Description:FIELD OF THE INVENTION
[0001] The present disclosure relates to an exfoliated Transition Metal Dichalcogenides (TMDs) as a reinforcing agent for polymer composites. Specifically, the present disclosure relates to a TMD exfoliated with a tri-block copolymer (TBCP) and to a method of functionalizing the TMD with a tri-block copolymer. The present disclosure also relates to a composite polymer comprising the TBCP.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Epoxy resin has been identified as a versatile polymer that can be used in several industrial applications like coatings and adhesives, electrical industries as circuit boards, semiconductors, aerospace and automobile applications, and the like Epoxies are thermosetting polymers having one or more three-membered epoxide or oxirane rings. The most important properties of these epoxy resins are their excellent electrical and mechanical properties with good chemical and corrosion resistance.
[0004] In spite of all these properties, they suffer from high flammability and brittleness. Many materials have been used till date to increase the toughness and flame retardancy of epoxy composites. Polymers like polyacrylonitrile (PANI), Acrylonitrile butadiene styrene (ABS), styrene butadiene styrene (SBS) and the like are the widely used tougheners for epoxy resin. Also, nanofillers like graphene oxide, carbon nanotubes, titanium dioxide, silicon dioxide, clay and the like are also found to enhance the thermo-mechanical properties of the epoxy resin. 2D materials like graphene and its derivatives are considered effective for epoxy toughening, hence 2D analogous materials like TMDs can also be considered as a better candidate for epoxy toughening.
[0005] Thermoplastics have also been reported as reinforcing fillers for epoxy resins. Recently, block copolymers are used as tougheners for epoxy matrix for improving its mechanical and thermal properties. Block copolymers (BCPs) possess the capability to form micelles, spheres, lamellae, and the like This property can be used for the exfoliation of TMDs like MoS2, and the like Nowadays, TMDs are gaining attention of researchers since they resemble the properties of graphene. There are many methods like thermal exfoliation, chemical exfoliation, atomic layer deposition, and the like for the exfoliation of TMDs. BCPs are also used for the exfoliation of bulk MoS2. BCP exfoliated TMDs are found to be effective in different applications like photocatalysis, sensors, transistors, and the like
[0006] Wei et al. developed a modest technique for the preparation of MoS2 nanoarrays using a BCP poly(styrene-b-2-vinylpyridine) via self-assembly. Nowadays, fiber-reinforced polymer composites (FRPCs) are utilized in many purposes due to their outstanding specific strength and stiffness, which enable effective toughening of the epoxy matrix.
[0007] Ma et al. developed a new fire retardant for epoxy resin based on amino pyrazine and,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The material showed better flame-retardant properties when analyzed by the cone calorimeter method and passed the vertical burning (UL-94) test with a V-0 rating.
[0008] Peng et al. proposed a sandwich-like structure containing pure epoxy and hollow glass beads (HGB/EP) as the syntactic foam composite, which was flame-treated. The compressive strength, thermal properties of the epoxy composites were examined, which showed an enhancement of about 33% in shear strength and 17.5% in compressive strength.
[0009] Shelly et al. reinforced epoxy-glass fiber composites with nano clay and polyethylene fiber via vacuum-assisted resin infusion molding (VARIM) process, which showed about 160% improvement in impact strength. Epoxy resin has several advantages like good flexibility, better thermo-mechanical properties and the like Despite all these properties, epoxies cannot be used in some applications where high-temperature performance is needed. So, efforts are being made to increase the thermo-mechanical properties of epoxy by the incorporation of different fillers. Now TMDs are studied as a better pick for toughening of epoxy but the studies involving TMDs and epoxy are still in its infancy.
[0010] The present inventors intend to develop a facile method for creating non-covalently bonded block copolymer modified TMDs as an effective nanofiller for toughening the polymer matrix to thermo-mechanical properties of the commercial epoxy utilizing the TBCP-TMDs as a new class of materials that can cause effective toughening in polymer composites.
[0011] Accordingly, the present disclosure provides a functionalized-TMD based toughening system for polymer composites, a polymer composite material comprising the same and photocatalytic methods of preparation thereof.
[0012] The present disclosure satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

OBJECTS OF THE INVENTION
[0013] Objects of the present disclosure are to provide an exfoliated-TMD based toughening system for polymer composites.
[0014] An object of the present disclosure is to provide a method of preparing the exfoliated-TMD based toughening system.
[0015] Another object of the present disclosure is to provide a TMD exfoliated with a tri-block copolymer (TBCP-exfoliated TMD).
[0016] Another object of the present disclosure is to provide a polymer composite reinforced with the TBCP-exfoliated TMD.
[0017] Yet another object of the present disclosure is to provide a method of preparing the epoxy composite reinforced with the TBCP-exfoliated TMD.
[0018] Yet another object of the present disclosure is to provide a finished product produced from the epoxy composite reinforced with the TBCP-exfoliated TMD.

SUMMARY OF THE INVENTION
[0019] This summary is provided to introduce a selection of concepts in a simplified form that is further described below in the detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0020] Aspects of the present disclosure relate to an exfoliated Transition Metal Dichalcogenides (TMDs) as a reinforcing agent for polymer composites. Specifically, the present disclosure relates to a TMD exfoliated with a tri-block copolymer (TBCP) and to a method of functionalizing the TMD with a tri-block copolymer. The present disclosure also relates to a composite polymer comprising the TBCP.
[0021] In a preferred aspect, the TBCP is Polyethylene glycol-b-Polypropylene Glycol-b-Polyethylene Glycol (PEG-PPG-PEG).
[0022] In a preferred aspect, the TMD is selected from molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2). Preferably, MoS2.
[0023] In another aspect, the present disclosure provides a method of preparing the TBCP-exfoliated TMD as disclosed herein, comprising the steps of:
a) dispersing TMDs in water via ultrasonication to obtain TMD solution; and
b) dispersing the TBCP in the TMD solution to obtain an exfoliation mixture,
c) exfoliating the TMD in the exfoliation mixture via ultrasonication for 15-30 min to obtain exfoliated-TMD, and
d) subsequently exfoliating the -TMD by stirring the mixture for 24 hrs to obtain TMD exfoliated with the TBCP (TBCP-exfoliated TMD).
[0024] In an aspect of the present disclosure, the ultrasonication is effected for 15-30 min.
[0025] In an aspect of the present disclosure, the ratio of the TMD:TBCP in water is 1:2.
[0026] In an aspect, the present disclosure provides a TBCP (PEG-PPG-PEG) exfoliated MoS2-based polymer composite, wherein the polymer composite is selected from but not limited to a fluoropolymer, a urethane polymer, a sulfonic polymer, an epoxy polymer, and mixtures thereof.
[0027] In yet another, the present disclosure provides a method of preparing the TBCP-exfoliated TMD-based epoxy composites, comprising the steps of:
a) providing the TBCP-exfoliated TMD, followed by dispersing the same in ethanol;
b) providing an epoxy monomer resin matrix;
c) adding the uniformly dispersed solution of TBCP-exfoliated TMD from step a) to the epoxy monomer resin matrix of step b) to obtain a mixture, followed by solvent removal via desiccation and heating the same to 70-90 ºC;
d) adding a curative agent (hardener) to the mixture from step c) to obtain the TBCP-exfoliated TMD-based epoxy composite.
[0028] In an aspect of the present disclosure, the ratio of epoxy monomer resin and the curative agent (hardener) is 1:0.244, respectively.
[0029] In an embodiment of the present disclosure, the amount of TBCP (PEG-PPG-PEG) exfoliated MoS2 is 0.01 to 1.0% w/w with respect to the total weight.
[0030] In a further aspect of the present disclosure, the method further comprises the step of pouring the PEG-PPG-PEG exfoliated MoS2/epoxy resin composite into moulds, followed by curing the same using hot air oven with pre-curing at 60-150 °C for 2 h and kept at a temperature of 160-200 °C for duration of 2 h for post-curing.
[0031] In still another aspect, the present disclosure provides a finished product comprising the PEG-PPG-PEG exfoliated MoS2 filler prepared by the method as disclosed herein.
[0032] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 relates to the schematic representation of preparing Epoxy Composites comprising the TBCP exfoliated MoS2-based epoxy composites.
[0034] FIG. 2 relates to the FTIR spectrum of MoS2 and TBCP exfoliated MoS2-based epoxy composites (MoS2/TBCP).
[0035] FIG. 3 relates to the Raman Spectra of MoS2, and MoS2/TBCP
[0036] FIG. 4 relates to the XRD of MoS2/TBCP.
[0037] FIG. 5 relates to the FESEM image of A. MoS2 B. MoS2/TBCP
[0038] FIG. 6 relates to the Polarized optical image of A and B) Pure MoS2 in ethanol and epoxy (C and D) MoS2/TBCP in ethanol and epoxy
[0039] FIG. 7 relates to the A) Fracture toughness and B) Tensile strength of EP, M0.1EP, MB0.1EP samples.
[0040] FIG. 8 relates to the fracture surface of Epoxy composites a) Neat b) MB0.1EP.
[0041] FIG. 9 relates to the TEM images of A) Neat epoxy, B) M0.1EP, C. MB0.1EP samples.
[0042] FIG. 10 relates to the TGA of A) Neat epoxy, M0.1EP, MB0.1EP, and DTG curves of B) Neat epoxy, M0.1EP, MB0.1EP.
[0043] FIG. 11 relates to the Tan delta curve of (A) Neat epoxy, M0.1EP, and MB0.1EP (B) Storage modulus of Neat epoxy, M0.1EP, and MB0.1EP (C) Cole-Cole Plot of Neat epoxy, M0.1EP, MB0.1EP.
[0044] FIG. 12 relates to the DSC curves of neat epoxy, M0.1EP, and MB0.1EP

DETAILED DESCRIPTION OF THE INVENTION
[0045] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.
[0046] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0047] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0048] In some embodiments, numbers have been used for quantifying weight percentages, ratios, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0049] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0050] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0051] Unless the context requires otherwise, throughout the specification, which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0052] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0053] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0054] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.
[0055] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0056] It should also be appreciated that the present disclosure can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0057] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0058] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements a, b, and c, and a second embodiment comprises elements b and d, then the inventive subject matter is also considered to include other remaining combinations of a, b, c, or d, even if not explicitly disclosed.
[0059] Embodiments of the present disclosure relate to an exfoliated Transition Metal Dichalcogenides (TMDs) as a reinforcing agent for polymer composites. Specifically, the present disclosure relates to a TMD exfoliated with a tri-block copolymer (TBCP) and to a method of functionalizing the TMD with a tri-block copolymer. The present disclosure also relates to a composite polymer comprising the TBCP.
[0060] In an embodiment of the present disclosure, the TBCP contains Polyethylene Glycol (PEG) and polypropylene glycol (PPG) in a weight ratio of 20:70:20 (EG:PG:EG).
[0061] In a preferred embodiment, the TBCP is Polyethylene glycol-b-Polypropylene Glycol-b-Polyethylene Glycol (PEG-PPG-PEG). In some embodiments, the PEG may have a molecular weight of 200 to 8000, and the PPG may have a molecular weight of 400 to 10000 .
[0062] In an embodiment of the present disclosure, the TMD is selected from molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2). Preferably, MoS2.
[0063] In some embodiments of the present disclosure, the TBCP has an average molecular weight of approximately 5800 (number average).
[0064] In another embodiment, the present disclosure provides a method of preparing the TBCP-exfoliated TMD as disclosed herein, comprising the steps of:
a) dispersing TMDs in water via ultrasonication to obtain TMD solution; and
b) dispersing the TBCP in the TMD solution to obtain an exfoliation mixture,
c) exfoliating the TMD in the exfoliation mixture via ultrasonication for 15-30 min to obtain exfoliated-TMD, and
d) subsequently exfoliating the -TMD by stirring the mixture for 24 hrs to obtain TMD exfoliated with the TBCP (TBCP-exfoliated TMD).
[0065] In an embodiment of the present disclosure, the TMD may be a monolayer, a bilayer, a trilayer, and the like.
[0066] In an embodiment of the present disclosure, the ultrasonication is effected for 15-30 min. For example, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 min. Preferably, 20 min.
[0067] In an embodiment of the present disclosure, the ratio of the TMD:TBCP in water is 1 to 2:1 to 2. For example, 1:1, 1:2, 2:2, or 2:1. Preferably, 1:2.
[0068] In a preferred embodiment, the present disclosure provides a method of preparing the TBCP (PEG-PPG-PEG) exfoliated MoS2 as disclosed herein, comprising the steps of:
a) dispersing MoS2 in water via ultrasonication to obtain MoS2 solution; and
b) dispersing the PEG-PPG-PEG in the MoS2 solution to obtain an exfoliation mixture,
c) exfoliating the MoS2 in the exfoliation mixture via ultrasonication for 15-30 min to obtain exfoliated - MoS2, and
d) subsequently exfoliating the - MoS2 by stirring the mixture for 24 hrs to obtain MoS2 exfoliated with the PEG-PPG-PEG (PEG-PPG-PEG exfoliated MoS2).
[0069] In an embodiment of the present disclosure, the ultrasonication is effected for 15-30 min. For example, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 min. Preferably, 20 min.
[0070] In an embodiment of the present disclosure, the ratio of the MoS2:PEG-PPG-PEG in water is 1 to 2:1 to 2. For example, 1:1, 1:2, 2:2, or 2:1. Preferably, 1:2.
[0071] In an embodiment of the present disclosure, the PEG-PPG-PEG exfoliated MoS2 may be used as a filler for polymer composites. In an embodiment, the present disclosure provides a TBCP (PEG-PPG-PEG) exfoliated MoS2-based polymer composite.
[0072] In some embodiments, the PEG-PPG-PEG exfoliated MoS2, in a concentration-dependent manner, improves fracture toughness of a polymer composite by 319% to 483%, compared to corresponding toughened-neat polymer.
[0073] In an embodiment of the present disclosure, the polymer composite is selected from but not limited to a fluoropolymer, a urethane polymer, a sulfonic polymer, an epoxy polymer, and mixtures thereof. Preferably, epoxy composite prepared from epoxy resin monomers.
[0074] In an embodiment, the present disclosure provides a method of preparing the TBCP-exfoliated TMD-based epoxy composites, comprising the steps of:
e) providing the TBCP-exfoliated TMD, followed by dispersing the same in ethanol;
f) providing an epoxy monomer resin matrix;
g) adding the uniformly dispersed solution of TBCP-exfoliated TMD from step a) to the epoxy monomer resin matrix of step b) to obtain a mixture, followed by solvent removal via desiccation and heating the same to 70-90 ºC;
h) adding a curative agent (hardener) to the mixture from step c) to obtain the TBCP-exfoliated TMD-based epoxy composite.
[0075] In an embodiment, the present disclosure provides a method of preparing the TBCP (PEG-PPG-PEG) exfoliated MoS2-based epoxy composites, comprises the steps of:
a) providing PEG-PPG-PEG exfoliated MoS2, followed by dispersing the same in ethanol;
b) providing an epoxy monomer resin matrix;
c) adding the uniformly dispersed solution of PEG-PPG-PEG exfoliated MoS2 from step a) to the epoxy monomer resin matrix of step b) to obtain a mixture, followed by solvent removal via desiccation and heating the same to 70-90 ºC;
d) adding a curative agent (hardener) to the mixture from step c) to obtain the TBCP (PEG-PPG-PEG) exfoliated MoS2-based epoxy composites.
[0076] In an embodiment of the present disclosure, the epoxy monomer resin is selected from but not limited to Diglycidyl Ether of Bisphenol A (DGEBA)-based epoxy resin, diglycidyl ether of bisphenol-A, diglycidyl ether of bisphenol-F, epoxy novolac resin, or a combination thereof.
[0077] In an embodiment of the present disclosure, the curative agent (hardener) is selected from but not limited to Diethylene Toluene diamine (DETDA), aromatic polyamine, and having at least one substituent on the same, which is selected from an aliphatic substituent, at an ortho position with respect to an amino group.
[0078] In an embodiment of the present disclosure, the ratio of epoxy monomer resin and the curative agent (hardener) is 1:0.1 to 0.1:1, respectively. Preferably, the ratio of epoxy monomer resin and the curative agent (hardener) is 1:0.244, respectively.
[0079] In an embodiment of the present disclosure, the amount of TBCP (PEG-PPG-PEG) exfoliated MoS2 is 0.01 to 1.0% w/w with respect to the total weight. For example, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1.0 wt% with respect to the weight of epoxy monomer resin. Preferably, 0.01 to 0.50 wt% with respect to the total weight.
[0080] In an embodiment of the present disclosure, the method further comprises the step of pouring the PEG-PPG-PEG exfoliated MoS2/epoxy resin composite into moulds, followed by curing the same using hot air oven with pre-curing at 60-150 °C for 2 h and kept at a temperature of 160-200 °C for duration of 2 h for post-curing.
[0081] In an embodiment, the present disclosure provides a finished product comprising the PEG-PPG-PEG exfoliated MoS2 filler prepared by the method as disclosed herein.
[0082] In an embodiment, the present disclosure provides a finished product comprising the PEG-PPG-PEG exfoliated MoS2 may be used in laminated circuit boards, electronic component encapsulations, surface coatings, adhesives, furniture, aerospace components, automotive industries, as protective coatings (anti-corrosive), furniture, antimicrobial coatings or materials and for biomedical applications.
[0083] While the foregoing description discloses various embodiments of the disclosure, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
EXAMPLES
[0084] The present disclosure is further explained in the form of following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
Materials:
MoS2 powder, PEG-PPG-PEG tri-block copolymer, Epoxy (DGEBA) and Curing agent Diethyl toluene diamine (DETDA).
[0085] Example 1: Synthesis of TBCP exfoliated MoS2
Approximately 100mg of MoS2 was weighed and dissolved in 15 ml of deionized water via ultrasonication for 20 minutes. To the TMD solution, 200mg of the block copolymer PEG-PPG-PEG was weighed and added. The resultant solution was ultrasonicated for 30 minutes and subjected to stirring for 24 hours to obtain the TBCP exfoliated MoS2. The excess block co-polymer was removed by washing using water and dried in acetone to yield TBCP-exfoliated MoS2.
[0086] Example 2: Synthesis of TBCP-exfoliated MoS2 Epoxy Composites
Epoxy composites with TBCP-exfoliated MoS2 as fillers was fabricated by dispersion of the fillers in ethanol via sonication and adding it into the epoxy matrix. After solvent removal by using vacuum desiccator, DETDA, curing agent was added into the mixture at 80°C in the ratio of 100:24.4. Then the mix was transferred to a pre-heated Teflon mold after vacuum degassing and precured and post-cured at a temperature of 140°C and 200°C for 2 hours respectively in a hot air oven. The TMDs-based epoxy composites with different weight percentages are denoted as Mo0.1EP, Mo0.3EP and Mo0.5EP. Similarly, TBCP exfoliated MoS2-based epoxy composite is denoted as MoB0.1EP respectively. FIG. 1 represents the exfoliation of MoS2 using TBCP and fabrication of TBCP exfoliated MoS2-based epoxy composites.
[0087] Example 3: Characterization Techniques
To analyze the intercalation of polymers inside the bulk TMD materials, Fourier transform infrared technique (Shimadzu, IR Prestige 21) from 4000 cm-1 to 500 cm-1 wavenumber range in ATR mode, Confocal Raman spectroscopic analysis (WITec GmbH, Ulm, Germany, Alpha300RA, AFM & RAMAN) and X-ray diffraction (Bruker D8 Advance) was employed. To confirm the exfoliation and analyze the morphology of TMDs by TBCP, Field Emission Scanning Microscopy (TESCAN BRONO s.r.o.Czech, MAIA3 XMH) was done. The morphological analysis of fracture surfaces of neat epoxy, pure TMDs toughened epoxy and TBCP exfoliated TMDs toughened epoxy were detected using Scanning Electron Microscope (SEM) (TESCAN VEGA3 SB). Also, to analyze the dispersion of the filler in the epoxy matrix, phase contrast microscopy (CX41 Olympus Phase contrast Trinocular microscope) was employed. Tensile strength, tensile modulus, and the elongation of break of the fabricated epoxy composites of dog-bone shaped samples with dimensions 165*12.7*3.2 mm3 were examined using UTM (Instron 5984, Instron, USA- ASTM standard D638) at 1 mm/min testing speed and gauge length of 100mm. The fracture toughness of the samples with dimension of 50 mm × 10 mm × 5 mm with single edge notch was analyzed using UTM (Instron 5984, USA) at crosshead speed 10mm/min (ASTM standard D5045). Five specimens of each epoxy composite for mechanical testing were prepared using a Teflon mold fabricated as per the dimensions. Thermal studies (SDT Q600, TA instruments) were carried out at a temperature range of 30 to 700ºC and a heating rate of 100 per minute in a nitrogen atmosphere. Differential Scanning Calorimetry (TA Instruments Germany) of the samples was done at a temperature from 30 and 250ºC at heating rate of 10ºC/ min in a nitrogen atmosphere. Dynamic Mechanical Analysis, Tritec 2000 DMA (Triton Technology, UK) of the epoxy sample was done at 1 Hz frequency from 300 C to 2500 C at heating rate of 20 C/min Stress intensity factor (KIC) was calculated by following Eq. (1), for expressing the fracture toughness.
eq. (1)
Where,

f(x) = 6x0.5 [1.99 – x(1 − x) 2.15 − 3.93x − 2.7x2 ] eq. (2)
(1 + 2x) (1 − x)1.5
Where B, L, W and a represents specimen thickness, the load at the initiation of crack, specimen width and length of crack respectively. Also, X denotes ratio of crack length to width.
Fourier Transform Infrared Spectroscopy (FTIR):
FTIR analysis was done to confirm the exfoliation of MoS2 bulk material into few-layered sheets by using TBCP as an exfoliating agent. The FTIR spectrum of MoS2, and MoS2/TBCP is shown in FIG. 2. FTIR shows the characteristic peaks at 645 and 667 cm-1 corresponding to W-S bonds. FTIR spectrum of TBCP shows a weak broad peak found at 3544 cm−1 corresponding to –OH group and the absorption bands observed at 2871 cm−1, 1078 cm−1 and 1104 cm−1, which corresponds to –OH, –CH and –CO stretching vibrations respectively. Also, the occurrence of a peak at 2871 cm−1 and 1104 cm−1 in the case of TBCP exfoliated MoS2, confirm the presence of TBCP in the MoS2. There is no proof of new bond formation between MoS2 and TBCP, indicating a non-covalent interaction with the exfoliating agent and the MoS2.
Raman Spectroscopy:
Raman spectroscopy was further used to confirm the exfoliation and intercalation of TBCP-exfoliated TMDs. FIG. 3 displays the Raman Spectra of MoS2 and MoS2/TBCP. In the case of bulk MoS2, it exhibits two Raman peaks at 377.8 and 404.2 cm-1 representing to the in-plane E12g and out-plane A1g respectively. For the MoS2/TBCP, the same peaks showed a shift and showed at 375.8 cm-1 and 400.9 cm-1. This shift can be allotted to the interaction between MoS2 and TBCP, where stress acts on the bond between Mo – S atoms and S – S atoms, which confirms the exfoliation of MoS2 sheets into a few layers using TBCP. Δꞷ can be used for finding the thickness of the TMDs and as per the literature the Δꞷ value should decrease after the exfoliation.In the case of MoS2, Δꞷ for bulk material is found to be 26.4, which shows a thick layered structure, and after exfoliation, it decreases to 25.1, which means exfoliation has taken place. During the exfoliation, peaks become closer as observed in literature. Thus, the exfoliating efficiency of TBCP can be confirmed from the Raman analysis, so TBCP can be considered as a good exfoliating agent owing to its amphiphilic characteristics.
X-Ray Diffraction Pattern:
FIG. 4 shows XRD pattern of MoS2 and MoS2/TBCP. The XRD of the materials shows highly crystalline phase with planes (002), (004), (100), (103) etc corresponding to the peaks 14.5, 32.8, 39.6 and 58.4 in the case of MoS2. Once the TMDs are exfoliated , the polymer chains of TBCP interact with the nanosheets and thus the crystallinity decreases. Thus, the d-spacing slightly increases confirming the exfoliation process and rules out the possibility of excessive polymer intercalation between the layers. In both the cases, it is found that the intensity of the (002) plane has decreased, which shows a disruption in the ordered structure of TMDs after exfoliation. So, from the results, it can be confirmed that exfoliation of TMDs has taken place into few layered structures.
Field Emission Scanning Electron Microscopy (FESEM)
FIG. 5 represents FESEM images of pure TMDs and the TBCP exfoliated TMDs. From the FESEM images of pure TMDs and the TBCP exfoliated TMDs, it is clear that for both cases, the size and thickness of the layers decreased after modification with TBCP when compared with the bulk material, which confirms that the bulk MoS2 has been exfoliated into few layers. FESEM images also prove that the number of layered particles has correspondingly increased after exfoliation, which proves the exfoliation process has taken place. The exfoliation process affects the surface of the 2D materials, from the SEM images it is clear that the unexfoliated TMDs have a smooth appearance, whereas after the exfoliation the surface become rough indicating the surface modification. TBCPs gets entangled in between the layers of TMDs, which leads to exfoliation.
Polarized Optical Microscopy
To analyze the distribution of TMDs in the epoxy matrix, we have dispersed the Pure TMDs and TBCP exfoliated TMDs in the same organic solvent used for fabricating the epoxy composites and in the epoxy matrix and taken the polarized optical images of the same. The polarized optical microscopic images of the dispersed filler, ie. Pure MoS2, and MoS2/TBCP in organic solvent and epoxy matrix are shown in FIG. 6 (A-D). From the optical microscopic image, it is clear that as TMDs get exfoliated with the TBCP, both the TMDs show better dispersion in the desired solvent indicative of the exfoliation-enhanced interaction with the organic solvent due to the presence of the TBCP in the modified TMDs. It is clear that MoS2 shows better dispersion in the solvent, which can be responsible for the enhanced mechanical strength of epoxy.
[0088] Example 5: Mechanical Properties:
Fracture Toughness
The fracture toughness as well as the tensile strength of the epoxy composites with different weight ratios of TMDs ranging from 0.05wt% to 0.5wt%, which showed 0.1 wt% to be the optimum filler ratio for better mechanical performance. In the case of TMDs toughened epoxy at lower loadings up to 0.1wt% the toughness increases linearly. But after the addition of 0.3wt% and 0.5wt%, the fracture toughness decreases, which can be attributed to the agglomeration or restacking of the TMDs in the epoxy matrix. The literature studies show that fracture toughness rises with a rise in filler content, but after some weight percentage, agglomeration of the filler causes a reduction in the KIC value.
So, in order to avoid the agglomeration and restacking of the TMDs, the effect of polymeric exfoliating agents like PVP, PEG, TBCP, and the like is of great importance. Hence, here in the study, we have utilized the same loading of TBCP exfoliated -based epoxy composites for comparison purposes. 0.1wt% of MoS2 showed 319% improvement in toughness compared to neat epoxy which is shown in FIG. 7A. The uniform distribution obtained at lower loading offers better filler- matrix interaction and thereby improve the fracture toughness as well as tensile strength of the epoxy composites. But, on further increase of the filler loading, agglomeration starts leading to lower distribution of the filler in the matrix and thereby decreasing the mechanical properties, which is evident form the results obtained.
It is observed that after the addition of TBCP exfoliated TMDs in the epoxy matrix, a well pronounced improvement is observed in the fracture toughness values. TBCP effectively works as a good exfoliating agent in both the TMDs and helps in enhancing the mechanical properties. This can be ascribed to the ability of TBCP in creating a better distribution of the TMDs in epoxy matrix, Recent studies on effect of TBCP in epoxy matrix, indicate that TBCPs are capable of improving the toughness of epoxy but the Tg and tensile properties will get negatively affected by it. Similarly, TMDs agglomerate at higher loadings. The modification of TMDs by TBCP will nullify the negative effects of both and a synergistic effect of both TBCP and TMDs will be witnessed. In case of TBCP exfoliated MoS2 (MoB0.1EP) KIC value is found to be 10.46 ± 0.7 MPaM1/2, which is about 483% compared to the neat epoxy. It is clear that in addition to the exfoliation effect of TBCP, the long polymeric chain is capable of interacting with the epoxy chains and enhances further cross-linking, which also helps in enhancing the toughness of epoxy. Since TBCP is good in exfoliating MoS2 to a greater extent than the MoS2-TBCP shows better compatibility with epoxy matrix and enhance the toughness.
Table 1: Fracture toughness and tensile strength values of TBCP exfoliated -based epoxy composites.
System Fracture Toughness
MPaM1/2 Tensile Strength
MPa
Neat 1.425 ±0.7 40±0.7
M0.1EP 5.975±0.4 36.8±0.07

MB0.1EP 8.3244±0.7 40.833±0.7

Mechanism of epoxy toughening
SEM images of the fractured surface were used to study the toughening of composites and is shown in FIG. 8. From the fractured surface of neat epoxy (FIG. 8A) the planar surface shows the brittleness of neat epoxy. But after the inclusion of TBCP modified TMDs, there is a pronounced enhancement in toughness, which can be attributed due to particle pullout along with formation of the microcracks as seen in FIG. 8B.
Tensile Strength
From our previous research, 0.1wt% was found to be the optimum filler ratio for better mechanical properties, because upon a further addition in filler- ratio leads to agglomeration of the TMDs that indeed decreases the mechanical properties. Tensile strength of pure TMD toughened epoxy composites and TBCP exfoliated TMD toughened epoxy composites is given below in FIG. 7B. Since, TMDs are expected to have some particulate nature in reinforcing the epoxy matrix, tensile strength decreases upon filler content due to restacking of the layers.
But, treating the TMDs with TBCP enhances better exfoliation and avoids restacking due to Vander Waal’s forces. So, for both cases, the TBCP exfoliated MoS2 shows better enhancement in fracture toughness and tensile strength when compared to the bare filler of the same weight ratio that is 0.1%. So similar to our previous study, it can be confirmed that the TBCP modification of 2D materials helps in enhancing the toughness without losing the tensile strength. Thus, the drawback of TBCP and 2D materials i.e the reduction of tensile strength and the agglomeration at higher loadings respectively can be nullified by the modification of 2D materials with TBCP. The tensile strength of MB0.1EP was found to be 40.83±0.7 MPa.
Table 2 represents the comparison of fracture toughness with existing TBCP toughened epoxy systems.
Table 2: Comparison of fracture toughness with existing TBCP toughened epoxy systems.
Block copolymer in epoxy Improvement in Fracture Toughness
% Filler Weight Ratio References
rGO/PCL-PPC-PCL 60% 30 wt% Y. Liu et al., Compos. Sci. Technol. 125 (2016) 108–113.
GO-g-PEG-PPG-PEG 400% 0.5 wt% J.S. Jayan, et al., Mater. Chem. Phys. (2020) 122930
MWCNT-g-TBCP 367% 0.1wt% J.S. Jayan, et al., ACS Appl. Eng. Mater. (2023)
MoS2 quantum dots/Epoxy 68% 0.1 wt% S. Riaz et al., Compos. Part A Appl. Sci. Manuf. 146 (2021) 106419.
WS2-Melamine/Epoxy 55% 0.18 wt% S. Riaz et al., Macromol. Res. 28 (2020) 1116–1126
MB0.1EP 483% 0.1 wt% Present Work

Transmission Electron Microscopy
TEM images of the neat epoxy, M0.1EP, MB0.1EP samples are shown in FIG. 9 (A-C). The HRTEM analysis helps in analyzing the exfoliation process of TMDs and the dispersion of TBCP-exfoliated TMDs in the epoxy matrix. The block copolymers tend to form micellar structures in the epoxy matrix, which further improves the mechanical properties. From the HRTEM images of pure TMDs toughened epoxy composites, sheet-like structures that are effectively exfoliated and well distributed in the epoxy matrix can be identified. Whereas in the case of TBCP exfoliated TMDs, the inherent capability of TBCPs in forming micellar nanostructures enables even more uniform distribution of the filler. In the case of the MB0.1EP system, the spherical micelles formed are found efficient in increasing the mechanical properties of the epoxy.
[0089] Example 6: Thermal Properties:
Thermogravimetric Analysis
TGA curves of EP, M0.1EP, MB0.1EP are shown in FIG. 10A. From the figure it is clear that the addition of M0.1EP, MB0.1EP do not have much effect on the thermal stability of epoxy. The degradation temperature of neat epoxy, M0.1EP, MB0.1EP was found to be 3400 C,3400 C and 3300 C respectively. The char yield of M0.1EP, MB0.1EP was 12.18% and 11.09%, whereas for neat epoxy it was 9.82% indicating the presence of non-combustible materials. Also, From the first derivative graph shown in 10B, in the case of neat epoxy, M0.1EP, MB0.1EPtoughened epoxy systems shows one stage degradation irrespective of the filler used. The peak temperature for EP, M0.1EP, MB0.1EP were obtained as 390, 370, and 3800 C, respectively.

Dynamic Mechanical Analysis
Tan  from the DMA analysis is used to figure out the damping factor, which denotes the elastic or the viscous properties of a particular system whose peak height represents internal energy dissipation at matrix/filler interphase. FIGs. 11A and 11B shows the tan delta curve and storage modulus of neat epoxy, M0.1EP, MB0.1EP. From the tan delta curve, the glass transition temperature, Tg of neat epoxy, M0.1EP, MB0.1EP, W0.1EP, and WB0.1EP was found as 1880C, 1760C, 1230C, 1960C, and 1790C respectively. The Tg value decreases after the addition of M0.1EP and decreases upon the addition of MB0.1EP. This can be attributed to the plasticizing nature of TBCP, which is considered as its inherent drawback. Even though the Tg value is reducing it is not negatively affecting the mechanical properties of epoxy due to the well exfoliation of TMDs via TBCP. But still, the plasticizing effect of TBCP causes a reduction in the Tg value. However, as per literature studies, a grafted filler could increase the Tg value and improve the mechanical properties. From the storage modulus graphs it is evident that the incorporation of TMDs like MoS2 enhances the storage modulus, whereas the incorporation of TBCP leads to a reduction in storage modulus owing to its plasticizing effect.
In our previous study, the Tg value was unaffected by the functionalization of TBCP with graphene oxide owing to the covalent interaction between them. But in this case, there is no covalent interaction between TMDs and TBCP, hence the Tg value is negatively affected by the addition of TBCP. Nevertheless, the mechanical properties are not disturbed by the incorporation of TBCP-modified TMDs, which could be attributed to the self-assembly nature of the TBCP.
Also, from the tan delta curves, the damping characteristics can be identified which shows that in the case of M0.1EP and MB0.1EP even though there is a decrease in the Tg value after the incorporation of MB0.1EP, the intensity of the peaks have increased after exfoliation. The increased intensity corresponds to the increase in the damping characteristics. The presence of TBCP-modified TMDs helps in an enhancement in the damping characteristics.
Owing to the interest in analyzing the miscibility of the fillers in epoxy matrix, the Cole-Cole plot is drawn and, which is shown in FIG. 11C. From the graph it is evident that the prepared fillers are miscible in epoxy matrix. The semi-circle shape of the curves ensures the miscibility of fillers in epoxy matrix, which leads to enhanced mechanical properties. The better miscibility of filler in matrix ensures improved mechanical properties.
Differential Scanning Calorimetry
FIG. 12 shows the DSC curves of EP, M0.1EP, MB0.1EP respectively. From the DSC curves, the Tg value of epoxy composites are calculated. For EP, M0.1EP, and MB0.1EP the Tg values are 1500C, 155 0C, and 1500C, respectively. The results from DMA and DSC follow the same trend, as upon the incorporation of TBCP there is a decrease in Tg value due to the inherent plasticizing nature of TBCP. Thus, the TBCP-exfoliated TMDs show a decrease in Tg after the incorporation of TBCP.
, Claims:1. A transition metal dichalcogenide (TMD) exfoliated with a tri-block copolymer (TBCP-exfoliated TMD), wherein the TBCP contains Polyethylene Glycol and polypropylene glycol in a weight ratio of 20:70:20 for EG:PG:EG, respectively and wherein the TMD is selected from molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2).

2. The TBCP-exfoliated TMD as claimed in claim 1, wherein the TBCP has an average molecular weight of approximately 5800.

3. The TBCP-exfoliated TMD as claimed in claim 1, wherein the TBCP is Polyethylene glycol-b-Polypropylene Glycol-b-Polyethylene Glycol (PEG-PPG-PEG).

4. A method for preparing the TBCP-exfoliated TMD as claimed in anyone of claims 1 to 4, comprising
a) dispersing TMDs in water via ultrasonication for 20 min to obtain TMD solution; and
b) dispersing the TBCP in the TMD solution to obtain an exfoliation mixture,
c) exfoliating the TMD in the exfoliation mixture via ultrasonication for 20 min to obtain exfoliated-TMD, and
d) subsequently exfoliating the -TMD by stirring the mixture for 24 hrs to obtain TMD exfoliated with the TBCP (TBCP-exfoliated TMD).

5. The method as claimed in claim 1, wherein the ratio of the TMD:TBCP in water is 1:2.

6. A filler for a polymer composite comprising the TBCP-exfoliated TMD as claimed in anyone of claims 1 to 5.

7. A polymer composite comprising the filler as claimed in claim 7, wherein the polymer composite is selected from a fluoropolymer, a urethane polymer, a sulfonic polymer, an epoxy polymer, and mixtures thereof, and wherein the polymer composite comprises 0.1 to 1% w/w of the filler, based on the total weight.

8. The polymer composite as claimed in claim 9, wherein the filler enhances the toughness of the polymer composite by 319% to 483%, compared to corresponding neat polymer.

9. A method of preparing the TBCP-exfoliated TMD-based epoxy composites, comprising the steps of:
a) providing the TBCP-exfoliated TMD, followed by dispersing the same in ethanol;
b) providing an epoxy monomer resin matrix;
c) adding the uniformly dispersed solution of TBCP-exfoliated TMD from step a) to the epoxy monomer resin matrix of step b) to obtain a mixture, followed by solvent removal via desiccation and heating the same to 70-90 ºC; and
d) adding a curative agent (hardener) to the mixture from step c) to obtain the TBCP-exfoliated TMD-based epoxy composite.

10. The method as claimed in claim 10, wherein the curative agent (hardener) is selected from but not limited to Diethylene Toluene diamine (DETDA), aromatic polyamine, and having at least one substituent on the same, which is selected from an aliphatic substituent, at an ortho position with respect to an amino group.

11. The method as claimed in claim 10, wherein the ratio of epoxy monomer resin and the curative agent (hardener) is 1:0.244, respectively.

12. The method as claimed in claim 10, wherein the amount of TBCP-exfoliated TMD is 0.01 to 0.50 wt% with respect to the total weight.

13. The method as claimed in claim 10 further comprises the step of pouring the TBCP-exfoliated TMD-based epoxy composite into moulds, followed by curing the same using hot air oven with pre-curing at 60-150 °C for 2 h and post-curing the same at a temperature of 160-200 °C for duration of 2 h for post-curing.