BE1026302A1 - Copolymer - Google Patents

Abstract

A fiber-forming copolymer, wherein the copolymer is a linear copolymer comprising a polyurethane and PDMS. Fiber and textile comprising the copolymer. Also a method of making the copolymer, the method comprising: i) reacting a diisocyanate with a C1 to C10 polyether to form a prepolymer; and ii) reacting the prepolymer with a chain extender comprising PDMS.

Description

copolymer

The invention relates to a copolymer which can form fibers, in particular a fiber-forming copolymer comprising polyurethane and PDMS. The invention further relates to a fiber, the use of a fiber, a textile comprising the fiber and a method of making the copolymer.

It would be desirable to develop alternatives to the perfluorinated and polyfluorinated compounds currently used in many water resistant garments since these compounds are widely documented to have a detrimental effect on the environment while causing health problems. In addition, a wet treatment used in the manufacture of textiles faces multiple pressures in the form of attempts to reduce the amounts of water, chemicals and energy used in the manufacture of textiles in order to achieve sustainability (durability) and ultimately a “zero waste” technology.

Polyurethanes are versatile polymers with a wide range of uses. As a result, the global market for polyurethanes exceeds $ 33 billion. Foams dominate the market while elastomers, which are often found in textile fibers, make up around 12% of total polyurethane sales. Elastomeric textile fibers typically comprise at least 85% by weight of polyurethane and are characterized by their high extensibility and excellent recovery. These innate properties of polyurethane fibers are due to the alternating hard (diisocyanate) and soft (polyol) segments within the structure of the polymer.

Polyurethane foams were combined with polydimethylsiloxane (PDMS). The PDMS is composed of repeated silicon-oxygen bonds forming a siloxane skeleton which allows rotation so that the non-polar methyl groups are projected on the external surface, leading to a highly polymeric air-polymer interface.

BE2018 / 5359 hydrophobic. As such, it may be beneficial to include PDMS in polyurethanes, to improve the water repellency of the polymer. However, it is not possible to combine polyurethane with PDMS in a fiber, prohibiting the use of polyurethane-PDMS copolymers in the textile industry.

The invention aims to overcome or at least improve certain aspects of this problem.

Consequently, in a first aspect of the invention, a fiber-forming copolymer is proposed, in which the copolymer is a linear copolymer comprising a polyurethane and PDMS. It has been found that by ensuring linearity of the polyurethane and PDMS copolymer, elastomeric water-repellent fibers can be formed by a variety of techniques. Without wishing to be bound by a theory, it is believed that by proposing linear polymer patterns, an overlap between the patterns results in an interaction between them conferring strength and structure on the fibers.

As used herein, the terms "copolymer" and "polymer" are used interchangeably when referring to the copolymer of the invention.

The inherent water resistance of the fibers formed from the copolymer is particularly advantageous since such properties are normally added to the fabric by the addition of a water-repellent coating during finishing. By communicating such functionality at the fiber formation stage, the manufacturing process can be simplified, with a consequent reduction in water, chemicals and energy. This makes the process more sustainable. As the water-repellent properties are inherent in the fiber, they will not be reduced over time, by damaging the coating in use. In addition, since most of the coatings used are based on fluorocarbon, the copolymers of the invention have the additional advantage that they can provide water-repellent products, without the need to use potentially harmful fluorocarbon products.

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The copolymer can generally be obtained by reacting a diisocyanate with a C1 to C10 polyether, and optionally a chain extender.

The polyether can be straight chain or branched or cyclic. Often, the polyether will be straight chain to promote molecular alignment within the copolymer. Often, the C1 to C ₁₀ polyether will be a C ₂ to C ₅ polyether. For straight chain polyethers, the polyether will often be chosen from polyethylene glycol (PEG) and / or polypropylene glycol (PPG).

Often, the polyether has a molecular weight in the range of 800 to 3,500 g / mole, often 1,000 to 3,000 g / mole. When the polyether is PTHF, it will often be present in the range of molecular weights above. It has been found, when casting processes are used, that for copolymers formed from C1 to C10 polyethers, in particular for copolymers formed from PTHF, below these molecular weights, the formation film may be affected, the copolymer remaining sticky to the touch.

In many cases, the diisocyanate comprises an aromatic diisocyanate, so that a nucleus of the diisocyanate is an aromatic moiety. As used herein, the term "diisocyanate ring" is intended to refer to the diisocyanate structure excluding the two isocyanate groups, for example in a generic diisocyanate structure OCN-R-NCO, the diisocyanate ring is "R". In many cases, the diisocyanate is chosen from toluene diisocyanate, methylene diphenyl diisocyanate and their combinations because of their rigidity, which contributes to maintaining the linearity of the copolymer promoting the intermolecular interaction between polymer chains. The diisocyanate will often be methylene diisocyanate because of its good commercial availability and ease of handling.

The chain extender will often include a PDMS, the chain extender will often include PDMS and a diol, so that the copolymer can be obtained by reacting a

BE2018 / 5359 diisocyanate with a C 1 to C 10 polyether, such as PEG, PPG or PTHF in the presence of PDMS and optionally a diol. This creates a copolymer with the beneficial characteristics of both polyurethane and PDMS. Polyurethane-PDMS copolymers exhibit the high water and heat resistance of PDMS while preserving the favorable mechanical properties of the polyurethane. Without wishing to be bound to a theory, it is believed that the increase in the rate of PDMS (whether by increasing the percentage present in the chain extender, or increase in the ratio of chain extender to other polymer units) increases the hydrophobicity due to the migration of the intrinsically hydrophobic PDMS regions of the polymer to the surface of the fibers.

Without wishing to be bound by theory, it is believed that the polyether (such as PTHF) reacts with the diisocyanate to form a prepolymer, and that the prepolymer will generally include alternating polyether diisocyanate units. In many cases, the diisocyanate will be present in a slight excess, so that the prepolymer includes diisocyanate end groups. As used herein, the term "slight excess" is intended to refer to an excess in the range of 0.1 to 3% by mole, often 0.1 to 1% by mole. After the prepolymer is formed, PDMS and optionally the diol are added, and they act as chain extenders, connecting the prepolymer units. Consequently, it can be said that the copolymer is formed from blocks of prepolymers joined by chain extenders comprising PDMS and optionally a diol. It can be said that the chain extender comprises 100% PDMS, or in the range of 100% to 10%, or in the range of 75% to 20% per unit of chain extender, so that 100 % of PDMS corresponds to the fact that the entire chain extender is PDMS and 50% corresponds to that 50% of the chain extender units are PDMS and 50% is diol. It will often be common for the chain extender to include in the range of 20-30% PDMS. The chain extender

BE2018 / 5359 provides a "soft" segment within the copolymer ensuring flexibility within the polymer chain and conferring improved processability of the copolymer.

The ratio of chain extender to prepolymer is often in the range of 6: 1 to 1: 1 of prepolymer to chain extender, often from 3: 1 to 1: 1 or 2: 1 to 1: 1.

Often PDMS is PDMS terminated by hydroxy. Often PDMS has a molecular weight in the range of 400 to 1,600 g / mole, in some cases 500 to 1,000 g / mole or 600 to 800 g / mole.

The diol will generally comprise a linear aliphatic diol, since this chain extender confers a linear structure on the copolymer, allowing the length of the polymer to be extended. However, non-linear diols can be used occasionally. Often the diol will comprise a C2 to C10 diol, often a C2 to C6 diol, and the diol can be selected from linear aliphatic diols, aromatic diols, aromatic aliphatic diols, alkenes diol and combinations thereof. Specific examples of diols include propanediols, butanediols, pentanediols, hydroquinone, benzenedialcanols, butene diols, pentene diols, and combinations thereof.

The aliphatic diols and alkenes diol will often be substituted for the terminations, such that a propanediol will typically be a 1,3-propanediol, or a butenediol will often be a 1,4butanediol. For alkenediols, there will usually be only one alkene functionality, although two or more C = C may be present. Often the alkene group will be a trans group to preserve the linearity of the polymer formed, although cis-alkenes may also be present. The alkene can appear at any point in the chain, although it is often central or substantially central. For example, a butenediol would often be a 2-butenediol. The alkenediol will generally have a general structure (I):

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HO n OH where the n may be the same or different and may be in the range of 0 to 8, provided that the total chain length does not exceed Cw.

The benzenedialcanol can be a 1,4-, 1,3- or 1,2benzenedialcanol, although it is often a 1,4-benzenedialcanol to maintain the linearity of the overall polymer formed. The alkyl chain in benzenedialcanol will generally be a straight chain, and will often be independently a C1 to C2 chain, so that the benzenedialcanol will often be selected from benzenedimethanol or benzenediethanol. This minimizes the chain flexibility introduced. Often, the benzenedialcanol will be a 1,4-benzenedimethanol. Often, benzenedialcanol will be of structure (II):

HO

OH (H) where the n's can be the same or different and can be in the range from 0 to 4, provided that the total chain length does not exceed Ci ₀ .

In many examples, the diol includes a C4 diol, such as butanediol or butenediol. In particular, 1,4-butanediol or 1,4-butenediol (often a trans 1,4-butenediol). Butanediol will often be used, such as 1,4-butanediol.

The molecular weight of the copolymer will often be in the range of 50,000 to 125,000 g / mole, more often in the range of 70,000 to 100,000 g / mole. Molecular masses in this range result in polymers which are of sufficient length to

BE2018 / 5359 confer good alignment and good intermolecular interaction between polymers on a molecular scale. This takes into account fiber formation, and results in solid fibers of good structure.

The melting point will often be in the range of 200 to 250 ° C, often 200 to 230 ° C. Melting points can be controlled by changing the length of the prepolymer chain and the ratio of prepolymer to chain extender. The copolymer will generally have a range of melt processing temperatures of 100-200 ° C, often 120-160 ° C. This range is important because for many treatment methods, the copolymer must be in liquid form. A wide range of melt processing temperatures corresponds to a larger range of temperatures over which the copolymer can be processed. As used herein, the term "melt processing temperature range" is intended to mean a temperature range where the lower limit is the melting point of the polymer and the upper limit is the decomposition point. To dispel doubt, the copolymers of the invention will generally decompose in the liquid state, without vaporization. Often the decomposition temperature will be in the range of 320 to 400 ° C, often 320 to 350 ° C, this provides a good processing window for melt processing, if this method is used.

The copolymer can respond to a structure of formula (III):

R ²

O

1.NH

NH R '

O

O

-R \

NH NH

I-O

O

1 NH

NH - R '

O

X NH

NCO

- * p (III) in which R ¹ is a diisocyanate ring,

BE2018 / 5359 ₂ HO ^ O ^

R ² is independently chosen from among / ^H 3 ^C CH3 \

I / S) ^H ' ^O / q

O n O

R ³ is independently selected from and m is independently in the range of 10 to 50, because in these ranges, the PTHF chains are of sufficient molecular mass to form excellent cast films, as described above, n is in the range from 1 to 10, often from 4 to 6, often from 4, p is independently in the range from 2 to 55, often from 20 to 45 or 22 to 44, and q is 5 to 15.

Often the ratio of the sum of + / ^H 3C chA / ^H 3CcH3 \ / \ (.Si -----) - (.Si) HO nO ^z ' ^OH : + is in the range of 100: 1 to

1: 9, often from 3: 1 to 1: 3, often from 2: 1 to 1: 2 or around 1: 1.

In a second aspect of the invention, a fiber is proposed comprising a copolymer according to the first aspect of the invention. The fiber will often have a diameter in the range of 0.5 to 5 μm, often 1 to 3 μm. Such fibers are strong and flexible. The elasticity will often be in the range of 30 to 400%, often from 75 to 300%, often from 100 to 200%. Elasticities in this range give textiles that stretch, do not sag, and create support for the wearer.

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In a third aspect of the invention, there is provided a textile comprising a fiber according to the second aspect of the invention. Such textiles are generally breathable, elastomeric and water-repellent. This makes them excellent for clothing intended for outdoor activities, in particular clothing for outdoor sports activities. A typical measure of water repellency is the measurement of the contact angle, values greater than 90 ° being considered water repellents, and ranges approaching this are indicative of hydrophobicity. The contact angle of textiles comprising the described copolymers will often be greater than 70 °, often greater than 90 °, often in the range of 90 to 170 °, or 100 to 150 ° or 130 °.

The textile can be woven or nonwoven, and it will often be nonwoven fabrics because the copolymers are particularly suitable for melt processing, solution blowing and electrostatic spinning, and these processes form nonwoven fabrics.

In a fourth aspect of the invention, the use of a fiber according to the second aspect of the invention is proposed in the manufacture of a textile.

In a fifth aspect of the invention, there is provided a method for manufacturing a copolymer according to the first aspect of the invention, the method comprising:

reacting a diisocyanate with a C1 to C10 polyether such as PEG, PPG or PTHF to form a prepolymer; and reacting the prepolymer with a chain extender comprising PDMS.

This process can be carried out at low temperature, for example in the range of 80 to 120 ° C, often around 100 ° C.

The method can further include forming a copolymer film, where the film can be formed by casting, extrusion or calendering. The film will often be formed by casting due to the simplicity and the great applicability of this technique.

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In a sixth aspect of the invention, a method of manufacturing a fiber according to the second aspect of the invention is proposed, comprising a treatment in the molten state or electrostatic spinning of a copolymer according to the first aspect of the invention. 'invention. The melt processing will often be at a temperature in the range of 200 to 400 ° C, often 200 to 350 ° C, coinciding with the range of melt processing temperatures of the copolymers of the invention. When the fibers are to be formed by electrostatic spinning, this is often done in a mixture of dimethylformamide: tetrahydrofuran solvent, often in a ratio in the range of 5: 1 to 1: 1, often in a range of 3: 2 to 1: 1 to ensure optimal solubility of the copolymer.

Consequently, the invention can relate to:

• a fiber-forming copolymer, wherein the copolymer is a linear copolymer comprising a polyurethane and PDMS obtainable by reacting methylene diphenyl diisocyanate with a PTHF of molecular weight in the range of 800 to 3,500 g / mole and an extender of chain comprising hydroxy terminated PDMS of molecular weight in the range of 400 to 1000 g / mol and optionally butanediol, in which PDMS is present in the range of 100 to 10% of chain extender and in which the physical properties of the copolymer include a molecular weight in the range of 50,000 to 125,000 g / mole, a melting point in the range of 200 to 250 ° C, a range of melt processing temperatures in the range of 120 to 160 ° C, a decomposition temperature in the range of 320 to 350 ° C.

• a fiber comprising a copolymer as described, with a diameter in the range of 0.5 to 5 μm and an elasticity in the range of 35 to 365% of average extension.

• a textile comprising a nonwoven fabric of a fiber as described, in which the contact angle is in the range of 70 to 170 °.

BE2018 / 5359 • a process for the manufacture of a copolymer, the process comprising: reacting methylene diphenyl diisocyanate with a PTHF of molecular weight in the range of 800 to 3,500 g / mol to form a prepolymer; reacting the prepolymer with a chain extender comprising hydroxy-terminated PDMS of molecular weight in the range of 400 to 1,000 g / mol and optionally butanediol, in which PDMS is present in the range of 100 to 10% chain extender; and forming a copolymer film by casting.

• a process for manufacturing a fiber as described, comprising melt processing, solution blowing or electrostatic spinning of the copolymer, in which the melt processing is in the temperature range from 200 to 350 ° C and the electrostatic wiring is in a mixture of dimethylformamide: tetrahydrofuran solvent of 3: 2.

Unless otherwise indicated, each of the integers described can be used in combination with any other integer as those skilled in the art will understand. In addition, although all aspects of the invention preferably "include" the features described in connection with this aspect, it is specifically contemplated that they may "consist" or "consist essentially" of these features outlined in the claims. In addition, all terms, unless specifically defined here, are intended to have their meanings commonly understood in art.

Furthermore, in the discussion of the invention, unless otherwise indicated, the disclosure of alternative values for the upper or lower limit of the allowable range of a parameter, should be interpreted as an implicit declaration that each intermediate value of said parameter, lying between the smallest and the largest of the alternatives, is itself also disclosed as a possible value of the parameter.

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In addition, unless otherwise indicated, all the numerical values appearing in this application must be understood as being modified by the term "approximately".

In order that the invention may be more easily understood, it will be described further with reference to the figures and specific examples below.

Figure 1 is a schematic representation of the polymerization technique of samples A to D. In the diagram, the PDMS: butanediol ratio is 1: 1 (50% PDMS - as in sample A), so that PDMS and butanediol form an equal number of chain extender groups. When a higher percentage of PDMS is present, it will appear more frequently as a chain extender between the copolymer units.

Figure 2 is an ATR-FTIR of PDMSpolyurethane copolymers with various percentages of PDMS (5%, 10%, 20%, 50%, 100%). As the percentage of PDMS increases, so does the intensity of the siloxane peak at approximately 1,090 cm ^-1 ;

Figure 3 is a GPC of a 20% polyurethane PDMS copolymer having a molecular weight of approximately 75,000;

Figure 4 is a DSC for samples A and B (50% and 100% PDMS, respectively);

FIG. 5 is two SEM images of sample A (scale 50 μm and 20 μm);

FIG. 6 is two SEM images of sample B (scale 50 μm and 20 μm);

FIG. 7 is an SEM image of the sample C (100 μm scale);

Figure 8 shows contact angles for samples A and C;

Figure 9 is a SEM image of sample D (scale

100 μm); and

BE2018 / 5359 Figure 10 is two SEM images of sample C ’(100 μm and 20 μm scale).

Examples

Polymer synthesis

Four samples of the copolymer were prepared as sketched below. PTHF was chosen as the representative polyether for these experiments. The general synthesis process was to combine PTHF (M _# 2900) and MDI to form a prepolymer, and then a solution of PDMS and butanediol was added with stirring to form the final polymer as shown in Figure 1. On In FIG. 1, an equimolar solution of PDMS and butanediol is added, so that the chain extenders are in a butanediol: PDMS ratio of 1: 1. Sample A

Polytetrahydrofuran (Mn 2900, 6 g, was dissolved

2.1 mmol) in toluene (20 mL) with stirring under a protective nitrogen atmosphere. Methylene diphenyl diisocyanate (0.62 g, 2.5 mmol) was added with stirring and allowed to dissolve. The solution was heated under reflux (100 ° C, 90 minutes), during which time an increase in viscosity of the solution was observed. Butanediol (0.07 mL, 0.8 mmol) was added dropwise together with polydimethylsiloxane (0.4 mL, 0.7 mmol) with stirring, and the solution was heated under reflux (100 ° C) for an additional 90 minutes. The resulting solution was then poured into a shallow box and allowed to form a film.

Sample B

Polytetrahydrofuran (Mn 2900, 6 g, was dissolved

2.1 mmol) in toluene (20 mL) with stirring under a protective nitrogen atmosphere. Methylene diphenyl diisocyanate (0.62 g, 2.5 mmol) was added with stirring and allowed to dissolve. The solution was heated under reflux (100 ° C, 90 minutes), during which time an increase in viscosity of the solution was observed. Polydimethylsiloxane (0.8 mL, 1.5 mmol) was added with stirring, and

BE2018 / 5359 the solution was heated under reflux (100 ° C) for an additional 90 minutes. The resulting solution was then poured into a shallow box and allowed to form a film.

Sample C

Polytetrahydrofuran (Mn 2900, 6 g, was dissolved

2.1 mmol) in toluene (20 mL) with stirring under a protective nitrogen atmosphere. Methylene diphenyl diisocyanate (0.62 g, 2.5 mmol) was added with stirring and allowed to dissolve. The solution was heated under reflux (100 ° C, 90 minutes), during which time an increase in viscosity of the solution was observed. Butanediol (0.1 mL, 1.1 mmol) was added dropwise together with polydimethylsiloxane (0.2 mL, 0.35 mmol) with stirring, and the solution was heated under reflux (100 ° C) for an additional 90 minutes. The resulting solution was then poured into a shallow box and allowed to form a film.

Sample D

Polytetrahydrofuran (Mn 2900, 6 g, was dissolved

2.1 mmol) in toluene (20 mL) with stirring under a protective nitrogen atmosphere. Methylene diphenyl diisocyanate (0.62 g, 2.5 mmol) was added with stirring and allowed to dissolve. The solution was heated under reflux (100 ° C, 90 minutes), during which time an increase in viscosity of the solution was observed. Polydimethylsiloxane (0.2 mL, 0.35 mmol) was added with stirring, and the solution was heated under reflux (100 ° C) for an additional 90 minutes. The resulting solution was then poured into a shallow box and allowed to form a film.

Sample E

Polytetrahydrofuran (Mn 2900, 6 g, was dissolved

2.1 mmol) in toluene (20 mL) with stirring under a protective nitrogen atmosphere. Methylene diphenyl diisocyanate (0.62 g, 2.5 mmol) was added with stirring and allowed to dissolve. The solution was heated under reflux (100 ° C, 90 minutes), during which time

BE2018 / 5359 observed an increase in viscosity of the solution. Butanediol (0.2 mL, 2.26 mmol) was added dropwise with stirring, and the solution was heated under reflux (100 ° C) for an additional 90 minutes. The resulting solution was then poured into a shallow box and allowed to form a film.

Electrostatic wiring tests

Solution preparation

For samples A, B, C and E, polyurethane (6.0 g) was cut into small pieces and dissolved in THF / DMF (30 mL, 2: 3 (v: v)) with shake in a sealed container at room temperature for 24 hours to give a colorless solution. 10% w / v solutions were prepared and attempts were made to electrostatic spinning the resulting solutions.

For sample C ', a 20% w / v solution was prepared using polymer C by the same method as above. For D, a 20% p: vol solution was again prepared by the same process. Solution spinning

Electrostatic spinning was performed in horizontal alignment using a KD Scientific electrostatic spinning feeder and Glassman High Voltage Inc power supply using a 10 mL syringe (Fortuna and Graff) equipped with '' a Luer lock metal needle with blunt end (18 gauge). A voltage of 18 kV and a flow rate of 3 mL h ^{-1 were used} . A tip-to-manifold distance of 150 mm was used and canvases were collected on squares (100 χ 100 mm) of aluminum foil. Methodology

Melting and decomposition points

The thermal properties of the polymer films were measured by differential scanning calorimetry (DSC for “Differential Scanning Calorimetry”) using a DSC Q20 V24.10 (TA Instruments) under a nitrogen atmosphere. Size 5-10 mg polymer samples were pressed and stowed in aluminum tubs and heated from 0 to

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250 ° C at a rate of 10 ° C min ^-1 to determine the thermal behavior in each case.

Contact angle

The angle of static contact of water with the surface of the membrane was measured using a sessile drop method with a KSV CAM200 goniometer (KSV Instruments Ltd.) at room temperature. Drops of distilled water (5 μL) were introduced into the surface of the membrane and they were measured once per second for 20 s, taking the mean contact angle values between 3 and 20 s. Five measurements were taken at different locations on the membrane surface for each sample and the standard deviations and coefficients of variation were calculated.

Water vapor permeability test

The membranes were tested by covering test boxes 76 mm in internal diameter and 50 mm in height. The cans were placed on a movable turntable which can rotate at low speeds for extended periods. The apparatus was housed in a test environment with constant temperature and humidity, 20 ± 2 ° C and 65 ± 2%, respectively.

We compared samples to a reference fabric having the following specifications:

woven polyester fabric wire diameter 32 μm mesh opening 18 μm wire density per cm 196.1 % of free area 12.5 The tests were repeated at least three times. We transferred from

water at a temperature of 20 ± 2 ° C in the circular boxes up to a water level which was 10 ± 1 mm below the bottom surface of the fabric. The box was then covered with the membrane which was secured with an elastic tape. The boxes were then placed on the corresponding position on the turntable. The turntable turns

BE2018 / 5359 with a speed below 6 m / min. The boxes were rotated for a minimum of 1 hour to allow the balance to form. The boxes were then weighed on an accurate balance to the nearest 0.001 g. The boxes were returned to the tray and allowed to rotate further for an extended period which should exceed 5 hours. The samples were then re-weighed.

We then calculated the permeability to water vapor by:

WVP

Âm

A t where Am is the change in mass in grams; A is the area of the box in m ² and fest the time in hours.

The WVP index is then given by the equation:

X 100 where WVP _S is the transmission of the sample and WVP _R is the transmission of the reference tissue tested in the same period. Mechanical properties

The tensile strength and elongation of the electrostatically spun membranes were tested using a Titan Universal (James Heal) strength testing machine equipped with a 100 N load cell. The tests were carried out according to BS EN ISO 9073-18: 2008 using the following parameters: gauge length (jaw separation), 20 mm; extension rate, 10 mm / min; and without pre-tension. The specimens were fixed to square cardboard sample holders so that the test area was 400 mm ² . The sample holders were cut at the sides so that the sample was only stowed up and down where the sample holder was fitted to the jaws of the machine. The measurements were repeated three times for each membrane, taking specimens for different areas of the membrane each time. We only ran the tests in one direction because we didn't plan

BE2018 / 5359 no directional variation for membranes formed using the horizontal electrostatic spinning setting described in this project.

Molecular weight

The polymer was dissolved in dimethylformamide (1 mg of polymer in 1 mL of solvent), and filtered to remove any impurities before being subjected to gel permeation chromatography (Waters).

Synthesis of copolymer

A range of polyurethanes was synthesized using variable molar equivalents of PDMS between 5 and 100%. An ATR-FTIR shown in Figure 2 shows both aromatic and aliphatic CH stretches around 3,000 cm ^-1 , together with high absorbance due to siloxane bonds (~ 1,090 cm ^-1 ) and a peak due to groups silyl methyl in the imprint region.

Molecular mass determination

Polyurethane-PDMS copolymers (5, 10, 20, 50 and 100%) were evaluated together with a standard polyurethane by gel permeation chromatography (GPC for “Gel Permeation Chromatography”) in order to determine their molecular mass. As shown in Figure 3, the polymers analyzed had a molecular weight in the region of 115,000 ± 5,000 with M _n ~ 75,000 ± 5,000.

Physical properties of samples A to E

It was found that fibers from copolymers A to E had the properties shown in Table 1.

Sample % of PDMS * Fusion point (° C) Decomposition point (° C) Contact angle (°) Water vapor permeability AT 50 205 340 B 100 (1.5 mmol) 210 332 - VS 25 110 ± 2 21.74 ± 1.97

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- 9 VS' 25 (20% p: vol) 110 ± 2 D 100 (0.35 mmol, 20% p: vol) 128 ± 12 E 0 72 ± 5

*% of PDMS is the% by weight of PDMS based on the PDMS: butanediol ratio, for example a copolymer with 20% of PDMS has a PDMS: butanediol ratio of 1: 4. Samples were prepared at 10% w: volume unless otherwise indicated.

From this it can be seen that in terms of water repellency, as determined by the static contact angle, there is a complicated relationship which depends not only on the fiber morphology but also on the amount of siloxane present. There is a clear relationship that an increase in the amount of siloxane in the polymer leads to an increase in the static contact angle. However, this is complicated by the introduction of a surface roughness. The formation of nanofibers by electrostatic spinning has the effect of increasing the surface roughness and subsequently increasing the static contact angle. A comparison of samples A and B illustrates that a good range of melting points can be obtained regardless of the PDMS level. The ability to produce polymers with processing windows exceeding 100 ° C ensures good processing of the polymer into a fiber, and as shown in Figure 4, a DSC for samples A and B. Sample A shows a slightly lower melting temperature (204.9 ° C) than sample B. This can be explained by the higher percentage of PDMS in sample B, leading to an increase in potential polymer conformations, thereby reducing the intermolecular interactions and subsequently the melting point of the polymer.

If necessary, the melting point characteristics of the copolymer can be increased by increasing the PTHF and / or the length of the prepolymer chain.

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As can be seen from a comparison of samples B and D, a reduction in the rate of chain extender does not prevent the formation of fibers (Figures 6 and 9). Figures 9 and 6 both show that fibers can be formed, Figure 9 illustrating a porous fabric with microfiber formation, and Figure 6 a fabric of solid fibers.

Fiber quality

In order to investigate the ability of samples A, B and C to form fibers, electrostatic spinning tests were undertaken. It has been found that under the conditions used, in the absence of PDMS, fiber formation does not occur.

Figure 5 shows the results for sample A. Fine fibers approximately 100 to 200 nm in diameter are produced, traveling between globular features, and this shows that the fibers can be formed but that further optimization would be necessary to produce defect-free fibers. The results for sample B are shown in Figure 6, and this sample has much larger fibers around 1 to 2 μm in diameter, proving that fiber formation is possible using sample B. The figure 7 shows that a fibrous network can be formed with the sample C, indicating that with further optimization, it is possible to produce separate fibers. This is highlighted in FIG. 10 which illustrates the sample C ′, of higher concentration of polymer. This sample has more clearly defined fibers than sample C (Figure 7). Thus, the results shown in Figures 5 to 7 and 10 show that these copolymers are capable of forming fibers.

hydrophobia

As noted above, the contact angle for sample E, not containing PDMS, is 72 °, to be compared with higher, more hydrophobic values for samples C and D (FIG. 8). This indicates that as the PDMS content increases, the observed contact angle also increases. One thinks that

BE2018 / 5359 this is due to the migration of the PDMS regions of the polymer to the surface of the fibers so that as the PDMS content is increased, the amount of PDMS on the surface of the leading fiber is increased subsequently to an increase in the contact angle. However, beyond a certain PDMS concentration, the surface roughness may be reduced, which could lead to a reduction in the angle of contact with water. While a contact angle of 128 ° was recorded for sample D containing 100% PDMS, it is believed that this is due to the rough topography of the sample and not simply to the amount of PDMS present.

The water repellency of a product is generally measured using a contact angle test. A contact angle considered to be truly water repellent is 90 ° or more. This can be achieved for copolymers by regulating the PDMS concentration, either by regulating the relative PDMS: diol ratio, or by regulating the relative chain extender: prepolymer ratio.

Water vapor permeability

Sample C had a water vapor permeability of 21.74, indicating breathability. A thin cast film of sample C exhibited negligible breathability indicating that it is the fine fibrous nature formed during the electrostatic spinning of the sample which is the key to its breathability.

It will be appreciated that the products, methods and uses of the invention are capable of being implemented in a variety of ways, only a few of which have been illustrated and described above.

Claims (36)

claims 1. A fiber-forming copolymer, wherein the copolymer is a linear copolymer comprising a polyurethane and PDMS. 2. Copolymer according to claim 1, obtainable by reacting a diisocyanate with a C1 to C10 polyether and a chain extender. 3. Copolymer according to claim 2, in which the C1-C10 polyether is chosen from PTHF, PEG, PPG and their combinations. 4. The copolymer according to claim 1, in which the C 1 to C ₁₀ polyether is PTHF. 5. The copolymer of claim 4, wherein the polyether is of molecular weight in the range of 800 to 3500 g / mole. 6. Copolymer according to any one of claims 2 to 5, in which the diisocyanate comprises an aromatic diisocyanate. 7. Copolymer according to claim 6, in which the diisocyanate is chosen from toluene diisocyanate, methylene diphenyl diisocyanate and combinations thereof. 8. Copolymer according to any one of claims 2 to 7, in which the chain extender comprises PDMS. 9. Copolymer according to any one of claims 2 to 8, in which the chain extender comprises PDMS and a diol. 10. The copolymer according to any of claims 2 to 8, wherein the chain extender comprises in the range of 100 to 10% PDMS. 11. Copolymer according to any one of claims 8 to 10, in which the PDMS is PDMS terminated by hydroxy. 12. The copolymer of any of claims 8 to 11, wherein the PDMS is of molecular weight in the range of 400 to 1,000 g / mol. BE2018 / 5359 13. Copolymer according to any one of claims 9 to 12, in which the diol comprises a linear aliphatic diol. 14. The copolymer according to any of claims 9 to 13, wherein the diol comprises a C2 to Cß diol. 15. Copolymer according to any one of claims 9 to 14, in which the diol comprises butanediol. 16. A copolymer according to any preceding claim, of molecular weight in the range of 50,000 to 125,000 g / mol. 17. A copolymer according to any preceding claim, with a melting point in the range of 200 to 250 ° C. 18. A copolymer according to any preceding claim, of melt processing temperature in the range of 120 to 160 ° C. 19. A copolymer according to any preceding claim, with a decomposition temperature in the range of 320 to 350 ° C. 20. Copolymer according to any preceding claim, of structure of formula III): R ² O i_NH NH r '' NH NH _1x NH NH R ' 4 / m O ' ^J p xR \ NH ^NCO III in which R1 is a diisocyanate ring, R ² is independently chosen from HO ^ O ^ and, H ^H 3Ç CH ₃ \ \ / ³ I .Si — J ^O 'q BE2018 / 5359 3 --- O n O R ³ is independently selected from and m is independently in the range of 10 to 50, n is in the range of 1 to 10, p is independently in the range of 2 to 55, and q is 5 to 15. 21. The copolymer according to claim 20, in which n is 4. 22. The copolymer of claim 20 or claim 21, wherein p is independently in the range of 20 to 45. 23. Copolymer according to any one of claims 20 to 22, in which the ratio of the sum of / ^h 3C ChA / ^H 3C CH3 \ Μ Μ \ —J- I ^ Si — J —O ^ no ^ ho nO ^z ' ^O q ^H ' ^O q +: + is in the range of 3: 1 to 1: 3. 24. The copolymer of claim 23, wherein the ratio is from 2: 1 to 1: 2. 25. Fiber comprising a copolymer according to any preceding claim. 26. The fiber of claim 25, with a diameter in the range of 0.5 to 5 microns. 27. Fiber according to claim 25 or claim 26, of elasticity in the range of 30 to 400%. 28. Textile comprising a fiber according to any one of claims 25 to 27. 29. The fabric of claim 28, wherein the contact angle is in the range of 70 to 170 °. BE2018 / 5359 30. The fabric of claim 28 or claim 29, comprising a nonwoven fabric. 31. Use of a fiber according to any one of claims 25 to 27, in the manufacture of a textile. 32. A method of manufacturing a copolymer according to any one of claims 1 to 24, the method comprising: i) reacting a diisocyanate with a C1 to C10 polyether to form a prepolymer; and ii) reacting the prepolymer with a chain extender comprising PDMS. 33. The method of claim 32, further comprising forming a copolymer film. 34. The method of claim 33, wherein the film is formed by casting. 35. A method of manufacturing a fiber according to any one of claims 25 to 27, comprising the treatment in the molten state or the electrostatic spinning of a copolymer according to any one of claims 1 to 24. 36. The method of claim 35, wherein the melt processing is in the temperature range of 200 to 350 ° C.