BETA-CYCLODEXTRIN-BASED MONOLITHS THROUGH EMULSION TEMPLATING

Abstract

Provided herein is a porous β-cyclodextrin-containing monolith having a microstructure templated by the external phase of a HIPE, as well as processes of manufacturing the same and uses thereof.

Claims

1. A composition-of-matter comprising a polymer, wherein said polymer comprises a plurality of β-cyclodextrin residues, and having a microstructure that is templated by a polymerized high internal phase emulsion (HIPE).

2. The composition-of-matter of claim 1, wherein a content of said β-cyclodextrin residues in said polymer is at least 10 wt %.

3. The composition-of-matter of claim 1, characterized by having less than 10% urea residues.

4. The composition-of-matter of claim 3, essentially devoid of urea residues.

5. The composition-of-matter of claim 1, wherein said polymer further comprises residues of a polyisocyanate monomer.

6. The composition-of-matter of claim 3, wherein said polyisocyanate is a diisocyanate monomer.

7. The composition-of-matter of claim 6, wherein said diisocyanate monomer is selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate, toluene diisocyanate, methylene diphenyl diisocyanate, and any combination thereof.

8. The composition-of-matter of claim 1, wherein said polymer further comprises residues of a poloxamer.

9. The composition-of-matter of claim 8, wherein said poloxamer is Pluronic F-127.

10. The composition-of-matter of claim 1, characterized by at least one of: a density lower than 0.3 g/cc; a modulus of at least 0.3 MPa; and/or a compressive failure strain of at least 10%.

11. A process of preparing the composition-of-matter of claim 1, the process comprising: providing a first organic phase (a first solution) that comprises β-cyclodextrin and a polyisocyanate; mixing said first organic phase with a second organic phase that is immiscible with/in said first organic phase, and a surfactant/HIPE-stabilizer, thereby obtaining a HIPE; and polymerizing said HIPE, thereby obtaining the composition-of-matter.

12. The process of claim 11, wherein said surfactant/HIPE-stabilizer is selected from the group consisting of a poloxamer, polyglycerol polyricinoleate (PGPR), a plurality of star nanoparticles, and the like.

13. The process of claim 11, wherein said first organic phase and/or said second organic phase further comprises an initiator and/or a catalyst.

14. The process of claim 11, further comprising, subsequent to said polymerizing, subjecting the composition-of-matter to Soxhlet extraction.

15. The process of claim 11, further comprising, subsequent to said polymerizing, drying the composition-of-matter under ambient or reduced pressure and/or under ambient or elevated temperature.

16. An article of manufacturing comprising the composition-of-matter of claim 1.

17. The article of claim 16, selected from the group consisting of a spillage containment device, a pollution detection and prevention device, and an in-flow filter.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0034] Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

[0035] In the drawings:

[0036] FIG. 1 presents SEM micrographs at various magnification levels of the exemplary β-CD-polyHIPE prepared as described herein;

[0037] FIG. 2 presents FTIR spectra of β-CD (the building block, or monomer), F-127 (the surfactant/reactant), and an exemplary β-CD-polyHIPE prepared as described herein;

[0038] FIG. 3 presents a plot showing the compressive stress-strain curves of an exemplary β-CD-polyHIPE prepared as described herein; and

[0039] FIGS. 4A-B present UV adsorption curves, showing the amount of BPA decreasing in a 10 mL solution sample from 0.1 mM BPA, using 50 mg of the adsorbent β-CD-polyHIPE, according to some embodiments of the present invention, wherein FIG. 4A shows the UV-vis spectra of the solution at various time intervals, and FIG. 4B shows the percentage of BPA remaining in the solution, R.sub.BPA, as a function of time.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0040] The present invention, in some embodiments thereof, relates to material science, and more particularly, but not exclusively, to a porous monolith containing β-cyclodextrin.

[0041] The principles and operation of the present invention may be better understood with reference to the figures and accompanying descriptions.

[0042] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

[0043] This document discloses a novel β-CD-based polyHIPE (β-CD-polyHIPE), which was generated using a relatively rare approach, synthesis through a urethane step-growth reaction between the β-CD hydroxyl groups and an isocyanate in a non-aqueous, oil-in-oil (o/o) HIPE. The use of an o/o HIPE enables access to a relatively high loading of β-CD in the external phase, and at the same time, limits the competing urea-forming reaction of the isocyanate with water.

[0044] It is expected that during the life of a patent maturing from this application many relevant β-CD-polyHIPE monolith will be developed and the scope of the term β-CD-polyHIPE monolith is intended to include all such new technologies a priori.

[0045] As used herein the term “about” refers to ±10%.

[0046] The terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean “including but not limited to”.

[0047] The term “consisting of” means “including and limited to”.

[0048] The term “consisting essentially of” means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure. As used herein, the phrases “substantially devoid of” and/or “essentially devoid of” in the context of a certain substance, refer to a composition that is totally devoid of this substance or includes less than about 5, 1, 0.5 or 0.1 percent of the substance by total weight or volume of the composition. Alternatively, the phrases “substantially devoid of” and/or “essentially devoid of” in the context of a process, a method, a property or a characteristic, refer to a process, a composition, a structure or an article that is totally devoid of a certain process/method step, or a certain property or a certain characteristic, or a process/method wherein the certain process/method step is effected at less than about 5, 1, 0.5 or 0.1 percent compared to a given standard process/method, or property or a characteristic characterized by less than about 5, 1, 0.5 or 0.1 percent of the property or characteristic, compared to a given standard.

[0049] The term “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments.

[0050] The words “optionally” or “alternatively” are used herein to mean “is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of “optional” features unless such features conflict.

[0051] As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a compound” or “at least one compound” may include a plurality of compounds, including mixtures thereof.

[0052] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0053] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0054] As used herein the terms “process” and “method” refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, material, mechanical, computational and digital arts.

[0055] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0056] Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental and/or calculated support in the following examples.

EXAMPLES

[0057] Reference is now made to the following examples, which together with the above descriptions illustrate some embodiments of the invention in a non limiting fashion.

Example 1

βCD-based PolyHIPE Synthesis—Materials and Methods

[0058] Materials: β-CD, hexamethylene diisocyanate (HDI; shown below), Pluronic F-127 poloxamer (a triblock copolymer shown below and consisting of poly(ethylene oxide) (PEO) end blocks and a poly(propylene oxide) (PPO) midblock), n-hexadecane (n-HD), dibutyltin dilaurate (DBTDL; a catalyst for polyurethane production from isocyanates and diols), and BPA were purchased from Sigma-Aldrich. All the chemicals were used as received. Analytical grade dimethylformamide (DMF) was purchased from Bio-Lab Chemicals. The DMF was dried prior to use using activated molecular sieves (about 0.4 nm) that were purchased from Merck. Dichloromethane (DCM) and ether were purchased from Bio-Lab Chemicals and used as received.

##STR00001##

[0059] PolyHIPE Synthesis: Prior to use, the DMF was dried overnight using activated molecular sieves. The minor, external phase of the HIPE was a DMF solution of β-CD (monomer), HDI (monomer), and F-127 (surfactant). The major, internal phase of the HIPE was n-HD. The HIPE was formed by adding n-HD (oil phase 2; internal) to the DMF solution (oil phase 1; external) in three portions, mixing for 5 min at 3500 rpm using a SpeedMixer™ DAC-150.1 FVZ.K after each addition. After the final n-HD portion was mixed, the DBTDL catalyst was added and an additional 2 min mixing was applied. The HIPE was then placed for 24 hours in a convection oven at 65° C. to effect polymerization.

[0060] It is noted that an optional process includes adding vinyl groups to the β-cyclodextrin in one reaction and then use a radical or thiol-ene reaction to “polymerize” β-cyclodextrin.

[0061] The resulting β-CD-polyHIPE was purified through Soxhlet extraction, first with DCM and then with ether. The β-CD-polyHIPE was then dried overnight in a vacuum oven at room temperature. An exemplary HIPE recipe for β-CD-polyHIPE, according to some embodiments of the present invention, is presented in Table 1.

TABLE-US-00001 TABLE 1 Amount, wt % External Phase β-Cyclodextrin (β-CD) 4.18 Hexamethylene diisocyanate (HDI) 3.77 Pluronic F-127 2.09 Dimethylformamide (DMF) 14.64 Total 24.69 Internal Phase n-Hexadecane (n-HD) 75.31 Total 75.31 Dibutyltin dilaurate (DBTDL) 24 drops

[0062] Characterization: The molecular structure was characterized using Fourier transform infrared spectroscopy (Bruker Equinox 55 FTIR). The sample was ground together with KBr and pressed to pellets for the FTIR measurements. The resulting composition-of-matter (a monolithic highly porous structure) was observed using scanning electron microscopy (SEM, FEI E-SEM Quanta 200). The average void diameter was corrected by a factor that takes into account the random nature of the section through the sphere.

[0063] Compressive stress-strain measurements were performed on 5 mm×5 mm×5 mm cubes using an Instron 3345. The measurements were carried out at a strain rate of 10% per minute until a strain of 70% was reached. The static compressive modulus (E) was calculated from the linear slope of the stress-strain curve at low strains.

[0064] BPA Adsorption: Adsorption studies were performed using ultraviolet-visible (UV-vis) spectroscopy from 200 to 600 nm (Shimadzu UV-1800) at room temperature. The β-CD-polyHIPE adsorbent was cut into rectangular pieces (10 mm×10 mm×1 mm) of about 50 mg. To remove entrapped air, the pieces of adsorbent were placed into 20 ml scintillation vials and deionized water was added. The vials were placed in a vacuum oven at low vacuum until the adsorbent sank to the bottom of the vials (between 30 and 90 minutes). The amount of water that evaporated during the deaeration process was determined by mass loss and the amount that evaporated was replaced. The concentration of the working BPA solution, 0.1 mM, was achieved using a stock solution such that the 50 mg of sorbent was immersed in 10 mL of a 0.1 mM BPA solution. The concentration of BPA in the solution was followed as a function of time by removing a sample of the solution from the vial using a Pasteur pipette at various time intervals (the vials were only used for one concentration measurement). Any debris in the solution was removed by passing it through a pipette containing cotton. The relative concentration of BPA was determined using UV-vis spectroscopy based on a calibration curve at 276 nm. The fraction of BPA removed (R.sub.BPA) was determined using Equation 1:

[00001]$\begin{array}{cc}{R}_{BPA}=\frac{\left(C_0-C_t\right)}{C_0}& \mathrm{Equation}1\end{array}$

[0065] wherein C.sub.0 (mmol/L) and C.sub.t (mmol/L) are the initial and residual concentrations of the working solution and the solution samples taken at various time intervals, respectively.

Example 2

Results and Analysis

[0066] The resulting exemplary β-CD-polyHIPE was afforded as a white monolith with a relatively low density (0.11 g/cc) and with a uniform, highly porous structure (see, FIG. 1).

[0067] FIG. 1 presents SEM micrographs in various magnification levels of the exemplary β-CD-polyHIPE prepared as described herein.

[0068] As can be seen in FIG. 1, the composition-of-matter, according to some embodiments of the present invention, was afforded while being templated by the precursor HIPE, giving rise to a porous monolith.

[0069] FIG. 2 presents an FTIR spectra of β-CD (the building block, or monomer), F-127 (the surfactant/reactant), and an exemplary β-CD-polyHIPE prepared as described herein.

[0070] Urethane groups are generated through the reaction of HDI with the hydroxyl groups in β-CD and F-127, while urea groups can be generated through the reaction of HDI with any traces of water in the system and in the environment. As can be seen in FIG. 2, the absence of a band at 2270 cm.sup.−1 (NCO stretching) indicates the complete reaction of the HDI. The spectrum of β-CD-polyHIPE exhibits urea CNH stretching at 1575 cm.sup.−1 and pronounced urethane C═O stretching at 1714 cm.sup.−1. The broad band at around 3350 cm.sup.−1 that can be associated with NH stretching corresponds to both urethane and urea. The presence of symmetric and asymmetric stretches of CH.sub.2 at 2860 and 2930 cm.sup.−1, respectively, indicates that some F-127 was incorporated into the β-CD-polyHIPE macromolecular structure through reaction with the HDI. The FTIR spectra of both β-CD and β-CD-polyHIPE exhibit intense C-O stretching at 1030 cm.sup.−1 that is characteristic of β-CD.

[0071] FIG. 3 presents a plot showing the compressive stress-strain curves of an exemplary β-CD-polyHIPE prepared as described herein

[0072] As can be seen in FIG. 3, the compressive stress-strain curve of β-CD-polyHIPE is characteristic of elastomeric, open-cell foams with a linear stress-strain relationship at low strains that exhibits a modulus of 0.44 MPa, a decrease in the rate of stress increase with strain at intermediate strains, and a rapid increase in stress with strain at higher strains. The β-CD-polyHIPE, according to some embodiments of the present invention, did not fail up to compressive strains of 70%.

[0073] FIGS. 4A-B present UV adsorption curves, showing the amount of BPA decreasing in a 10 mL solution sample from 0.1 mM BPA, using 50 mg of the adsorbent β-CD-polyHIPE, according to some embodiments of the present invention, wherein FIG. 4A shows the UV-vis spectra of the solution at various time intervals, and FIG. 4B shows the percentage of BPA remaining in the solution, R.sub.BPA, as a function of time.

[0074] Additional adsorption tests using more solution and less adsorbent in the article have reached an equilibrium of 30.2 mg BPA per gram adsorbent and have demonstrated a BPA adsorption capacity of 74.6 mg/g.

[0075] As can be seen in FIGS. 4A-B, the adsorbent β-CD-polyHIPE, according to some embodiments of the present invention, removed 72% of the BPA from the 0.1 mM solution within the first 30 minutes and 90% of BPA were removed within the next 2.5 hours. The monolith maintained its shape during the experiment and was easily removed from the solution.

[0076] The demonstration of the basic concept of the present invention has been proven valid, as a highly porous monolith based on β-cyclodextrin (an exemplary embodiment of a composition-of-matter of the present invention) was synthesized successfully through a urethane step-growth reaction within an oil-in-oil high internal phase emulsion. The resulting β-CD-polyHIPE was a white monolith with a density of 0.11 g/cc and a modulus of 0.44 MPa that could undergo 70% compressive strain without failing. In addition, the β-CD-polyHIPE has been shown to successfully remove bisphenol A from an aqueous solution within a few hours.

Example 3

Crosslinking Fraction, Insoluble and Gel Contents

[0077] The insoluble content (IC), the insoluble fraction of the polymer, is, under certain circumstances, referred to as the gel content (GC) of the polymer, or the crosslinked fraction of the polymer.

[0078] The IC of the polymer provided herein is determined by extracting the polymer with a solvent that is known to dissolve the polymer (e.g., N,N-dimethylformamide, DMF). Specifically, samples of the dry polymer (m.sub.b) are placed in filter-paper envelopes and immersed in refluxed boiling solvent for 48 hours. The samples are removed, dried in a vacuum oven for 24 hours, and the resulting dry mass (m.sub.a) is determined, wherein the IC of the polymer is determined by the ratio of m.sub.a to m.sub.b.

[0079] In the context of the present disclosure, IC is used instead of GC when there may be urea groups that are hard to dissolve, even in a linear, non-crosslinked polymer.

[0080] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

[0081] It is the intent of the applicant(s) that all publications, patents and patent applications referred to in this specification are to be incorporated in their entirety by reference into the specification, as if each individual publication, patent or patent application was specifically and individually noted when referenced that it is to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.

[0082] To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.