching. SMPs maintain their deformed state in the absence of stimuli and return to their original shape upon application of an external stimulus. SMPs are increasingly being investigated for biomedical applications. From a structural perspective, SMPs can be classified into three-dimensional systems, such as shape memory blocks or shape memory foams, two-dimensional systems, such as shape memory films, and one-dimensional systems, such as shape memory fibers, with shape memory fibers receiving the most attention. Shape memory fibers, in woven, nonwoven, and knitted forms, can be transformed into two-dimensional and / or three-dimensional systems.

[0003] Fibrous SMPs have attracted considerable interest in structural and functional applications due to their flexibility, anisotropy, and ability to be transformed into two- and / or three-dimensional systems. Known shape memory fibers are produced by electrospinning from polyurethane block copolymers or multiblock copolymers containing poly(ω-pentadecalactone) hard segments (PPDL) and poly(ε-caprolactone) switching segments (PCL), as disclosed in F. Zhang et al., "Shape Memory Polymer Nanofibers and Their Composites: Electrospinning, Structure, Performance, and Applications," Frontiers in Materials, October 2015, Vol. 2, Article 62, or by extrusion from poly(ethylene-co-vinyl acetate) random copolymers, as disclosed in K. Wang et al., "Thermal and Mechanical Properties of Poly(ethylene-co-vinyl acetate) Random Copolymer (PEVA) and Its Covalently Crosslinked Analogue (cPEVA)," Polymers 2019, 11, p. 1055 (2019).

[0004] Chinese patent application CN1706997A discloses a shape memory fiber made from shape memory polyurethane and a manufacturing method thereof, and Chinese utility model application CN201553838U discloses a heat-sensitive shape memory polyurethane coated yarn (shape memory polymer fiber, cSMPF) and a manufacturing method thereof. Related to this disclosure, Chinese utility model application CN201545991U discloses a central shape memory yarn coated with outer wrapping yarns that are coated on the surface of the central yarn, resulting in a soft hand feel and wrinkle resistance.

[0005] The cSMPF can be programmed by stretching at various temperatures before or after covering with conventional yarns in the textile industry, such as cotton, nylon, and polyester. Compared with other fiber covered yarn structures, the heat-sensitive shape memory polyurethane disclosed herein has better elasticity, stronger fabric wrinkle resistance, and easily recovers to its original permanent shape.

[0006] This coating is not only necessary to overcome technical constraints associated with processing, but may also be necessary for comfort and regulatory requirements to avoid direct contact of such fibers with the wearer's body. The heat-sensitive shape-memory polyurethanes disclosed in CN201553838U are said to improve the wrinkle resistance and elasticity of fabrics compared to other fiber covered yarn structures. The diameter ratio of the covered yarn to the core yarn is reported to be in the range of 0.1 to 1.0.

[0007] WO2012 / 045427A1 discloses medical aids, in particular body support bandages and braces, which comprise at least one element that generates or provides support, compression, or pressure induction and which include or consist of a shape memory material. The programmed shape memory transition of the medical aid is triggered by body heat, whereby the extended shape of the medical aid, which facilitates attachment to the body, changes to a contracted shape that conveys the support and / or compression effect of the medical aid. The shape memory material according to this disclosure is a composite material, a mixture, an alloy, or a composite material with different shape memory effects.

[0008] In addition to the related field of shape memory polymer development and application, there are several known disclosures relating to the manufacture and use of coated fibers, which have improved properties compared to uncoated fibers.

[0009] For example, WO2000038531A1 discloses a tubular packaging for use with food products having a circumferential thread comprising an elastic thread having a predetermined elastic limit, below which the thread is elastically extensible and at which the thread is inextensible. This example from the food industry suggests that threads with a defined elastic limit can be used to limit the expansion of a covering for a tubular thread used with food products.

[0010] An example of the elastic limit or breaking point of elastomeric rubber is given in US 1,679,822 A, which shows a spirally wound, short, low-tension coated elastic rubber thread with a coating layered on top of it in different layers, which are used to significantly reduce stretch below the elastic limit and breaking point of the contained fiber.

[0011] WO2004027132A1, which concerns conductive elastic yarns, discloses an example of an elastic core surrounded by several threads, at least one of which is intended to limit the stretchability of the stiffening fiber. The problem of this application is to provide a softer, thinner and stretchable alternative to electrical wires in textile applications, which is therefore processable on a loom.

[0012] There remains a need in the textile industry for products with shape memory properties that are particularly useful for medical applications. In particular, there remains a need for shape memory polymer fibers (SMPF) for textile and / or medical applications that can maintain consistent shape fixity and recovery over multiple shape memory cycles.

[0013] To date, no method or product is known that specifically produces a reproducible shape memory effect with high shape retention and recovery caused by overstretching the fibers involved, which is particularly important for fibers, fabrics, and textiles that have such a distinct shape memory effect. Summary of the Invention [Problem to be solved by the invention]

[0014] The objective of the present invention is to address and overcome a significant shortcoming in the field of shape memory fibers found in the prior art. Conventional shape memory polymer fibers (SMPFs) exhibit excellent shape memory properties, but are limited by their susceptibility to stretching beyond their recoverable shape memory programming range. This limitation often results in a loss of shape memory function, reducing the effectiveness of the fibers and rendering them unusable for their intended applications, particularly in the degradation of important properties such as shape recovery rate and shape recovery fixation. When the fibers are stretched beyond a certain point, their ability to return to their preprogrammed shape is impaired. This shortcoming not only shortens the functional lifespan of these materials, but also limits their usability in applications where the fibers may be subjected to a variety of strains. This situation is common in fields such as medicine, orthopedics, leisure, sports, and other dynamic environments where adaptability and durability are important.

[0015] Therefore, it is an object of the present invention to develop shape memory polymer fibers (SMPF), particularly coated shape memory polymer fibers, that maintain their shape memory capabilities even under strains exceeding the conventional application limit, i.e., the strain at the yield point of the uncoated core fiber. By improving the hyperextension strength of these fibers, the present invention aims to expand the functional range and durability of shape memory materials and to accommodate a wider range of practical applications than has previously been limited by the mechanical degradation of the shape memory properties of conventional fibers. [Means for solving the problem]

[0016] This problem is solved by a coated shape memory polymer fiber (cSMPF) having the features of claim 1. The invention further discloses a method for its production, a shape memory textile comprising it, a shape memory fabric comprising it, and their uses.

[0017] Further advantageous embodiments and further developments are set out in the dependent claims and in the description with reference to the drawings. [Effects of the Invention]

[0018] The coated shape memory polymer fibers of the present invention solve the mechanical problems associated with the shape memory effect of conventional shape memory fibers, such as shape recovery rate, encountered in practical textile applications, particularly functional apparel and garments used in medical, recreational, and technical applications, by coating a shape memory polymer core fiber with a substantially inelastic covering yarn such that the maximum engineering strain of the core fiber is reduced to or below the strain at the yield point of the uncoated core fiber.

[0019] This allows shape memory materials to be applied to textiles and fabrics that need to be processed into garments that can be used in medical, leisure, and technical applications. One of the key advantages of the disclosed cSMPF is its ability to maintain consistent shape fixity and recovery over multiple shape memory cycles, which is crucial for medical applications where precision and reliability are required.

[0020] Furthermore, this design limits the maximum elongation of the core fibers to a predetermined strain, preventing overstretching and potential structural damage. This limitation is particularly advantageous in medical textiles where controlled compression and consistent support are essential for therapeutic efficacy, especially when consistent and reproducible pressure is required for effective treatment.

[0021] The covering yarn not only limits the stretchability of the core fiber, but also adds another layer of protection that helps protect the core fiber from environmental factors and mechanical abrasion, thereby improving the overall durability and longevity of the fiber and the textile products made therefrom. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention. [Figure 2] FIG. 2A shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention in an unstretched state, and FIG. 2B shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention in an stretched state. [Figure 3] FIG. 3A shows a schematic diagram of an exemplary semi-crystalline shape memory polymer cured using radiation, a benzophenone initiator, and a trifunctional cross-linker (FG = functional group, e.g., ethylene group), and FIG. 3B shows a schematic diagram of the curing process of PEVA polymer to PEVA (covalently cross-linked PEVA) with an initiator and cross-linker, showing some of the potential sites for covalent cross-linking according to the present invention. [Figure 4] FIG. 4A shows an example of thermally programming a shape memory textile comprising coated shape memory polymer fibers (cSMPF) in a laboratory environment, and FIG. 4B shows an example of thermally programming a shape memory textile comprising coated polymer shape memory fibers (cSMPF) on a subject's body. DETAILED DESCRIPTION OF THE INVENTION

[0023] <Coated Shape Memory Polymer Fiber (cSMPF)> The present invention relates to a coated shape memory polymer fiber (cSMPF) having a core fiber and a substantially inextensible covering yarn wrapped around the core fiber such that the maximum engineering strain of the core fiber is reduced to or below the strain at the yield point of the uncoated core fiber.

[0024] In the context of the present invention, "having / having" can be used synonymously or interchangeably with the terms "including" or "consisting of" and means that a feature includes or consists of a specified sub-feature.

[0025] In a further preferred embodiment, the present invention provides a method for manufacturing a semiconductor device comprising: a core fiber (10) comprising or consisting of a shape memory polymer (SMP); - a substantially inelastic covered yarn (20); The present invention relates to a coated shape memory polymer fiber (cSMPF) (1) comprising or consisting of: wherein a substantially inelastic covering yarn (20) is wrapped around a core fiber (10) included in the coated shape memory polymer fiber (1) such that the maximum engineering strain of the core fiber (10) is reduced to or below the strain at the yield point of the uncoated core fiber (10).

[0026] In a further preferred embodiment, the present invention comprises at least a core fiber (10) comprising or consisting of a shape memory polymer; a substantially inelastic covering yarn (20) wrapped around the core fiber (10); The coated shape memory polymer fiber (cSMPF) (1) comprises or consists of a core fiber (10) comprising: max ) is the yield strain (ε ) of the uncoated core fiber (10), preferably measured at 25°C. yield ), where the yield strain (ε yield ) is preferably in the range of 10% to 100%, more preferably in the range of 15% to 70%, and most preferably in the range of 20% to 60%. This has the advantage that the cSMPF exhibits consistent shape stability and recovery over multiple shape memory cycles, ensuring a wide stretch range while maintaining shape memory properties. This is very important for a wide range of textile applications where precision and reliability are required.

[0027] In some preferred embodiments, the maximum engineering strain (ε ) of the core fiber (10) included in the coated shape memory polymer fiber (1) is max ) is the yield strain (ε ) of the uncoated core fiber (10), preferably measured at 25°C. yield ), where the yield strain (ε yield) is in a numerical range obtained by combining any two of the following endpoint values: 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 40%, 45%, 50%, 52%, 54%, 56%, 58%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 100%.

[0028] The "core fiber (10)" in the context of the present invention (also referred to as "core shape memory fiber (10)") may be covered by a substantially inelastic covering yarn (20) that comprises or consists of a shape memory polymer and is wrapped around the core fiber (10). In this context, the maximum engineering strain (ε max ) is the maximum engineering strain (ε max ) is equivalent to

[0029] An "uncoated core fiber (10)" in the context of the present invention (sometimes referred to as "core fiber (10)") comprises or consists of a shape memory polymer that does not have a substantially inelastic covering yarn (20) wrapped around the core fiber (10). Thus, the strain at yield (ε yield ) is equivalent to the yield point of the core fiber (10) of the coated shape memory polymer fiber (cSMPF) without the substantially inelastic covering yarn (20).

[0030] A "fiber" in this invention is a single continuous thread of material that is much longer in one axial direction than two other, relatively short, directions.

[0031] A "filament" in the present invention may be either a monofilament, which corresponds to a "fiber" within the meaning of the present invention, or a multifilament containing at least one "fiber" within the meaning of the present invention. A multifilament is a bundle of co-oriented fibers, and in a preferred embodiment is a filament fiber, i.e., a fiber whose length is comparable to that of the multifilament (common examples are rope, cable, synthetic fiber yarn), or in another preferred embodiment is a staple fiber, i.e., a fiber whose length is significantly shorter than the entire multifilament (common examples are cotton yarn, wool yarn).

[0032] In one aspect, the present invention provides a fiber structure comprising a core fiber of a semi-crystalline polymer fiber and a maximum engineering strain (ε max ) is the yield strain of the uncoated core fiber (ε yield and a substantially inelastic covering yarn wound around the core fiber such that the core fiber has a maximum recovery strain (ρ) of 1. The covering yarn is therefore used to limit the stretchability or deformation of the core shape memory fiber during programming and ensure maximum recovery strain. The maximum deformation of a core fiber of a given length (L) and diameter (D) by covering it with a covering yarn can be affected by the entanglement density (ρ), preferably also referred to as the covering density, of the core fiber in its unstretched state, i.e., the number of twists per meter of the covering yarn when the core fiber is in its unstretched state, as well as the length (l) and diameter (d) of the covering yarn, all of which are related to the diameter (D) of the core fiber in its unstretched state.

[0033] When stress is applied to the coated fiber to elongate the fiber, the length (L1) of the core fiber increases but the entanglement density (ρ1) decreases. The strain (ε) of the core fiber is calculated by the following equation:

number

[0034] In the present invention, "stress" and "strain" can be used interchangeably because the deformation of an SMPF is limited to a yield point and / or elastic limit. Within this range, each strain value may correspond to one stress value. This is why each point on the stress-strain curve of an SMPF can be clearly defined by either a stress value or a strain value.

[0035] When the covering yarn is stretched (elongated) around the wrapped core fiber, the pitch (r), i.e., the distance between two loops of twist of the covering yarn around the core fiber, increases from r0 to r1, and the entanglement density (ρ1) decreases. The covering yarn increases the maximum strain (ε max The core fiber is not stretched until it reaches the maximum strain (ε max ), further elongation requires that the covering yarn also be elongated. max ), the force required for further elongation or deformation increases sharply, and beyond this point, the force exerted by the covered yarn on the core fiber increases, potentially crushing and damaging the core fiber and ultimately causing breakage of the covered yarn.

[0036] According to the present invention, the maximum strain (ε max ) is the strain at the yield point of the core fiber (ε yield ) should be selected so as not to exceed the maximum strain (ε max ) does not depend on the material of the covering yarn, but depends only on the diameter (D0) of the shape memory polymer core fiber (cSMPF), the diameter (d) of the covering yarn, and the entanglement density (ρ0), where entanglement density (ρ0) is defined as follows:

number

[0037] According to some preferred embodiments of the present invention, the yield strain of the shape memory polymer core fiber (cSMPF) depends on the material of the core fiber, particularly the shape memory polymer contained in the core fiber, and the diameter (D0) of the core fiber, and is limited by appropriately selecting the diameter (d) and entanglement density (ρ0) of the covering yarn, as well as the material of the covering yarn, but the maximum strain (ε) of the core fiber is determined by the material and diameter of the core fiber. max ) is the strain at the yield point of the core fiber (ε yield ) must be selected so as not to exceed

[0038] The maximum engineering strain (ε max ) is the yield strain of the uncoated core fiber (ε yield The length of the covering yarn required to reduce the thickness of the core fiber depends on the length of the core fiber and is calculated using the following formula:

number

[0039] The covering yarn can be wrapped around the core fiber with either S or Z twist and with either a single or double twist, with a twist density preferably ranging from 750 to 3000 twists per meter.

[0040] The yield point is the point on the stress-strain curve that indicates the limit of elastic behavior. yield ) is the strain (elongation) that a core fiber can withstand without permanent deformation. The yield point is a material characteristic and can be measured according to ISO 527.

[0041] In a particularly preferred embodiment of the present invention, the "yield point" corresponds to the "elastic limit", which is the point on the stress-strain curve that indicates the limit of elastic behavior. Most preferably, the engineering strain (εyield ) is limited to the strain at the elastic limit. In particular, in the context of shape memory polymers comprising the core fibers of the cSMPF of the present invention, the elastic limit can be measured by an appropriate indirect temperature measurement system, preferably an IR camera, e.g., ThermaCam TM This can be measured by thermomechanical analysis using a Phoenix-equipped tensile testing machine, e.g., an MTS 858 testing machine. An exemplary procedure is described in "Experimental and Numerical Investigation of the Yielding Phenomenon in Shape Memory Polymers Subjected to Cyclic Tension at Various Strain Rates" (E.A. Pieczyska, M. Staszczak, K. Kowalczyk-Gajewska, M. Maj, K. Golasinski, S. Golba, H. Tobushi, S. Hayashi, Polymer Testing, Vol. 60, 2017, pp. 333-342, ISSN 0142-9418, https: / / doi.org / 10.1016 / j.polymertesting.2017.04.014). The importance of distinguishing between elastic and plastic deformation regions is crucial to understanding the behavior of materials under stress. The elastic region represents reversible deformation, while the plastic region represents permanent deformation. The yield point is closely related to the elastic limit and is an indicator of the transition from elastic to plastic behavior, indicating the maximum strain that the SMP can withstand without permanent deformation. max ) to the yield point (ε yield ) or elastic limit is important to ensure a high shape recovery rate and mechanical stability of the shape memory effect against strain.

[0042] The elastic limit can be determined by a step cycle test, as described in "Strain Recovery and Stress Relaxation Behavior of Multiblock Copolymer Blends Physically Crosslinked by PLA Stereocomplexation," Izraylit, V., Heuchel, M., Gould, OE, Kratz, K., and Lendlein, A. (2020), Polymer, 209, 122984, https: / / doi.org / 10.1016 / j.polymer.2020.122984. Here, the elastic limit is determined by a step cycle test. The sample was stretched to a specific strain, ε, at a constant extension rate. Then, the stress was released to zero at the same retraction rate. In each subsequent step, the sample was stretched to a higher strain than the previous step. This cycle continued until the sample broke. The recovered strain was calculated as the elastic component of the deformation, ε. e and the remainder is the plastic component of deformation ε p The elastic limit is ε p (σ) at a particular step in a step cycle experiment. p The yield point is the stress value on the stress-strain curve at a deformation ε related to the strain. In the same study, the yield point is defined as the point in the elastic limit region where the curvature of the stress-strain curve is maximum. In practice, it is preferable that the difference between these points is negligible.

[0043] The expression "substantially inelastic" means that the covered yarn is stiffer than the core fiber. This ratio can be quantified by Young's modulus, a mechanical property that measures the compressive stiffness, and in this context, particularly the tensile stiffness, of a solid material when a force is applied longitudinally. In one embodiment of the invention, the covered yarn has a higher Young's modulus than the core fiber. In another embodiment of the invention, the Young's modulus of the covered yarn is at least twice, preferably at least three times, and most preferably at least five times that of the core fiber.

[0044] In another embodiment, the ratio of the core fiber diameter D, the covering yarn diameter d, and the entanglement density ρ is such that during elongation of the cSMPF, the covering yarn 20 begins to elongate and the tangent slope of the stress-strain curve increases sharply, ε onset is defined such that there exists a relationship between the length of the core fiber 10 and the diameter of the core fiber 10. Other parameters required to determine the ratios of D0, d, and ρ0 are the length of the core fiber L, the length of the covering yarn l, the distance r between two loops of twist, also known as pitch, and the number of twists n. L0 defines the length of the core fiber 10 in an unstretched state, and L1 defines the length of the core fiber 10 in an stretched state. D0 defines the diameter of the core fiber 10 in an unstretched state, and D1 defines the diameter of the core fiber 10 in an stretched state. ΔL is the change in length of the core fiber 10, ΔL = L1 - L0. ΔD is the change in diameter of the core fiber 10, ΔD = D1 - D0.

[0045] The engineering strain ε of the core fiber 10 is given by:

number

[0046] The Poisson's ratio ν of the core fiber 10 is:

number

[0047] The formula for the Poisson's ratio ν of the core fiber 10 is:

number

[0048] From the above equation, the following relationship:

number

[0049] Engineering strain ε of the covered yarn l is a function of the engineering strain ε of the core fiber:

number

[0050] where l1 is:

number

[0051] The formula for the length l1 of the covered yarn 20 in the stretched state can be derived as follows: First, the equation for the circumference of the core fiber 10 and the covered yarn 20 is established. Since the covered yarn 20 is helically wound around the core fiber 10, the number of twists n is multiplied by the distance r1 between the two twists in the stretched state and added to the circumference.

number

[0052] For n and D1, use the formula already established above, and r1 2 n 2 Instead of parameter L1 2 is used.

number

[0053] Here, the equation obtained above is applied to L1 to make the equation into a quadratic equation.

number

[0054] For the selected material, ε is limited by the elastic limit, so the extension can be considered elastic. Therefore, no significant structural changes occur at the molecular level. From this, the volume can be assumed to be constant and the Poisson's ratio can be assumed to be = 0.5. From this, the equation:

number

[0055] For l0, the following formula:

number

[0056] ε onset is ε l It is defined as ε such that (ε) is positive.

number

[0057] By selecting D0, d and ρ0 according to the ratio of D0, d and ρ0, the elongation of the core fiber 10 can be avoided, and the engineering strain ε of the covering yarn can be reduced. l (ε) is the maximum engineering strain (ε max ) can be made positive only if

[0058] In this manner, the covering yarn 20 is wrapped around the core fiber 10 and is subjected to a predetermined engineering strain (ε max ), the covered yarn is deformed, and further elongation of the cSMPF results in axial elongation of the covered yarn. The core fiber 10 is stretched to the engineering strain (ε max ) and released, the residual deformation recovers when heated at a temperature between 25°C and the melting point as defined in ISO 11357. This means that a cSMPF including a core fiber 10 recovers to ε=0 when heated at a temperature between 25°C and the melting point as defined in ISO 11357.

[0059] In some embodiments of the inventive coated shape memory polymer fiber disclosed herein, the core fiber (10) is selected from a shape memory polymer (SMP), and the shape memory polymer is preferably a thermally programmable shape memory polymer SMP having a crystalline rigid segment and a switching segment, wherein the thermally programmable shape memory polymer has a programming temperature (T prog ) is 40 to 80°C, more preferably 40 to 70°C.

[0060] In the context of this patent application, differential scanning calorimetry (DSC) is defined as an analytical technique for measuring the thermal properties of shape memory polymers, particularly semi-crystalline shape memory polymers, contained by the coated shape memory polymer fibers (cSMPF) used in the present invention. DSC is useful for measuring the thermal transitions of these materials, such as melting point, glass transition temperature, and crystallization behavior. This information is essential for understanding and optimizing the thermal response behavior of the cSMPF in the proposed compression garments.

[0061] Shape fixity (R f ) and shape recovery (R r ) is the deformation applied during programming (ε m ), the fixed strain in the temporary shape after removing the stress in the programming stage (ε u ), and the recovery strain in the recovery cycle (ε p ) to the following formula:

number

[0062] In some preferred embodiments, the shape recovery of the coated fibers, particularly the coated shape memory polymer fibers, is between 80% and 100%, more preferably between 92.5% and 100%, and particularly preferably between 95% and 100%, allowing for repeated use in the disclosed applications. In the most preferred embodiments, the shape recovery of the coated fibers, particularly the coated shape memory polymer fibers, is greater than 95%, meeting the requirements of the RAL-387 standard for medical compression garments, particularly preferably in the Class 1 range for a pressure range of 2.4 kPa to 2.8 kPa.

[0063] To ensure and evaluate the long-term shape memory ability of these fibers, we conducted approximately 100 shape memory cycle tests. Throughout the 100 cycles, identical results were obtained regarding the shape recovery rate and low shape retention rate. For practical reasons and to shorten the cycle time, the heating and cooling rates were set to 10 °C min -1 The equilibration time was reduced to 1 minute.

[0064] In a preferred embodiment of the coated shape memory polymer fiber of the present invention, the thermal programming process comprises the following steps: a) The coated shape memory polymer fiber is subjected to a predetermined programming strain (ε ) that is lower than the maximum engineering strain at a controlled rate, preferably ≦10 mm / min. prog ) while stretching to a specific programming temperature (T prog an initial programming step including controlled heating to b) an equilibration step, which comprises holding the extension condition for an equilibration time, preferably between 1 and 10 minutes; c) The coated shape memory polymer fiber is subjected to a predetermined programming strain (ε prog a cooling step comprising cooling the mixture under a low temperature (eg, 1000° C.) to a temperature below the crystallization point, preferably ≦35° C., Includes.

[0065] Programming Temperature (T prog) is preferably between 40 and 80°C, more preferably between 40 and 70°C, and is specific to each embodiment of the coated shape memory polymer fiber and depends on the overall shape memory polymer properties such as crystallinity, type of polymer, and degree of crosslinking. prog ) causes the polymer chains to align in the direction of the applied force. In some preferred embodiments, the programming temperature can be within a range obtained by combining any two of the following endpoints: 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 75°C, or 80°C.

[0066] Particularly preferably, in the context of thermally programmable shape memory textiles and / or shape memory fabrics, the programming temperature is in the range of 40°C to 70°C, or a range combining any two of the following endpoints: 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, or 70°C. This allows for customized programming of the textile or fabric of the invention directly to the subject's body, resulting in a better fit without the risk of burning the subject.

[0067] In some embodiments of the coated shape memory polymer fibers (cSMPF) of the present invention and / or shape memory textiles and / or fabrics comprising the same, the temperature range is selected so that programming and / or shape recovery can be performed directly on the body of a subject. Advantageously, this allows the coated shape memory polymer fibers and / or shape memory textiles and / or fabrics comprising the same to be thermally programmed and recovered to the shape of a subject directly, achieving optimal force distribution.

[0068] In some preferred embodiments, the shape memory textile or fabric is programmed to fit the contours of a patient's body. This means that the shape memory textile or fabric is initially configured to fit the patient's specific body shape. After donning and doffing, it can regain its programmed shape. This is particularly useful in medical garments, where a custom fit is essential for therapeutic effectiveness.

[0069] Another embodiment involves programming the permanent shape of a shape memory textile or fabric at elevated temperatures above the typical range of environmental or body temperatures, ensuring that the programmed shape is not inadvertently altered or distorted by everyday activities such as washing or drying. In this case, the patient is not involved in the programming process. Instead, if deformed during use, the garment regains its shape when worn by the patient. Such garments, including cSMPF or shape memory textiles or fabrics, are designed to maintain their therapeutic shape and function despite everyday handling, ensuring consistency and reliability in medical applications.

[0070] A thermally programmable shape memory polymer may also be semi-crystalline, and vice versa. These two terms refer to different but related properties of shape memory polymers and are not mutually exclusive. In a preferred embodiment, the shape memory polymer is a thermally programmable semi-crystalline shape memory polymer.

[0071] In the most preferred embodiment, the shape memory polymer contained in the core fiber of the coated shape memory polymer fiber (cSMPF) is a semi-crystalline shape memory polymer (SSMP) with a crystallinity of 3% to 70% and is thermally programmable and has a programming temperature (T prog) is between 40 and 80°C, representing a thermally programmable semi-crystalline shape memory polymer. This has the technical effect that the crystalline properties, which are preferably controlled by the manufacturing method of the cSMPF according to the present disclosure and which have a significant impact on the programming temperature, strain, and other parameters of the core fiber, can be modified to achieve the desired programming temperature essential for using the cSMPF in garments, shape memory fabrics, and shape memory textiles, particularly those suitable for thermal programming and recovery in a subject's body.

[0072] The nature of the covered yarns ranges from yarns of natural fibers such as cotton, wool, etc. to semi-synthetic or synthetic yarns such as viscose, acrylic, nylon, polyester, etc. In a further preferred embodiment of the covered shape memory polymer fiber according to the present invention, the covered yarn is selected from cotton, wool, silk, linen, viscose, acrylic, nylon, and polyester.

[0073] In another preferred embodiment of the coated shape memory polymer fiber according to the present invention, the covering yarn is wrapped around the core fiber as a single or double twist with twist in the S or Z direction.

[0074] The diameter ratio of the covering yarn to the core fiber is preferably in the range of 1:1 to 1:20. In further disclosed embodiments of the coated shape memory polymer fibers according to the present invention, the diameter ratio of the covering yarn to the core fiber is preferably in the range of 1:1 to 1:20. A smaller diameter ratio ensures adequate coverage and protection of the core fiber by the covering yarn, while a larger diameter ratio improves the flexibility and adaptability of the core fiber within the covering.

[0075] The diameter of the core fiber in the cSMPF is preferably in the range of 50 to 500 μm. In a preferred embodiment of the coated shape memory polymer fiber, the diameter of the core fiber is 50 to 500 μm.

[0076] The covering yarn may be a multifilament yarn or a monofilament yarn. However, a monofilament yarn is preferred. In a preferred embodiment of the covered shape memory polymer fiber, the covering yarn is a monofilament yarn.

[0077] In a preferred embodiment, the core fiber (10) is a multifilament fiber, preferably with a linear fiber density of 15 to 1000 dtex, more preferably 35 to 600 dtex. Multifilament fibers are composed of many thin individual filaments assembled into a single fiber. This structure may have several advantages, including increased flexibility, increased strength, and improved fracture resistance. In a preferred embodiment, the linear fiber density of the core fiber of the cSMPF is within a numerical range obtained by combining any two of the following endpoint values: 15 dtex, 20 dtex, 25 dtex, 30 dtex, 35 dtex, 40 dtex, 45 dtex, 50 dtex, 75 dtex, 100 dtex, 150 dtex, 200 dtex, 250 dtex, 300 dtex, 350 dtex, 400 dtex, 450 dtex, 500 dtex, 550 dtex, 600 dtex, 650 dtex, 700 dtex, 750 dtex, 800 dtex, 850 dtex, 900 dtex, 950 dtex, and 1000 dtex.

[0078] In a preferred embodiment of the shape memory fabric, the core fiber included in the cSMPF is a multifilament fiber having a linear fiber density of 15 to 75 dtex, more preferably 20 to 50 dtex. Due to the high density of the cSMPF in the shape memory fabric of the present invention, the linear fiber density of the included cSMPF is selected from this range, as a higher linear fiber density results in a stiffer fabric for the applications disclosed herein.

[0079] In another preferred embodiment of the shape memory textile, the core fiber contained in the cSMPF contained in the shape memory textile is a multifilament fiber having a linear fiber density of 250 to 750 dtex, more preferably 300 to 600 dtex. Because the amount of cSMPF fiber in the shape memory textile according to the present invention is small, the linear fiber density of the contained cSMPF is selected from this range, because a lower linear fiber density weakens the shape memory effect.

[0080] In the context of fibers, "dtex" stands for "decitex," a unit of measurement used to describe the linear density or fineness of a fiber. It is defined as the mass in grams per 10,000 meters of fiber.

[0081] In the coated shape memory polymer fiber according to any one of the preceding claims, the covering yarn (20) is wound around the core fiber (10) at a rate of 500 to 6000 turns per meter, preferably 750 to 3000 turns per meter. A higher twist rate ensures that the covering yarn is wrapped around the core fiber, providing stability and protection. At the same time, maintaining a twist rate within this range prevents excessive contraction of the core fiber, which would otherwise interfere with the shape memory function.

[0082] The coated shape memory polymer fibers according to any one of the preceding claims have an elasticity of 30 to 1000%, preferably 50 to 900%. This flexibility in elasticity means that the fibers can meet various functional needs in applications requiring moderate or high elongation. For example, sports and leisure textiles may require high elasticity, while medical or technical applications may be more suitable for moderate elasticity.

[0083] In a preferred embodiment of the coated shape memory polymer fiber (cSMPF), the breaking elongation (ε break) is in the range of 500±150% to 1150±150%, preferably 600±150% to 1000±150%, including the margin of error, which provides a large margin of safety after stretching the fiber beyond the intended engineering strain according to the present invention.

[0084] <Materials and Shape Memory Polymers> The "shape memory polymer" according to the present invention is preferably a semi-crystalline polymer having a rigid segment and a switching segment. The rigid segment, also called the hard segment, is the portion of the shape memory polymer that defines the permanent shape of the material by establishing intermolecular interactions. This segment allows the polymer to retain its original shape information under various conditions and / or after deformation. The rigid segment may be formed by covalent bonds, molecular entanglements, crystallites, or other molecular interactions. The switching segment of the shape memory polymer is responsible for the shape memory behavior of the material. This segment is designed to respond to an external stimulus, such as a temperature change. Upon exposure to a specific temperature associated with a phase transition, also called the programming temperature, preferably the glass transition temperature and / or melting point, the switching segment becomes flexible, and the shape memory polymer becomes flexible at the programming temperature (T prog ) and constant programming distortion (ε prog After applying a stimulus, the material can temporarily change shape after a specified equilibration time. When the stimulus is removed, the segments return to their original state, controlled by the rigid segments, and the material returns to the predetermined shape. The switching segments can be formed by microcrystals, glassy amorphous segments, or other reversible molecular interactions.

[0085] In a preferred embodiment of the coated shape memory polymer fibers of the present invention, the shape memory polymer (SMP) is a semi-crystalline shape memory polymer (SSMP) having a crystallinity of 3% to 70%, more preferably 5% to 60%, as determined by wide-angle X-ray scattering (WAXS), also known as X-ray diffraction spectroscopy (XRD). Alternatively, and preferably, the crystallinity can be determined by DSC. Crystallinity is a property that significantly influences the performance and applications of the shape memory polymer fibers of the present invention. Specifically, for the semi-crystalline shape memory polymers (SSMPs) used in the core of these fibers, crystallinity is directly related to the shape memory and mechanical properties. Importantly, crystallinity influences the phase transition temperature associated with programming the coated shape memory polymer fibers. Preferably, the semi-crystalline shape memory polymer is thermally programmable using crystallinity, more specifically, the content of switching segments in the shape memory polymer, as an indicator of molecular structure, which influences the phase transition temperature and shape fixity associated with thermal programming of the shape memory polymer, as well as its shape memory performance.

[0086] "Crystallinity" in this invention is defined as the fraction of the polymer structure in the core fiber that is in the crystalline state. This crystalline state is characterized by an ordered, closely packed molecular arrangement, as opposed to the less ordered structure of the amorphous regions. Crystallinity influences important properties of SMPs, such as thermal response, mechanical strength, flexibility, and the effectiveness of the shape memory effect.

[0087] For the semi-crystalline shape memory polymers (SSMPs) disclosed herein, the degree of crystallinity can be determined quantitatively and is typically expressed as a percentage, which indicates the ratio of the crystalline portion to the total volume of the polymer, which includes both crystalline and amorphous regions. The present invention is particularly focused on polymers having a crystallinity of 3% to 70%, more preferably 3% to 60%, and most preferably 3% to 50%, and may have a crystallinity range obtained by combining any two of the following endpoints: 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39%, 41%, 43%, 45%, 47%, 49%, 51%, 53%, 55%, 57%, 59%, 61%, 63%, 65%, 67%, 69%, or 70%. This particular crystallinity range is important for achieving a desired balance of material properties, such as stiffness, flexibility, and phase transition temperature, to ensure optimal shape memory function and mechanical performance in various applications.

[0088] In the present invention, wide-angle X-ray scattering (WAXS) is used to accurately determine crystallinity. This technique involves analyzing the diffraction pattern obtained from the polymer and distinguishing between crystalline and amorphous regions. Such accurate determination of crystallinity is essential to ensure that the coated shape memory polymer fibers meet the specific requirements and standards necessary for their intended applications, such as textiles, medical devices, or other technical applications where shape memory and mechanical properties are important. Such measurements can be performed using a Bruker D8 Discover X-ray diffraction system equipped with a two-dimensional detector from Bruker AXS (Karlsruhe, Germany) and a suitable X-ray generator, for example, generating copper K-alpha radiation at a wavelength of 0.154 nm and operating at a voltage of 40 kV and a current of 40 mA. The beam focusing and geometrical characteristics can be adjusted using standard state-of-the-art tools and methods, for example, a graphite monochromator and a pinhole collimator with a 0.8 mm aperture. The sample should be irradiated for an appropriate time, e.g., 60 seconds in transmission geometry, and diffraction images can be recorded with a sample-to-detector distance of 15 cm. Measurements can be performed at room temperature, and diffraction images can be acquired at scattering angles from 8 to 42°C. Two-dimensional diffraction images can be integrated to obtain plots of intensity versus diffraction angle. These profiles can be analyzed using appropriate software known to those skilled in the art, e.g., Bruker's TOPAS software, to determine the degree of crystallinity (DOC), which is the ratio of the area of ​​the crystalline peak to the total area under the diffraction curve (the sum of the area of ​​the crystalline peak and the area of ​​the amorphous halo).

[0089] In a preferred embodiment, the semi-crystalline shape memory polymer (SSMP) comprises or is selected from the list consisting of semi-crystalline polyesters such as polycaprolactone, ethylene-co-monomer polymers such as poly[ethylene-co-vinyl acetate] (PEVA), poly(ethylene-1-octene), poly[ethylene-co-ethyl acrylate-co-maleic anhydride] (PEEAMA), poly[ethylene-co-(methyl acrylate)-co-(glycidyl methacrylate)] (PEMAGMA), di- or multi-block copolymers such as amorphous multi-block alicyclic polyether urethanes (PEU) consisting of poly(tetramethylene glycol) (PTMEG), 1,4-butanediol (1,4-BD) and methylenebis(p-cyclohexyl isocyanate) (H12MDI), or semi-crystalline ionomers such as perfluorosulfonic acid ionomers (PFSA). Although these shape memory polymers have been shown to be thermally programmable shape memory polymers with different programming temperatures and chemistries, they are known to exhibit a degradation effect in shape memory properties with strain beyond the maximum engineering strain, and therefore often do not recover even after multiple cycles or may be irreversibly damaged during programming. Thus, it is the inventors' discovery that combining the semi-crystalline shape memory polymers disclosed herein with substantially inelastic yarns results in coated shape memory polymer fibers that are mechanically robust over multiple thermal programming and recovery cycles.

[0090] Preferably, the semi-crystalline core fiber is selected from a shape memory polymer selected from the group of polycaprolactone, poly[ethylene-co-vinyl acetate] (PEVA), poly(ethylene-1-octene), trans-polyoctenamer-containing polycyclooctene (PCO / TOR), poly[ethylene-co-ethyl acrylate-co-maleic anhydride] (PEEAMA), poly[ethylene-co-(methyl acrylate)-co-(glycidyl methacrylate)] (PEMAGMA), perfluorosulfonic acid ionomer (PFSA), and an amorphous multiblock alicyclic polyether urethane (PEU) consisting of poly(tetramethylene glycol) (PTMEG), 1,4-butanediol (1,4-BD), and methylenebis(p-cyclohexyl isocyanate) (H12MDI); most preferably, the semi-crystalline core fiber is a poly[ethylene-co-vinyl acetate] (PEVA) polymer.

[0091] Furthermore, in a preferred embodiment of the coated shape memory polymer fiber, the core fiber is selected from a shape memory polymer selected from the group consisting of polycaprolactone, poly[ethylene-co-vinyl acetate] (PEVA), poly(ethylene-1-octene), trans-polyoctenamer-containing polycyclooctene (PCO / TOR), poly[ethylene-co-ethyl acrylate-co-maleic anhydride] (PEEAMA), poly[ethylene-co-(methyl acrylate)-co-(glycidyl methacrylate)] (PEMAGMA), perfluorosulfonic acid ionomer (PFSA), and amorphous multiblock alicyclic polyether urethane (PEU) consisting of poly(tetramethylene glycol) (PTMEG), 1,4-butanediol (1,4-BD), and methylenebis(p-cyclohexyl isocyanate) (H12MDI).

[0092] In a particularly preferred embodiment of the coated shape memory polymer fiber according to the present invention, the shape memory polymer comprises poly[ethylene-co-vinyl acetate] (PEVA), where the poly[ethylene-co-vinyl acetate] is formed from poly[ethylene-co-vinyl acetate] polymer (PEVAP), preferably including a cross-linker and / or initiator, for example, preferably by curing under UV, beta or gamma radiation.

[0093] In a preferred embodiment of the present invention, the shape memory polymer fibers may be "crosslinked shape memory polymer fibers." These fibers are characterized by an improved structural integrity and shape memory properties due to the crosslinking process. Crosslinking within the polymer structure of the fibers is achieved by incorporating a suitable crosslinking agent, as previously described, which reacts with the polymer chains to form stable crosslinks. The crosslinked shape memory polymer fibers may preferably be covalently crosslinked polymer fibers.

[0094] Crosslinked shape memory polymer fibers can exhibit superior mechanical strength and shape recovery compared to non-crosslinked fibers. This is because the crosslinks act as junctions within the polymer matrix, affecting the rearrangement process and crystallinity of the bulk material. The degree of crosslinking is carefully controlled to balance flexibility and stiffness, ensuring that the fibers recover to their original shape after being deformed into a temporary shape when exposed to a specific stimulus, typically a temperature change.

[0095] "Poly[ethylene-co-vinyl acetate] (PEVA), also referred to as covalently crosslinked poly[ethylene-co-vinyl acetate] (cPEVA), for the purposes of the present invention, is a copolymer of vinyl acetate and ethylene, starting with a poly[ethylene-co-vinyl acetate] polymer (PEVAP) and crosslinked by chemical means to form new covalent bonds. Crosslinking can be induced by a crosslinker or crosslinking agent. Advantageously, in some embodiments, PEVA can be prepared by mixing different poly[ethylene-co-vinyl acetate] polymers, e.g., PEVAPs with different vinyl acetate contents, with a crosslinking agent and / or initiator and / or by curing, resulting in crosslinking.

[0096] In another preferred embodiment of the coated shape memory polymer fiber of the present invention, the vinyl acetate content of the poly[ethylene-co-vinyl acetate] polymer is 5% to 50% of the total weight of the polymer. In a preferred embodiment of the present invention, the vinyl acetate content of the poly[ethylene-co-vinyl acetate] polymer is 3% to 45% by weight of the total weight of the polymer, or preferably, the crystallinity range may be any two of the following endpoint values: 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39%, 41%, 43%, or 45%. This is because the VA content significantly affects the properties of PEVA, such as flexibility, thermal behavior, and shape memory properties. An increase in VA content is associated with a decrease in crystallinity.

[0097] The vinyl acetate content (VA-content) of PEVA and PEVAP in the present invention can be preferably determined by differential thermogravimetry (DTG) analysis. Two decomposition stages associated with the formation of volatile products are observed in PEVA and PEVAP. The first peak in the DTG curve occurs in the temperature range of 300 to 410°C, which may be due to the deacetylation of VA segments, while at higher temperatures around 420 to 510°C, a second peak indicating the decomposition of residues occurs, which is caused by the cleavage of C-C bonds along the main chain. Therefore, the composition of cPEVA can be calculated based on the weight loss of acetate groups as follows:

number

[0098] In a preferred embodiment of the coated shape memory polymer fiber according to the present invention, the poly[ethylene-co-vinyl acetate] polymer (PEVAP) comprises a cross-linker and / or an initiator. The construction in this context is preferably achieved by mixing one, preferably at least two, poly[ethylene-co-vinyl acetate] polymers with different vinyl acetate contents with a cross-linker, preferably TAIC, and an initiator, preferably BP, followed by initiating cross-linking by irradiation (curing) to obtain PEVA, preferably covalently cross-linked PEVA.

[0099] An exemplary method for performing DSC measurements applicable to the present invention is outlined below. DSC measurements were performed using a DSC 204 Phoenix (NETZSCH, Selb, Germany). This included a comprehensive heating-cooling-heating cycle to accurately characterize the thermal properties of the PEVAP and PEVA shape memory polymers of the present invention. The procedure began with an initial heating process, ramping from room temperature to 200°C at a heating rate of 20°C per minute. This step was crucial in determining the behavior of the material upon heating. After reaching 200°C, the sample underwent a cooling phase to -100°C. This cooling was performed at various rates, including 100°C / min, 50°C / min, 20°C / min, 10°C / min, 5°C / min, and 1°C / min. These various rates were used to accurately determine the temperature at which crystallization of the material occurs, which is an important factor for understanding the thermal behavior and stability of the material.

[0100] Following the cooling step, a second heating experiment was performed, in which the samples were heated from -100°C to 200°C. During this second heating run, the critical thermal transition temperatures of the PEVAP and PEVA shape memory polymers, specifically the melting point and glass transition temperature, were accurately measured.

[0101] Furthermore, the crystallinity index (χc) of the PE segment of PEVAP and PEVA shape memory polymers can be calculated from the heat release curve obtained during DSC analysis. The crystallinity index is an important parameter that indicates the degree of crystallinity within the polymer structure, which affects the mechanical and thermal properties of the material. The calculation is carried out using the following formula:

number

[0102] [Table 1]

[0103] In some preferred embodiments of the coated shape memory polymer fibers according to the present invention, the amount of crosslinker and initiator in the poly[ethylene-co-vinyl acetate] polymer ranges from 0.5% to 5.0% by weight.

[0104] In another preferred embodiment of the coated shape memory polymer fibers according to the present invention, the cross-linker is triallyl isocyanurate (TAIC).

[0105] In some more preferred embodiments of the coated shape memory polymer fibers according to the present invention, the amount of crosslinker and initiator in the poly[ethylene-co-vinyl acetate] polymer ranges from 1.0% to 2.0% by weight.

[0106] In a preferred embodiment of the coated shape memory polymer fiber according to the present invention, the cross-linking agent is benzophenone (BP).

[0107] In one embodiment of the present invention, the polymers are optionally present as a blend, with the content of each polymer in the blend being at least 10 wt%.

[0108] In some preferred embodiments, the content of each shape memory polymer in the blend is at the following endpoint values: 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, 15 wt%, 17 wt%, 19 wt%, 21 wt%, 23 wt%, 25 wt%, 27 wt%, 29 wt%, 31 wt%, 33 wt%, 35 wt%, 37 wt%, 39 wt%, 41 wt%, 43 wt%, 45 wt%, 47 wt%, 49 wt%, 51 wt%, 53 wt%, 55 wt%, 57 wt%, 59 wt%, 61 wt%, 63 wt%, 65 wt%, 67 wt%, 69 wt%. It can be a range obtained by combining any two of 71 wt%, 73 wt%, 75 wt%, 77 wt%, 79 wt%, 81 wt%, 83 wt%, 85 wt%, 87 wt%, 89 wt%, 91 wt%, 93 wt%, 95 wt%, 97 wt%, or 99 wt%, with the total content of all polymers in the blend totaling 100 wt%.

[0109] In another embodiment, the hard segment content, such as (H12MDI) / (1,4-BD), polyethylene-co-monomer content, and trans double bond content in the polymer can preferably vary between 40% and 95%. In some preferred embodiments, the hard segment content in 1,4-butanediol (1,4-BD) and methylene bis(p-cyclohexyl isocyanate) (H12MDI), trans-1,4-butadiene monomer block content in the polymer can preferably vary between 1 and 50 mol%.

[0110] The vinyl acetate content in the poly[ethylene-co-vinyl acetate] polymer can preferably vary from 5% to 50% of the total polymer weight. In one embodiment of the present invention, the poly[ethylene-co-vinyl acetate] polymer (PEVAP) includes a cross-linker such as triallyl isocyanurate (TAIC) and / or an initiator such as benzophenone (BP). Preferably, the amount of cross-linker and initiator in the poly[ethylene-co-vinyl acetate] polymer is 0.5% to 5.0% by weight, for example, in the range of 1.0% to 2.0% by weight.

[0111] In this disclosure, the terms "cross-linker," "crosslinker," and "crosslinking agent" are synonymous and refer to compounds used to establish crosslinks within a polymer matrix. These agents are characterized by having at least two reactive functional groups, which are essential for forming crosslinks, such as covalent bonds, between separate polymer chains and / or between different segments of the same polymer chain. In another mechanism, certain cross-linkers act by forming reactive sites directly on the polymer chains. These sites then react with each other, facilitating crosslinking. This type of crosslinking typically involves the use of strong acids or peroxides.

[0112] The proportion of cross-linker relative to the total weight of the polymer is an important factor, as it has a significant impact on the degree of cross-linking. The proportion of cross-linker relative to the total weight of the shape memory polymer or its precursor before the cross-linking process is preferably in the range of 0.05 wt% to 5 wt%. More specifically, the optimal range for improving the effectiveness and balance of properties of the resulting polymer is 0.1 wt% to 2.5 wt%. This proportion is crucial in influencing the final properties of the shape memory polymer, especially the cross-linking density, mechanical strength, and thermal response.

[0113] In shape memory polymers, the level of crosslinking, also known as the "degree of crosslinking," is particularly important. Higher crosslinking grades tend to decrease the crystallinity, especially the crystallinity, within the polymer. This relationship is crucial in the design of shape memory polymers. The degree of crystallinity directly affects the transition temperature of these semi-crystalline polymers and is an important factor in tailoring the thermal response behavior to meet the specific requirements of the present invention. Therefore, careful consideration must be given to the selection and concentration of crosslinkers to achieve the desired balance between the degree of crosslinking and the degree of crystallinity, enabling the shape memory polymer to perform optimally in its intended application.

[0114] In the case of ethylene-co-monomer polymers or di- or multi-block copolymers containing at least one polyethylene and / or polyalkene polymer block, the cross-linker is preferably a substance having at least two, more preferably two to four, alkene functional groups, preferably allyl or vinyl groups. These cross-linkers can react with radicals generated on the polymer, preferably a shape memory polymer in the sense of the present invention, by irradiation and / or an initiator, preferably a photoinitiator such as benzophenone (BP). This has the advantage that no functional groups are required for this cross-linking, although some functional groups, such as acetate groups, are capable of radical cross-linking. The degree of cross-linking can be influenced by the irradiation time and / or dose and / or the initiator and / or cross-linker concentration, resulting in various parameters suitable for a wide range of shape memory polymers.

[0115] The gel content of a polymer and its crosslinking grade are closely related concepts in polymer chemistry. In certain embodiments of the present invention, the shape memory polymer, preferably a crosslinked shape memory polymer, most preferably a covalently crosslinked shape memory polymer, is characterized by a gel content ranging from 60 to 100%, with a more preferred range being 70 to 100%. This embodiment is particularly important in ensuring the desired physical and mechanical properties of the shape memory polymer for various applications. In some preferred embodiments, the gel content of the shape memory polymer can be a numerical range combining any two of the following endpoint values: 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, 99%, and 100%.

[0116] In this embodiment, the polymers or blends thereof that make up the core fiber can be crosslinked by a variety of mechanisms, including covalent bonds, ionic interactions, or crystallite formation. However, this embodiment focuses on covalently crosslinked polymer networks, which are known for their robustness and stability. According to standards such as ASTM D2765 or ISO 10147, these covalently crosslinked polymers exhibit a gel content of 60 to 100%.

[0117] To measure the gel content (G) of crosslinked core fibers, especially the crosslinked shape memory polymer within these fibers, a solvent extraction method is used. This involves immersing a polymer sample in a solvent such as toluene or xylene at a constant temperature of 110°C or less. The extraction process is carried out for 24 hours, followed by evaporation of the solvent in a vacuum oven set at 45°C for an additional 24 hours. The gel content is calculated using the following formula:

number

[0118] For the purposes of this embodiment, it is important to note that the unextracted fibers are used for coating and various investigations such as thermomechanical analysis and evaluation of shape memory properties.

[0119] This embodiment highlights the relationship between gel content and degree of crosslinking in polymer chemistry. Higher gel content indicates a more extensive crosslinked network, which is essential for achieving the desired shape memory properties. The specific range of gel content mentioned above ensures that the polymer maintains an optimal balance between flexibility and structural integrity, making it ideal for applications requiring precise and reliable shape memory functionality.

[0120] In preferred embodiments of some coated shape memory polymer fibers (cSMPF), the modulus of elasticity (E), also called Young's modulus, is from 1.0±0.5 to 15.0±0.5 MPa, preferably from 2.0±0.5 to 10.0±0.5 MPa, preferably measured at 25° C. This allows for a wide range of applications requiring different stresses and strains.

[0121] <Manufacturing method> The present invention further relates to a method for making the coated shape memory polymer fibers disclosed herein, comprising the steps of extruding a core fiber of poly[ethylene-co-vinyl acetate] polymer, optionally with a cross-linker or cross-linking agent, optionally curing the extruded fiber to covalently cross-link it, and wrapping a covering yarn around the core fiber.

[0122] In a preferred embodiment of the method of the present invention, curing is carried out under UV, beta or gamma radiation.

[0123] In another aspect, the present invention relates to a method for producing coated shape memory polymer fibers (cSMPFs). The method comprises the steps of extruding a core fiber of poly[ethylene-co-vinyl acetate] polymer, optionally with a cross-linker or cross-linking agent, optionally curing the extruded fiber for covalent bonding, preferably by irradiation with UV, beta, or gamma radiation, and winding a covering yarn around the core fiber. Alternatively, cross-linking can be achieved by heating to a temperature below the melting point of the particular polymer, as specified in ISO 11357, and the core fiber after extrusion can be elongated up to 10 times compared to the unstretched extruded fiber. This is preferably achieved by drawing the fiber through a cooling bath and winding it onto a bobbin at a predetermined tension or force.

[0124] The present invention further relates to a method for producing a coated shape memory polymer fiber (cSMPF) according to any one of the preceding claims, comprising the following steps: a) extruding a core fiber (10) of a core fiber precursor for a shape memory polymer according to the present invention, preferably with a cross-linker or cross-linking agent, more preferably a poly[ethylene-co-vinyl acetate] polymer, optionally with a cross-linker or cross-linking agent; then b) curing the extruded fibers, preferably under UV, beta or gamma radiation for covalent cross-linking, then c) winding the covering yarn (20) around the core fiber (10) Includes.

[0125] In the present invention, "curing" refers to the process of inducing crosslinks in shape memory polymers, typically with the goal of achieving covalent crosslinks. This process stabilizes the polymer structure and significantly influences its mechanical, thermal, and, most importantly, shape memory properties. In the case of polymers containing ethylene or olefin monomers, as in the present case, curing can involve direct radical crosslinking. This is often achieved using photoinitiators such as peroxides and / or benzophenones as initiators and preferably crosslinkers such as TAIC. Under certain conditions, such as thermal activation or electromagnetic radiation, the initiator decomposes to generate free radicals, which promote the formation of covalent bonds between polymer chains.

[0126] In this first step, a core fiber precursor formulated to be a shape memory polymer is extruded. In some preferred embodiments, the precursor is poly[ethylene-co-vinyl acetate] polymer (PEVAP). Optionally, a cross-linker or cross-linking agent is included in the mixture. The presence of a cross-linker is crucial if improved structural integrity or specific mechanical properties, including shape memory properties, are desired in the final cSMPF.

[0127] Alternatively, curing can be achieved using irradiation methods such as UV, beta, or gamma radiation, in combination with an initiator and, optionally, a cross-linker. In these methods, the extruded polymer is exposed to high-energy radiation, generating free radicals that initiate the cross-linking process. Irradiation provides a controlled method of cross-linking, allowing for precise manipulation of the polymer's properties.

[0128] After curing, the covering yarn is wrapped around the core fiber, this yarn being typically substantially non-stretchable, to provide additional structural support and protection to the core fiber.

[0129] In a preferred embodiment of the present invention, the shape memory polymer precursor is prepared prior to step a) by a comprehensive compounding process, which involves several carefully controlled steps to ensure optimal mixing of the polymer and the reagents, preferably the initiator and the cross-linker.

[0130] In some preferred embodiments, a 50:50 mixture of initiator and cross-linker, preferably BP and TAIC, is prepared. This mixture is then hand-mixed with a shape memory polymer precursor, such as PEVAP (poly[ethylene-co-vinyl acetate]) polymer granules. This hand-mixing ensures preliminary and uniform dispersion.

[0131] The manually mixed materials are then mixed in a twin-screw extruder. The extruder is set to a specific temperature profile: 25°C in the feed zone, gradually increasing to 80°C, then maintaining 110°C throughout the melting and mixing zones, and finally reaching 100°C at the die. The screw rotation speed is preferably 30-60 rpm, more preferably 45-55 rpm. This controlled environment ensures thorough mixing and melting of the ingredients, resulting in a homogeneous mixture.

[0132] After initial extrusion, the continuous filaments can be chopped into granules. This pelletization process converts the extruded blend into manageable granules for easier further processing and handling. Advantageously, the blend can be stored under controlled conditions for further processing.

[0133] In some preferred embodiments, the shape memory polymer precursor may be pelletized and extruded multiple times to obtain a more uniform distribution.

[0134] Preferably, the granules are dried overnight at a temperature of 30 to 80° C., preferably 35 to 55° C. This drying step is important to remove residual moisture that could potentially interfere with the subsequent curing process of the polymer.

[0135] In a preferred embodiment, the uncured shape memory polymer fiber is provided as a monofilament having a diameter of 0.05 mm to 0.5 mm. This diameter range is selected to balance the mechanical strength and flexibility of the fiber. Preferably, the mixture is fed into a single-screw extruder for extrusion. The extruder is equipped with a variable diameter filament die to produce monofilaments of the desired thickness, as disclosed herein. In some embodiments of the extrusion process, the feed zone can be maintained at 20°C to prevent premature melting of the mixture. The temperature can then be increased to 80°C, followed by maintaining a constant temperature of 110°C throughout the melt zone. Finally, the die temperature is set to 100°C. This controlled temperature profile is important for achieving uniform melting and smooth flow of the polymer through the die. The screw rotation speed during extrusion is maintained between 5 and 20 rpm. This rotation speed range allows for careful control of the extrusion process, ensuring that the monofilament is extruded at a constant speed and with a uniform diameter.

[0136] In another preferred embodiment, the shape memory polymer fibers before curing are provided as multifilaments with a linear density of 40 to 500 dtex. This can be achieved by melt spinning, a process similar to extrusion, except that a spinneret is used at the end. The spinneret preferably contains 20 to 200, more preferably 36 to 150, holes through which multiple filaments are extruded. Preferably, the filaments are extruded simultaneously and collected as a single continuous filament. This process can produce bundles of filaments that can be used in a variety of textile applications.

[0137] In some preferred embodiments, the shape memory polymer fibers are cured by in-line UV irradiation integrated into the fiber extrusion process. This method allows for immediate crosslinking of the fibers during production, streamlining the manufacturing process. Alternatively, crosslinking can be performed as a post-treatment step. This can be done by UV irradiation or electron beam irradiation.

[0138] The electron beam irradiation can be carried out at different doses, preferably 50 to 200 kGy, particularly preferably 90 to 170 kGy, to achieve different degrees of crosslinking depending on the specific requirements of the application. This type of irradiation is particularly effective in achieving high degrees of crosslinking by inducing free radicals in the polymer, which is advantageous for applications requiring robust shape memory properties.

[0139] <Shape memory textiles and fabrics> In a further embodiment, the present invention relates to a shape memory fabric comprising or consisting of a coated shape memory polymer fiber (cSMPF) comprising a core fiber (10) according to the present invention and a substantially inelastic covering yarn (20), wherein the coated shape memory polymer fiber (cSMPF) a) a shape memory mesh network in which cSMPFs are interwoven or intertwined, preferably by techniques such as knitting, weaving, crocheting, braiding, etc., to form an operatively linked structure; and / or b) a shape memory inlay disposed in a second fabric, preferably a non-shape memory fabric; placed in Here, the maximum engineering strain of the core fiber (10) is reduced to below the strain at the yield point of the uncoated core fiber (10), which has the advantage that the robust shape memory effect of the cSMPF, as disclosed herein, is coordinated with the surrounding fibers, so that the entire textile exhibits the desired shape memory properties uniformly.

[0140] "Non-shape memory fabric" refers to a fabric that does not contain or is not composed of coated shape memory polymer fibers (cSMPF) according to the present invention. Typical fabrics are known to those skilled in the art. Preferably, the further and / or second fabric is a non-shape memory fabric. This allows the integration of well-defined fabrics known in the art, to which the shape memory effect of the cSMPF according to the present invention can be added.

[0141] The term "interwoven" for purposes of the present invention refers to a method of arranging coated shape memory polymer fibers (cSMPF) by regularly crossing them over and under one another. For example, as defined in ISO 3572:1976, this weaving process forms a fabric or mesh network in which the cSMPF cross at regular intervals to form a grid-like structure. In an interwoven design, the cSMPF can be arranged perpendicularly or at other angles to create a variety of weave patterns. Interwoven cSMPF ensures that the shape memory effect is evenly distributed throughout the fabric, ensuring consistent performance and functionality.

[0142] Intertwining, on the other hand, is achieved by twisting or intertwining the cSMPF rather than following a regular, over-and-under weaving pattern. This technique results in a more flexible, unstructured fiber arrangement. Intertwined cSMPF creates fabrics in which the fibers are looped or knotted around each other, forming a network that enhances flexibility and adaptability in textile design while maintaining shape-memory properties.

[0143] In both interwoven and intertwined configurations, cSMPFs form functionally connected structures, resembling a mesh network or fabric, with each individual fiber contributing to the overall shape memory function of the textile. Functionally connected means that the movement or deformation of one fiber influences and coordinates the surrounding fibers, allowing the entire textile to uniformly exhibit the desired shape memory properties.

[0144] Those skilled in the art of textile manufacturing will appreciate the various ways in which fibers can be arranged to form such functional interlocking structures. Techniques such as knitting, weaving, braiding, knotting, etc. can be used to form shape memory fabrics. The choice of technique will depend on the desired properties of the final product, such as flexibility, stretch, strength, and the particular shape memory properties desired.

[0145] Additionally, the present invention encompasses the concept of shape memory inlays, which involve embedding or integrating a cSMPF into a second fabric, preferably a non-shape memory fabric. This inlay technique allows for the incorporation of shape memory properties into conventional fabrics, improving functionality without changing their basic properties. This integration can be achieved not only through specific knitting processes, but also through stitching, adhesive bonding, or other methods known to those skilled in the art.

[0146] The present invention further relates to a shape memory textile comprising the coated shape memory polymer fiber (cSMPF) according to the present invention and at least a further fabric, preferably a non-shape memory fabric, and / or further fibers, preferably non-shape memory fibers, wherein the cSMPF is disposed within and / or on the shape memory textile, preferably by knitting, such as circular knitting, flat knitting, or jacquard knitting, weaving, preferably inlay weaving or layer weaving, braiding, embroidery, composite techniques, or 3D textile construction, such that the maximum engineering strain of the core fiber (10) is reduced to or below the strain at the yield point of the uncoated core fiber (10). This maintains the structural integrity and shape memory properties of the cSMPF within the textile and prevents overstretching and potential damage to the fibers.

[0147] In the present invention, knitting is utilized as a preferred method for incorporating coated shape memory polymer fibers (cSMPF) into shape memory textiles. This technique allows for the creation of fabrics with connected loops of yarn, which can be fashioned into various shapes. Circular knitting is a preferred method for producing seamless, tubular structures, knitting in a continuous circular motion. This technique is ideal for the production of socks, tubulars, and other circular garments. Incorporating cSMPF into circular knitting enables innovative applications, such as tubular compression garments with shape memory properties. Flat knitting allows for more complex designs and patterns, as it knits back and forth in rows. Flat knitting is suitable for the production of larger, flatter fabrics that can be cut and sewn into specific garments. The use of cSMPF in flat knitting allows for the creation of shape memory fabrics with complex shapes and intricate designs. Jacquard knitting is a specialized knitting method that allows for the creation of multiple colors and complex patterns. The use of cSMPF in jacquard knitting not only imparts functional shape memory properties but also enhances the aesthetics of the fabric, making it suitable for fashion and design-oriented applications.

[0148] Embroidery, as applied in this invention, is a technique for decoratively stitching coated shape memory polymer fibers (cSMPF) onto a base fabric. This technique allows for precise placement of the cSMPF and allows for the addition of shape memory functionality in specific patterns or designs. Embroidery can be used to create localized areas with shape memory properties, thereby adding functional value, such as adaptive fit or dynamic structural support, to specific areas of a textile, such as in sports and leisure apparel and specialized medical applications, e.g., individualized burn and scar dressings.

[0149] Composite technology refers to combining cSMPF with other materials to form composite textiles. This approach involves layering, bonding, or embedding cSMPF with other fabrics or materials, which can enhance the overall properties of the textile. The result is a synergistic combination that integrates the shape-memory properties of cSMPF with the structural, thermal, or other properties of different materials. Composite technology is particularly useful in applications requiring a balance of flexibility, strength, and adaptive shape-memory functionality.

[0150] Braiding involves intertwining multiple yarns of cSMPF, and possibly other types of fibers, in a regular pattern. This method offers a unique way to produce strong, flexible, and durable textiles with shape memory properties. Braided structures are particularly well suited for applications requiring high tensile strength and recovery, such as medical devices, protective clothing, or structural applications where the shape memory effect can be utilized for dynamic functionality. The braiding process allows for the creation of complex three-dimensional textile structures with enhanced shape memory properties.

[0151] Furthermore, the present invention relates to a method for producing a shape memory textile and / or a shape memory fabric, comprising the following steps: a) providing a coated shape memory polymer fiber (cSMPF), then b) Placing the coated shape memory polymer fibers (cSMPF) into and / or on the textile or fabric, preferably by knitting, particularly preferably by circular knitting, flat knitting, jacquard knitting, weaving, particularly preferably by inlay weaving, overlapping weaving, braiding, embroidery, composite techniques or 3D textile structuring. Includes.

[0152] In summary, this method for manufacturing shape-memory textiles or fabrics is characterized by its versatility and adaptability. By selecting and combining different techniques for deploying cSMPFs, a wide range of textiles and fabrics with customized shape-memory properties can be created. This approach enables the development of innovative products suitable for a variety of applications, from clothing and accessories to medical devices and industrial materials.

[0153] The first step in the supply chain involves the manufacturing or sourcing of cSMPFs, the basic building blocks of shape memory textiles or fabrics. These fibers are characterized by a shape memory polymer core surrounded by a non-stretchable yarn. The composition, thickness, and properties of these fibers are selected based on the desired properties of the final textile or fabric.

[0154] <Use of coated shape memory polymer fibers> Additionally, the use of the coated shape memory polymer fibers described herein in compression garments, orthopedic bandages, braces, posture corrective garments, push-up garments, corsets and corsages, and sports garments is disclosed.

[0155] In another aspect, the present invention relates to the use of coated shape memory polymer fibers (cSMPF), which can be used, for example, in compression garments, orthopedic bandages, braces, posture corrective garments, push-up garments, corsets and corsages, and sports garments.

[0156] One embodiment of the present invention relates to a shape memory polymer fiber (SMPF) for textile applications, particularly for medical applications, in which the shape fixity and recovery properties remain constant over multiple shape memory cycles. The invention relates to a semi-crystalline polymer core fiber and a shape memory fiber having a maximum engineering strain (ε max ) is the yield strain of the uncovered core fiber (ε yield and a substantially non-stretchable covering yarn wrapped around the core fiber such that the stretch or deformation of the core shape memory fiber is reduced to or below 100%. Thus, the covering yarn is used to limit the stretch or deformation of the core shape memory fiber during programming and ensure maximum recovery strain.

[0157] [Table 2]

[0158] Also disclosed by the present invention is the use of the coated shape memory polymer fibers in textiles, preferably shape memory textiles such as technical, medical, orthopedic, industrial, sports or leisure textiles.

[0159] Preferred is the use of coated shape memory polymer fibers in fabrics, preferably shape memory fabrics such as technical, medical, orthopedic, industrial, sports or leisure fabrics.

[0160] Particularly preferred is the use of shape memory textiles or fabrics as medical, orthopedic and / or compression garments, preferably as repetitively thermally programmable medical, orthopedic and / or compression garments by heating to 40-70° C. on the body of a subject, thereby improving comfort and effectiveness without the risk of inflicting burns on the subject's body.

[0161] Also preferred is the use of shape memory textiles or fabrics as sports or leisure garments, preferably as sports or leisure garments that can be repeatedly thermally programmed by heating to between 40 and 70°C on the body of a subject.

[0162] In a preferred embodiment, the shape memory textile and / or fabric is custom tailored for individuals between the ages of 50 and 90. This embodiment is designed to address age-related conditions such as poor circulation, edema, varicose veins, and post-surgical recovery support. The garment features graduated compression to promote blood flow, normalize reflux, reduce swelling, and improve overall comfort, making it suitable for everyday wear and increased mobility for this age group.

[0163] Another embodiment focuses on athletes and sports enthusiasts between the ages of 15 and 50. This version's shape-memory textiles and / or fabrics are designed to support muscle recovery, reduce fatigue, and improve athletic performance. It features materials and designs suitable for high-intensity activities and endurance sports. The garment is optimized for activities such as running, cycling, and team sports, where the need for muscle volume and support is prominent.

[0164] Another embodiment of shape memory fibers and / or fabrics is in compression therapy applications where highly personalized garments and / or bandages are required for individual cases, such as treatment of burns, scars, or ulcers, where the patient's body deformation or prescribed treatment requires a specific fit and / or compression profile.

[0165] Specialized embodiments of shape memory textiles and / or fabrics are designed for pregnant women. The garments are tailored to the changing body during pregnancy, providing support and comfort while managing symptoms such as leg swelling. The design ensures safety and ease of use, making it a practical solution for everyday wear during pregnancy.

[0166] One embodiment of the present invention is specifically tailored for people suffering from lymphatic disorders, such as lymphedema. The shape-memory textile and / or fabric is designed to promote lymphatic circulation and reduce swelling and discomfort associated with lymphatic fluid buildup. Its unique construction is designed to provide targeted support to the affected area. The shape-memory effect and thermally programmable nature allow for a customizable solution.

[0167] Further embodiments address the needs of individuals who have limited mobility and / or particular difficulty donning and doffing compression garments. Shape memory textiles and / or fabrics can simplify this procedure by relying on the shape memory effect, making it easier to don the compression garment and subsequently adjust it to the required fit and compression, and easier to doff the compression garment without significant and irreversible damage to its therapeutic properties.

[0168] Preferred embodiments address the needs of individuals with posture problems or who lead sedentary lifestyles. Shape memory textiles and / or fabrics provide postural support, especially for individuals who sit for long periods of time or who have poor posture due to their occupation. The design focuses on promoting good posture and reducing strain on the back and legs.

[0169] Special embodiments have been developed for long-haul travelers, especially those taking long flights. These shape-memory textiles and / or fabrics are designed to prevent cardiovascular problems, such as deep vein thrombosis (DVT). They have compression properties that promote blood flow in the lower extremities, making them an essential travel accessory for health-conscious travelers.

[0170] Finally, one embodiment is designed for individuals whose occupations require prolonged standing or heavy lifting. The shape memory textiles and / or fabrics of this embodiment can reduce leg fatigue, support muscle endurance, and improve overall comfort during long work hours. This is particularly beneficial for workers in fields where physical demands are a regular part of their work, such as healthcare, construction, and retail.

[0171] The present invention also relates to thermally programmable textiles, such as thermally programmable textiles for technical, medical, orthopedic, industrial, sports, or leisure applications, comprising or consisting of the coated shape memory polymer fibers or shape memory fabrics or shape memory textiles of the present invention, preferably with a compression force of 0.5 to 8.5 kPa. These compression levels are crucial in medical applications, such as improving blood circulation, reducing swelling, and supporting injured or weakened body parts. A further advantageous feature of these garments is their thermal programmability in the range of 40 to 70°C, allowing for easy adjustment of the compression level to suit the subject's body and accommodate different stages of recovery or swelling.

[0172] The present invention discloses the preferred use of thermally programmable textiles as medical or orthopedic garments, preferably with a pressure of 0.5 to 8.5 kPa, and preferably thermally programmable repeatedly by heating on the body of a subject to temperatures of 40 to 70°C.

[0173] Furthermore, the present invention discloses the use of a thermally programmable textile as a sports or leisure garment, preferably with a pressure of 0.5 to 8.5 kPa, and preferably thermally programmable repeatedly by heating to 40 to 70°C on the body of a subject.

[0174] Furthermore, the present invention relates to thermally programmable fabrics, such as shape memory fabrics for technical, medical, orthopedic, industrial, sports or leisure applications, comprising or consisting of coated shape memory polymer fibers, shape memory fabrics or shape memory textiles, preferably with a pressure of 0.5 to 8.5 kPa.

[0175] The present invention discloses the preferred use of thermally programmable fabrics as medical or orthopedic garments, preferably with a pressure of 0.5 to 8.5 kPa, and preferably thermally programmable repeatedly by heating to 40 to 70°C on the body of a subject.

[0176] Furthermore, the present invention discloses the preferred use of the thermally programmable fabric as a sports or leisure garment, preferably with a compression force of 0.5 to 8.5 kPa, and preferably thermally programmable repeatedly by heating to 40 to 70°C on the body of a subject.

[0177] <Definition> In the following description, certain terms and their derivatives are used for convenience and not for purposes of limitation. For example, the terms "top," "upward," "upward," "downward," "below," "downward," "left," and "right" refer to directions in the referenced drawings unless otherwise specified. Similarly, the terms "inward" and "outward" refer to directions toward or away from the geometric center of a device or region, or particular portion thereof. Unless otherwise specified, references in the singular include the plural, and vice versa.

[0178] In this patent application, the term "subject" refers to an individual or group that may benefit from the use of the coated shape memory polymer fibers (cSMPF) disclosed herein and / or shape memory textiles and / or shape memory fabrics comprising same.

[0179] "Programming," particularly "thermal programming" or "thermal programming," refers to a process of reversibly changing the shape of a coated shape memory polymer fiber, including a core fiber that includes or consists of a shape memory polymer. The shape and properties of a shape memory polymer can be changed by rearranging and equilibrating the crystalline rigid segments and switching segments. Thermally programmable shape memory polymers can be programmed by a specific thermal programming process.

[0180] Finally, it should be noted that all features described in the application documents, in particular in the dependent claims, are entitled to independent protection individually or in any combination, notwithstanding any formal reference to one or more specific claims. Further advantages, features and possible applications of the present invention are apparent from the following description of the embodiments and the drawings. All features described and / or shown, individually or in any combination, constitute the subject of the present invention, independently of any claims or abstracts referred to therein. Features described in the claims and in the description may each be essential to the invention, either alone or in any combination.

[0181] Furthermore, those skilled in the art will undoubtedly understand that the individual features described in the above specific embodiments can be combined with each other in any suitable manner unless a contradiction arises, and therefore, in order to avoid unnecessary repetition, individual descriptions of various possible combinations will be omitted. [Example]

[0182] The present invention will be explained in more detail with reference to the following figures and embodiments, but without limitation thereto, and in particular the features shown in the individual figures and described for each embodiment are not limited to the individual embodiments.

[0183] In order to explain the basic principle of the device according to the present invention, an example of an embodiment is shown. Please note that the proportions, dimensions, degree of deformation, or amount of displacement of the components according to the present invention may differ from those in reality for the purpose of explanation.

[0184] Unless the context clearly indicates otherwise, the singular forms also include the plural forms. The above-mentioned features, characteristics, and advantages of the present invention, as well as the manner in which they are achieved, will be more clearly understood in the context of the following description of the embodiments. Where the term "may" is used in this application, it refers to both technical possibility and actual technical implementation.

[0185] The invention will now be explained in more detail with reference to exemplary embodiments accompanied by drawings. FIG. 1 shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention; FIG. 2A shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention in an unstretched state; FIG. 2B shows a schematic diagram of a coated shape memory polymer fiber (cSMPF) according to the present invention in an elongated state. FIG. 3A shows a schematic diagram of an exemplary semi-crystalline shape memory polymer cured using radiation, a benzophenone initiator, and a trifunctional cross-linker (FG=functional group, e.g., ethylene group). FIG. 3B shows a schematic diagram of the curing process of PEVA polymer to PEVA (covalently crosslinked PEVA) with an initiator and crosslinker, showing some of the potential sites for covalent crosslinking according to the present invention. FIG. 4A shows an example of thermally programming a shape memory textile, including coated shape memory polymer fibers (cSMPF), in a laboratory setting. FIG. 4B shows an example of thermally programming a shape memory textile comprising coated polymer shape memory fibers (cSMPF) on the body of a subject.

[0186] Figure 1 shows an exemplary embodiment of a covered shape memory polymer fiber (cSMPF) having a core fiber (10) and a substantially inelastic covering yarn (20) wrapped around the core fiber (10). The covering yarn (20) reduces the maximum engineering strain (ε) of the core fiber (10). max ) is the strain at yield point of the uncoated core fiber (10) (ε yield ) or less.

[0187] The present invention defines a cSMPF structure for the purpose of preventing excessive elongation of the core fiber 10 and preventing irreversible plastic deformation of the core fiber 10, and deterioration of the mechanical properties, shape memory properties, and shape of the core fiber 10.

[0188] Figures 2A and 2B show exemplary embodiments of a coated shape memory polymer fiber in two states. In both states, the coated shape memory polymer fiber has a core fiber 10 and a substantially inelastic covering yarn 20 wrapped around the core fiber 10. In Figure 2A, the core fiber 10 is in an unstretched state. Figure 2B shows the core fiber 10 in an extended state. It can be seen how the coil / twist spacing of the covering yarn 20 changes as the core fiber 10 is mechanically deformed during programming (from Figure 2A to Figure 2B) and recovery (from Figure 2B to Figure 2A). As the core fiber 10 wrapped with the covering yarn 20 is stretched (elongated), the pitch of the covering yarn 20 around the core fiber 10, i.e., the distance between twist loops, increases from r0 to r1, thereby decreasing the entanglement density (ρ1).

[0189] Figure 3A is a schematic diagram of a representative semi-crystalline shape memory polymer, illustrating the radiation-induced curing process. This process uses a photoinitiator and a trifunctional cross-linker, where each functional group (FG), such as an ethylene group, actively participates in the cross-linking reaction. The diagram highlights the molecular structure of the polymer before and after the cross-linking process. It shows how the functional groups of the cross-linker interact with the polymer chains, forming a network structure that imparts shape memory properties to the polymer.

[0190] Figure 3B is a schematic diagram of the curing process that converts PEVA polymer into covalently cross-linked PEVA. The diagram shows the various sites within the PEVA polymer that are susceptible to covalent cross-linking upon exposure to initiators and cross-linkers. The diagram details the structural changes at the molecular level, highlighting the sites where cross-linking occurs, improving the mechanical strength and shape memory properties of the polymer.

[0191] Figures 4A and 4B illustrate the shape memory properties of a shape memory textile according to the present invention, with 4A demonstrating thermal programming in the laboratory and 4B demonstrating the ability to reprogram the fibers on the surface of a subject's body due to the thermal barrier properties of the covering yarn and other fabrics comprising the textile.

[0192] <Design example> The present invention will be explained in more detail with reference to the following figures and example embodiments, without however limiting the invention thereto.

[0193] The following table shows some preferred shape memory polymers that make up the core fiber, and Sample ID Numbers: 1 to 20 show some preferred examples of shape memory polymers of the present invention, but are not limited to these, and each is a separate embodiment of the present invention.

[0194] [Table 3]

[0195] Example 1: Coated shape memory polymer fiber In this example, a cSMPF was fabricated according to the method of the present invention. In the first step, the shape memory polymer of the present invention was prepared by first preparing a core fiber precursor.

[0196] First, a 50:50 mixture of initiator and cross-linker, in this case BP and TAIC, is prepared. This mixture is then hand-mixed with PEVAP (poly[ethylene-co-vinyl acetate]) polymer granules. This hand-mixing ensures preliminary and uniform dispersion of the BP / TAIC mixture and the PEVA granules.

[0197] The manually mixed materials are then mixed in a twin-screw extruder (Euro Prism Lab, Thermo Fisher Scientific, Waltham, USA). The extruder is set to a specific temperature profile: 25°C in the feed zone, then gradually increase to 80°C, then maintain 110°C throughout the melting and mixing zones, and finally reach 100°C at the die. The screw rotation speed is controlled between 30 and 50 rpm, with 50 rpm being preferred. This controlled environment ensures thorough mixing and melting of the components, resulting in a homogeneous mixture.

[0198] After initial extrusion, the continuous filaments are chopped into granules. This pelletizing process reduces the extruded mixture to a manageable granule form for easier subsequent processing and handling.

[0199] The blended granules (PEVAP+BP+TAIC) are then subjected to a second extrusion process. This second extrusion process uses the same temperature profile and screw rotation speed as the first process, ensuring consistent and thorough mixing. This repeated extrusion process is essential to achieve uniform dispersion of the crosslinker within the polymer matrix. As with the first extrusion process, the extruded blend is again pelletized into granules after the second extrusion process.

[0200] Finally, the granules are dried overnight at a temperature of 40° C. This drying step is essential to remove any residual moisture that may adversely affect the subsequent curing process of the polymer.

[0201] The compounded mixture is then fed and extruded into a single-screw extruder (Extrudex, Mühl-Acker, Germany) equipped with filament dies of various diameters to produce monofilaments of the desired thickness.

[0202] The monofilaments are extruded in diameters between 0.05 mm and 0.5 mm, a diameter range chosen to balance the mechanical strength and flexibility of the fiber.

[0203] The feed zone is maintained at 20°C to prevent premature melting of the mixture. The temperature is then increased to 80°C, and a constant temperature of 110°C is maintained throughout the melt zone. Finally, the die temperature is set at 100°C. This temperature control profile is critical to achieving uniform melting and smooth flow of the polymer through the die.

[0204] The screw rotation speed during extrusion is maintained between 5 and 20 rpm. This rotation speed range allows careful control over the extrusion process and ensures that the monofilament is extruded at a constant speed and with a uniform diameter.

[0205] The polymers contained in the core fiber or its blend can be crosslinked by covalent bonds, ionic interactions, or crystallites.

[0206] The shape memory polymer fibers were cured by in-line UV irradiation integrated with the fiber extrusion process, which allows for instant crosslinking while the fibers are being produced, streamlining the manufacturing process.

[0207] The gel content of the covalently cross-linked polymer network is between 60 and 100% according to ASTM D2765 or ISO 10147. The gel content (G) of the cross-linked core fiber, more specifically the cross-linked shape memory polymer comprised by the core fiber, was evaluated by extraction with a solvent such as toluene or xylene at a constant temperature of ≦110°C. The extraction time was 24 hours, followed by evaporation of the solvent in a vacuum oven at 45°C for 24 hours. G is the isolated weight of the sample, m iso and the dry weight after extraction m d It was calculated using the following formula:

number

[0208] However, unextracted fibers were used for coating and for investigating thermomechanical and shape memory properties, etc. Table 3 shows the gel content measurements for various exemplary shape memory polymers consistent with the present invention.

[0209] In this particular embodiment, the shape memory polymer selected to comprise the core fiber (10) was PEVA. Semi-crystalline cross-linked poly[ethylene-co-vinyl acetate] (cPEVA) fibers were single- or double-wrapped with a yarn twist of 750 to 3000 turns per meter. The twist count was chosen to maximize the maximum engineering strain (ε) of the core shape memory polymer fiber while allowing for some deformation. max ) is the strain at yield point of the uncoated core fiber (ε yield ) or less.

[0210] The effects of the twist density and twist angle of the covered yarn on the stretchability during programming and recovery of SMP covered yarn were evaluated.

[0211] In this exemplary embodiment, the mechanical properties of the coated and uncoated shape memory polymer fibers were tested by tensile tests at room temperature and at elevated temperatures (up to and within a wide melting transition temperature range). These tensile tests were performed at a strain rate of 5 mm min using a Zwick / Roell testing machine Z005 (Zwick, Ulm, Germany) equipped with a thermochamber and temperature controller (Eurotherm Regler, Limburg, Germany). -1 The temperatures selected for the measurements were 25°C, 37°C, 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C.

[0212] Several properties were measured for exemplary coated shape memory polymer fibers (cSMPF) SMP-1 to SMP-8, SMP-10, SMP-17 to SMP-20 (Table 3) according to this particular embodiment. The modulus of elasticity (E) (at 25°C) ranged from 2.49±0.1 to 9.07±0.3 MPa, and the elongation at break (ε break ) and stress at break (σ break ) was obtained and analyzed. break The range of strain at yield (ε ) was measured to be 730±130% to 915±20%. The shape recovery (after normal elongation to 50%) in these particular examples was measured to be 97% to 100%. yield ) was determined to range from 24±0.2% to 54±0.5%.

[0213] Similarly, the shape memory properties of the fibers were evaluated in a Zwick / Roell machine Z005 (Zwick, Ulm, Germany) equipped with a thermochamber and temperature controller (Eurotherm Regler, Limburg, Germany). Each shape memory cycle in one experiment consisted of an initial programming step followed by heating and cooling rates of ≤10 °C min -1 Each shape memory test consisted of at least three cycles. A single-step programming procedure was applied, where the sample was heated to the programming temperature (T prog ) and ≦10 mm min -1At a speed of , a specific programming strain (ε prog ), followed by an equilibration period of ≤10 min and cooling under constant strain to below the crystallization temperature (≤25 °C). After a further equilibration period of ≤10 min, the stress was released at this low temperature and the sample was allowed to cool to the recovery temperature (T rec During the recovery cycle, the specimen was subjected to a constant force of ≤0.1 N. T rec can be anywhere within the melting point range of the polymer, and T prog The shape fixation rate and recovery rate were calculated from the second and third cycles, and the results were analyzed. The shape recovery rate of the coated fiber was ≧95%.

[0214] To ensure and evaluate the long-term shape memory ability of these fibers, a shape memory cycle test was carried out approximately 100 times. The results showed that the shape recovery rate and the decrease in the shape fixation rate were the same throughout the 100 cycles. For practical reasons and to shorten the cycle time, the heating and cooling rates were set to 10°C min -1 The equilibration time was reduced to 1 minute.

[0215] The foregoing are merely some preferred possible embodiments of the present invention, and all equivalent structural modifications made by applying the present teachings are intended to be within the scope of this patent application.

[0216] Although the present invention has been described and illustrated with reference to specific embodiments, the present invention is not limited to these embodiments. Those skilled in the art will recognize that various changes and modifications can be made without departing from the true scope of the present invention as defined by the claims and the specification. Accordingly, all changes and modifications that come within the scope of the appended claims and their equivalents are intended to be embraced within the scope of the present invention.

[0217] Example 2: Shape-memory textile In this particular example of the invention, thermal programming of shape memory textiles incorporating coated shape memory polymer fibers is demonstrated using coated PEVA fibers. These fibers were first individually programmed before being incorporated into the textile. An exemplary textile is shown in Figures 4A and 4B.

[0218] The programming process involved heating the shape memory textile to 60° C., stretching it to a low programming strain of 50%, and then cooling it to about 25° C. This step established the temporary shape of the contained shape memory polymer fibers.

[0219] This example demonstrates the broader applicability of the disclosed technology by incorporating thermally programmed coated shape memory polymer fibers into a knitted cotton textile via weaving. Initially, the knitted textile incorporated these fibers with a diameter of 14 cm. Upon exposure to a temperature of 60°C, the textile significantly shrunk, decreasing in diameter from 14 cm to 10 cm. This change was caused by the activation of a shape recovery process in the SMP fibers within the coated shape memory polymer fibers.

[0220] To demonstrate the versatility of this technique, a shape-memory textile was subjected to a reprogramming step. In this process, the textile was reheated to 60°C, manually expanded to its original diameter of 14 cm, and then cooled to 25°C. This procedure reset the coated shape-memory polymer fibers to their new shape and temporarily retained it. Upon reheating to 60°C, the textile consistently returned to a diameter of 10 cm. This reprogramming and recovery cycle was successfully repeated five times, highlighting the durability and reliability of the shape-memory effect in the textile.

[0221] A key feature of this example is the insulating properties of the cotton component of the textile. This insulating property allows the SMP fibers to be safely heated and regain their shape, maintaining safety even when worn. Notably, in the case of the PEVA fibers, the initial programming of the shape-changing fibers occurred before they were incorporated into the textile, whereas subsequent cycles resulted in the reprogramming of the entire textile, including the integrated SMP fibers. This highlights the flexibility of the programming process, which works for both individual coated shape-memory polymer fibers and the composite shape-memory textiles that contain them. Furthermore, this demonstrates the thermally programmable nature of the employed textiles to directly fit and adjust to the subject's body.

[0222] This example highlights the revolutionary potential of thermally programmable shape memory textiles to create dynamic and adaptive fabrics, which opens up a variety of potential applications, such as adjustable garments or medical textiles, that exploit the textile's ability to conform to changing shapes and provide definable and reprogrammable pressure forces that are directly related to the programmed strain. [Explanation of symbols]

[0223] (1) Coated shape memory polymer fiber (cSMPF) (10) Core fiber (20) Non-stretchable covered yarn (30) Semicrystalline shape memory polymer (31) Crystalline rigid segment (32) Switching Segment (40) Covalently crosslinked shape memory polymer (50) Radical (60) Initiator (61) Cross-linker

Claims

1. A coated shape memory polymer fiber (1) (cSMPF), a core fiber (10) comprising a shape memory polymer (SMP), - a substantially inelastic covered thread (20), Including, The coated shape memory polymer fiber (1), characterized in that the substantially inelastic covered yarn (20) is wrapped around the core fiber (10) such that the maximum engineering strain of the core fiber (10) is reduced to or below the strain at the yield point of the uncoated core fiber (10).

2. The core fiber (10) comprises a shape memory polymer (SMP), the shape memory polymer being a thermally programmable shape memory polymer, and the programming temperature (T ｐｒｏｇ 2. The coated shape memory polymer fiber of claim 1, wherein the temperature is from 40°C to 80°C.

3. 3. The coated shape memory polymer fiber of claim 1 or 2, wherein the shape memory polymer (SMP), preferably the thermally programmable shape memory polymer, is a semi-crystalline shape memory polymer (SSMP) with a crystallinity of 3% to 70%.

4. 4. The coated shape memory polymer fiber of claim 3, wherein the semi-crystalline shape memory polymer (SSMP) is selected from the list comprising semi-crystalline polyesters, ethylene-co-monomer-polymers, di- or multi-block copolymers, or semi-crystalline ionomers.

5. 5. The coated shape memory polymer fiber according to claim 1, wherein the core fiber (10) is selected from a shape memory polymer selected from the group consisting of polycaprolactone, poly[ethylene-co-vinyl acetate] (PEVA), poly(ethylene-1-octene), trans-polyoctenamer-containing polycyclooctene (PCO / TOR), poly[ethylene-co-ethyl acrylate-co-maleic anhydride] (PEEAMA), poly[ethylene-co-(methyl acrylate)-co-(glycidyl methacrylate)] (PEMAGMA), perfluorosulfonic acid ionomer (PFSA), and amorphous multiblock alicyclic polyether urethane (PEU) consisting of poly(tetramethylene glycol) (PTMEG), 1,4-butanediol (1,4-BD), and methylenebis(p-cyclohexyl isocyanate) (H12MDI).

6. 6. The coated shape memory polymer fiber of claim 5, wherein the shape memory polymer comprises poly[ethylene-co-vinyl acetate] (PEVA), the poly[ethylene-co-vinyl acetate] being formed from a poly[ethylene-co-vinyl acetate] polymer (PEVAP), and the vinyl acetate content in the poly[ethylene-co-vinyl acetate] polymer is from 5% to 50% of the total weight of the polymer.

7. 7. The coated shape memory polymer fiber of claim 1, wherein the coated yarn (20) is selected from cotton, wool, silk, linen, viscose, acrylic, nylon, and polyester.

8. 8. The coated shape memory polymer fiber according to claim 1, wherein the stretchability of the coated shape memory polymer fiber is from 30 to 1000%.

9. 9. The coated shape memory polymer fiber according to claim 1, wherein the covering yarn (20) is wrapped around the core fiber (10) at a rate of 500 to 6000 turns per meter.

10. 10. The coated shape memory polymer fiber according to any one of claims 1 to 9, wherein the core fiber (10) is a multifilament fiber, preferably with a linear fiber density of 15 to 1000 dtex.

11. 11. The coated shape memory polymer fiber according to any one of claims 1 to 10, wherein the diameter ratio of the covering yarn to the core fiber is preferably in the range of 1:1 to 1:

20.

12. 12. The coated shape memory polymer fiber of claim 1, wherein the diameter of the core fiber is in the range of 50 to 500 μm.

13. 13. A method for producing the coated shape memory polymer fiber (cSMPF) of any one of claims 1 to 12, comprising the following steps: a) extruding the core fiber (10) of a core fiber precursor for shape memory polymers according to any one of claims 1 to 5, preferably together with a cross-linker or cross-linking agent; b) curing the extruded fibers, preferably under UV, beta or gamma radiation for covalent cross-linking, then c) winding a covering yarn (20) around the core fiber (10); 1. A method for producing a coated shape memory polymer fiber, comprising:

14. A shape memory fabric comprising a coated shape memory polymer fiber (cSMPF) comprising a core fiber (10) according to any one of claims 1 to 12 and a substantially inelastic covering yarn (20), The coated shape memory polymer fiber (cSMPF) a) an interwoven or intertwined shape memory mesh network of cSMPFs forming an operatively linked structure; and / or b) a shape memory inlay disposed in the second fabric; placed in A shape memory fabric characterized in that the maximum engineering strain of the core fiber (10) is reduced to or below the strain at the yield point of the uncoated core fiber (10).

15. 13. A shape memory textile comprising a coated shape memory polymer fiber (cSMPF) according to any one of claims 1 to 12 and at least further fabrics and / or further fibers, wherein the cSMPF is arranged in and / or on the shape memory textile by knitting, weaving, braiding, embroidery, composite techniques or as a 3D textile structure, A shape memory textile, characterized in that the maximum engineering strain of the core fiber (10) is reduced to or below the strain at the yield point of the uncoated core fiber (10).

16. 16. A method for producing a shape memory fabric according to claim 14 and / or a shape memory textile according to claim 15, comprising the steps of: a) providing a coated shape memory polymer fiber (cSMPF) according to any one of claims 1 to 12, then b) disposing the coated shape memory polymer fiber (cSMPF) in and / or on a textile or fabric, preferably by knitting, weaving, braiding, embroidery, composite techniques, or 3D textile structuring; A method for producing a shape memory fabric and / or a shape memory textile, comprising:

17. 14. Use of the coated shape memory polymer fiber according to any one of claims 1 to 13 in compression garments, orthopedic bandages, braces, posture corrective garments, push-up garments, corsets and corsages, and sports garments.

18. 16. A thermally programmable textile, such as a thermally programmable textile for technical, medical, orthopedic, industrial, sports or leisure applications, comprising a coated shape memory polymer fiber according to any one of claims 1 to 12, or a shape memory fabric according to claim 14, or a shape memory textile according to claim 15.

19. 20. Use of a thermally programmable textile according to claim 18 as a medical or orthopedic garment, preferably thermally programmable repeatedly by heating to 40 to 70°C on the body of a subject.

20. 20. Use of a thermally programmable textile according to claim 18, which is repeatedly thermally programmable, preferably by heating to 40 to 70°C on the body of a subject, as sports or leisure clothing.

21. 16. A thermally programmable fabric, such as a shape memory fabric for technical, medical, orthopedic, industrial, sports or leisure applications, comprising a coated shape memory polymer fiber according to any one of claims 1 to 12, or a shape memory fabric according to claim 14, or a shape memory textile according to claim 15.

22. 22. Use of the thermally programmable fabric of claim 21, preferably repeatedly thermally programmable on the body of a subject by heating to 40 to 70°C, as a medical or orthopedic garment.

23. 22. Use of the thermally programmable fabric of claim 21, preferably repeatedly thermally programmable on the body of a subject by heating to 40 to 70°C, as sports or leisure clothing.

Images