New tethered plasticizer-like agents & uses thereof

Abstract

The invention relates to plasticizer-like agents useful in the preparation of self-plasticized PVC, plasticizer leak-free PVC-based polymers and methods of preparation and uses thereof. In particular, the invention relates to uses of the new self-plasticized PVC material as matrix for ion-selective electrodes notably advantageous for wearable or environmental sensors.

Description

[0001] NEW TETHERED PLASTICIZER-LIKE AGENTS & USES THEREOF

[0002] Field of the Invention

[0003] The present invention pertains generally to the field of self-plasticized poly(vinyl chloride) (PVC) material and uses thereof.

[0004] Background of the invention

[0005] Poly(vinyl chloride) (PVC) is a versatile material used in different industries such as construction, healthcare, electronics and daily consumer products. PVC can be manufactured as is or used in combination with so-called plasticizers that reduce the glass transition temperature of the polymer to make it softer and more malleable. Commonly used plasticizers fall in different families, such as phthalates (bis(2-ehtylhexyl) phthalate - DEHP), adipates (dioctyl adipate - DOA), sebacates (dioctyl sebacate - DOS) or trimellitates (trioctyl trimellitate - TOTM). It has been known for several decades that these plasticizers tend to migrate within the PVC matrix and eventually leach out, thus raising concerns for the environment, wildlife and humans (Erythropel et al., 2014, Applied Microbiology and Biotechnology, 2014, 98, 9967-9981; Kastner et al., 2012, Science of The Total Environment, 432, 357-364). This concern is especially critical in PVC-based medical devices, where plasticizers may leach directly into body fluids such as blood (Messori et al, 2004, Polymer, 45, 805-813; Latini et al., 2010, Current Medicinal Chemistry, 17, 2979-2989; Jaeger et al, 1970, Science, 170, 460-462).

[0006] Phthalate-based plasticizers, such as bis(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP) or diisodecyl phthalate (DIDP), have been under intense scrutiny due to their prevalent usage in medical devices, toys or food packaging6and their potential carcinogenicity and ability to act as endocrine disruptors (Tickner et al., 2001, Industrial Medicine, 2001, 39, 100- 111; Heudorf et al., 2007, International Journal of Hygiene and Environmental Health, 210, 623-634).

[0007] Due to these concerns, a special emphasis has been placed nowadays on finding solutions to counteract the leaching process and reduce environmental and health risks. Green plasticizers, such as cardanol from cashew nutshell liquid (Greco et al., 2010, Polymer Degradation and Stability, 95, 2169-2174), epoxidised vegetable oil (Hosney et al., 2018, Journal of Applied Polymer Science, 135, 46270) or curcumin derivatives (Saitos et al, 2014, RSC Advances, 4, 54725-54728) have been envisioned as an eco-friendly solution. Although these alternatives are attractive for environmental purposes, they still do not solve the leaching process and are therefore not ideal for medical or food grade PVC. Surface coating has also been successfully investigated to stop the leaching process of plasticizers (Messori et al., 2004, supra) but on the downside it increases the complexity and manufacturing price of the material. Other approaches include the use of polymeric plasticizers, such as rubber derived molecules (Sunny et al, 2004, Journal of Elastomers & Plastics, 36, 19-31) small branched plasticizer analogues (Halloran et al., 2021, Materials Today Communications, 29, 102874) or ionic liquids (Rahman et al, 2006, Polymer Degradation and Stability, 91, 3371-3382) and all showed good results in terms of slowing down the leaching process.

[0008] Alternatively, the chemical modification of PVC to generate more flexible polymers has been explored through different pathways, like crosslinking (Lakshmi et al., 1998, Polymer, 1998, 39, 151-157; Romero et al., 2006, European Polymer Journal, 2006, 42, 961-969; Ambrogi et al., 2012, Polymer Engineering & Science, 52, 211-217'). Although successful at reducing the leaching, this approach can be problematic as this procedure may alter the inherent properties of the polymer, rendering it in some cases more viscous or thermally unstable (Rosales-Jasso etal., 2000, Polymer Degradation and Stability, 68, 253-259).

[0009] Another approach that has proven fruitful is the covalent linkage of the plasticizer directly onto the PVC. This has been investigated by Navarro et al. in 2010 where they grafted a thiol modified version of DEHP to the PVC backbone in order to generate an internally plasticized polymer (Navarro et al, 2010, Macromolecules, 43, 2377-2381). Following a similar methodology, chlorine groups on PVC have been substituted to obtain azide groups, which are ideal to perform click chemistry. The modified polymer can then easily react with a plasticizerlike molecule bearing an alkyne group.

[0010] In depth research on the topic has been performed by Braslau and co-workers, where they took advantage of the triazole ring formation during the click reaction to generate phthalate analogues acting as plasticizer (Earla et al., 2014, Macromolecular Rapid Communications, 35, 666-671). Unfortunately, this approach did not lower the glass transition temperature of the polymer sufficiently to achieve flexible materials. In a follow-up piece of work, the same group investigated the use of carbon chain linkers to place the plasticizer-like moiety further away from the backbone as well as various ester moieties on the alkyne used to form the triazole ring. With this approach, they generated a wide variety of polymers with glass transition temperatures ranging from 96°C to -42°C and managed to avoid plasticizer leaching (Higa et al., 2018, Journal of Polymer Science Part A: Polymer Chemistry, 56, 2397-2411). Using a similar methodology, Ma and Chu synthesised an internally plasticized PVC with a castor oil derivative (Chu et al., 2018, Korean Journal of Chemical Engineering, 35, 2296-2302).

[0011] For decades now, ion-selective membranes have been based on PVC and plasticizers are routinely added to generate soft and flexible membranes with a desirable diffusion coefficient. In this case as well, leaching of membrane components, such as ion-exchanger (Paczosa-Bator et al., 2010, Taianta, 81, 1003-1009; Telting-Diaz et al., 2001, Anal Chem, 73, 5582-5589), ionophore (M. a. de los A. Arada et al., 2003, Sensors and Actuators B: Chemical, 89, 262- 268) or plasticizer (Dinten, et al., 1991, Anal Chem, 1991, 63, 596-603; Oesch et al., 1980, Anal Chem, 52, 692-700) has been thoroughly studied.

[0012] It is well established in the field that the limited lifetime of ion-selective membranes is mainly due to this leaching process (Bakker et al., 1997, Chemical Reviews, 97, 3083-3132). This eventually leads to loss of selectivity, sensitivity and can even raise concerns of cytotoxicity especially for sensors designed for in vivo analysis. Cosofret et al. already demonstrated in 1994 that plasticizer diffusing out of the membrane was inducing an increase in total leukocytes, resulting in a potential inflammatory response Cosofret et al., 1994, Analytical Letters, 1994, 27, 3039-3063; Lindner et al, 1995, Electroanalysis, 7, 864-870).

[0013] These early findings were later supported by studies performed on mouse cell lines (Eljezi et al. 2017, Chemosphere, 173, 452-459; Chaves et al., 2010, , Dental Materials, 2010, 26, 1017- 1023) or human cell lines Savva et al., 2023, Chemosphere, 313, 137494). Strategies to prevent the leaching of membrane components have been investigated and one prevalent route was the use of a methacrylate-type or methacrylic-acrylic-type copolymer. During the synthesis of the copolymer, the amount of each monomer can be adjusted to give rise to a matrix with a sub-zero glass transition temperature, requiring no additional plasticizer (Qin et al., 2002, Electroanalysis, 14, 1375-1381).

[0014] Photocuring was used in most cases to generate the copolymer and because of this simple procedure, ionophores were also successfully attached to the matrix, thus increasing the stability of the system (Heng et al, 2000, Anal Chem, 2000, 72, 42-51 ; Heng et al, 2000, Electroanalysis, 2000, 12, 178-186; Qin et al., 2003, Anal Chem, 275, 3038-3045; Malino ska et al., 2000, Analytica Chimica Acta, 2000, 421, 93-101; Qin et al., 2004, Anal Chem, 76, 4379-4386).

[0015] In some cases, the approach suffers from limited reproducibility because small experimental variations can alter the resulting polymer properties. Moreover, light curing may promote the degradation of sufficiently reactive membrane components. Using this approach, Qin and Bakker presented an example in 2003 where a dodecacarborane anion was covalently attached to the methyl methacrylate - decyl methacrylate matrix, acting as cation-exchanger (Qin and Bakker, 2003, Anal Chem, 275, 6002-60 JO).

[0016] More recently, Biihlmann and co-workers developed a pH-selective electrode based on copolymerised membrane with either the cation-exchanger or the ionophore attached to it (Choi et al., 2021, Anal Chem, 93, 16899-16905).

[0017] This system was unfortunately not functional if both membrane components were covalently attached. This approach was also extended to optical sensors, so-called optodes, where the copolymer was used as simple matrix (Peper et al, 2003, Analytica Chimica Acta, 500, 127- 136) or even with the chromoionophore covalently attached to it (Ngeontae et al., 2007, Analytica Chimica Acta, 599, 124-133). The later example did show some shortcomings of the self-plasticized poly(w-butyl acrylate) matrix as co-polymerisation of the / / -butyl acrylate monomer and modified chromoionophore resulted in non-functional sensors.

[0018] Although giving promising results, this approach deviates from classical ion-selective membranes, which are commonly PVC-based. Structurally closer to PVC, poly(vinylidene chloride) was tested in ion-selective membranes without plasticizer and gave satisfying results with an extended lifetime (Wotring et al., 1991, Analyst, 116, 581-584).

[0019] On the other hand, attempts to immobilise ionophores directly onto PVC chains have been performed using carboxylated-PVC (Daunert et al., 1990, Anal Chem, 62, 1428-1431) or with azide-modified PVC through a click reaction (Liu et al, 2012, Sensors and Actuators B: Chemical, 171-172, 556-56) both for potassium-selective membranes.

[0020] Therefore, preventing the migration of plasticizers is of huge interest to the sensor field as it holds the key to suppressing potential drifts occurring because of this leaching process. It is also a desired characteristic for wearable ion-selective membrane-based sensors as these plasticizers are potentially harmful.

[0021] Therefore, there is a need for providing new solutions for obtaining leach-free PVC-based materials not only for wearable sensor applications, where cytotoxicity is a concern but also for routine laboratory use, where recalibration is often required.

[0022] Summary of the Invention

[0023] A general object of this invention is to provide plasticizer-like agents useful in the preparation of self-plasticized PVC.

[0024] One of the specific objects of this invention is to provide plasticizer-like agents. It is advantageous to provide plasticizer-like agents allowing to prepare PVC-based polymers with advantageous physical properties (e.g. stretchiness and flexibility) allowing to form films without the need of the addition of further plasticizers.

[0025] An object of this invention is to provide PVC-based polymers with advantageous physical properties, in particular suitable for use as matrix in ion-selective electrodes.

[0026] It is advantageous to provide plasticizer leak-free PVC-based polymers.

[0027] It is also advantageous to provide PVC-based polymers with advantageous ion diffusion properties allowing to coat ion-selective electrodes without the need to add an agent to facilitate ion diffusion through the ion-selective membrane.

[0028] Another object of this invention is to provide a use of self-plasticized PVC material as a matrix for ion-selective electrodes.

[0029] It is also advantageous to provide ion-selective electrodes with high stability and lifetime.

[0030] Disclosed herein is a plasticizer-like agent useful in the preparation of PVC-based polymers.

[0031] Also disclosed herein is a method of preparation of a plasticizer-like agent of the invention.

[0032] Also disclosed herein is a method of preparation of a self-plasticized PVC material according to the invention.

[0033] Also disclosed herein is a self-plasticized PVC material according to the invention and its use as a matrix for ion-selective electrodes.

[0034] Also disclosed herein is an ion-selective comprising a matrix comprising a self-plasticized PVC material according to the invention.

[0035] Brief Description of the drawings

[0036] Fig. 1 represents potentiometric time trace (A, F) and impedance measurements (B, C, D, E) obtained with different matrices as described in Example 2. A and B: potassium-selective electrode in 1 mM KC1 coated with control self-plasticized PVC (C-PVC) (not from the invention); C: potassium-selective membrane based on polymer dl in 0.1 M KC1; D: pH electrode in universal buffer 0.04M pH 7; E and F: potassium-selective membrane based on polymer d2. Reference electrode: double-junction Ag / AgCl / 3 M KC1 / 1 M LiOAc and counter electrode: Pt rod. Impedance measurements taken at OCP with 100 mV amplitude at a frequency range of 1 MHz to 100 mHz. Resistance estimated using semi-circle fit. Error bars are standard deviations (n = 3). Fig. 2 reports the potentiometric response of a potassium-selective electrode prepared with self-plasticized PVC dl as described in Example 2. A: Response after initial conditioning (circles), after 4 days (triangles) and after 5 days (squares); B: Fixed interference method (FIM) to determine selectivity coefficient. Potassium response in 0.1 M MgCh background (circles) and potassium response in 1 M MgCh (triangles). The arrows indicate the lower detection limit. Error bars are standard deviations (n = 3).

[0037] Fig. 3 reports the potentiometric response the potentiometric response of pH-selective electrode prepared with self-plasticized PVC dl as described in Example 2. Circles represent initial response after conditioning, triangles are the response on day 3 and squares are the response on day 21. Error bars are standard deviations (n = 3).

[0038] Fig. 4 represents the potentiometric response of pH-selective electrodes prepared with selfplasticized PVC dl as described in Example 2, with 20 % wt DEHP (circles) and no added DEHP (triangles).

[0039] Detailed description of embodiments of the invention

[0040] The expression “plasticizer” refers to a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and / or to decrease friction during its handling in manufacture.

[0041] The term “C4-C16 alkyl” when used alone or in combination with other terms, comprises a straight chain or branched C4-C16 alkyl which refers to monovalent alkyl groups having 4 to 16 carbon atoms. This term is exemplified by groups such as 2-et-hexyl and / / -butyl.

[0042] The invention is based on the unexpected finding that new plasticizer-like agents can be advantageously used for the preparation of self-plasticized PVC material capable of forming films with advantageous physical properties and requiring no additional plasticizer to facilitate ion diffusion through the film. Films of this new self-plasticized PVC material were used to prepare ion-selective membranes which showed to be highly stable and have an extended lifetime.

[0043] This new self-plasticized PVC material is applicable as matrix for ion-selective electrodes as demonstrated with potassium- and pH-selective electrodes that both showed superior stability over time compared to the current state of the art. Other selective electrodes could be prepared such as magnesium-, calcium-, sodium-, lithium-, chloride-, nitrate-, nitrite- and carbonateselective electrodes with these new self-plasticized polymers according to the same methodology. According to a particular aspect, is provided a method for the preparation of a self-plasticized

[0044] PVC material, said method comprising: a) Providing a plasticizer-like agent of Formula (I):

[0045] (I) wherein q is an integer selected from 0 to 14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to 14; R4 is selected from H and a straight or branched Ci-Cs alkyl; XI, X2 and X3 are independently selected from H and a group of Formula (II), wherein at least one of XI to X3 is not H: wherein x is an integer selected from 3 to 10; y is an integer from 0 to 8; R1 is selected from a straight or branched C4-C16 alkyl and R2 is selected from a straight or branched C4-C16 alkyl; b) Reacting said plasticizer-like agent with PVC azide of Formula (III) through a click reaction: (HI) wherein p is an integer comprised between 5 and 40 and n is an integer between 10 and 55 and n+p is an integer comprised between 50 and 60; c) Isolating the obtained self-plasticized PVC material of Formula (IV):

[0046] (IV) , wherein n, p, q, o, R4, XI, X2 and X3 are as defined herein.

[0047] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention, wherein the plasticizer-like agent of the invention is reacted with PVC azide through until full replacement of the azide groups with the tethered plasticizer-like moiety from the plasticizer-like agent (e.g. from about to 24h to about 80h, for example about 72h).

[0048] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention, wherein the plasticizer-like agent is reacted with PVC azide at a temperature from about 35°C to about 45°C (e.g. 42°C).

[0049] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention, wherein the click reaction is carried out in presence of copper as catalyst.

[0050] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention wherein a mass ratio of plasticizer-like agents to PVC of 35 to 70 % (e.g. 50%) is used.

[0051] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention, wherein the self-plasticized PVC material is isolated by precipitation from a polar solvent such as methanol.

[0052] According to another particular aspect, is provided a method for the preparation of a selfplasticized PVC material according to the invention, wherein the self-plasticized PVC material is isolated by ball milling under the glass transition temperature of the said self-plasticized PVC. (e.g. under -35°C).

[0053] According to another particular aspect, is provided a plasticizer-like agent of Formula (I): wherein q is an integer selected from 0 to 14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to 14; R4 is selected from H and a straight or branched Ci-Cs alkyl; XI, X2 and X3 are independently selected from H and a group of Formula (II), wherein at least one of XI to X3 is not H: wherein x is an integer selected from 3 to 10; y is an integer from 0 to 8; R1 is selected from a straight or branched C4-C16 alkyl, R2 is selected from a straight or branched C4-C16 alkyl.

[0054] According to a particular embodiment, x is an integer selected from 3 to 6.

[0055] According to a particular embodiment, x is 3.

[0056] According to a particular embodiment, x is 6.

[0057] According to a particular embodiment, x is 10.

[0058] According to a particular embodiment, y is 0.

[0059] According to a particular embodiment, XI and X2 are H.

[0060] According to a particular embodiment, the sum q+o is an integer from 1 to 6.

[0061] According to a particular embodiment, the sum q+o is 1.

[0062] According to a particular embodiment, the sum q+o is 6.

[0063] According to a particular embodiment, the sum q+o is an integer from 2 to 6.

[0064] According to a particular embodiment, R1 is hexyl.

[0065] According to a particular embodiment, R2 is hexyl.

[0066] According to a particular embodiment, R4 is H. According to a particular embodiment, a plasticizer-like agent is of Formula (la): wherein m is an integer from 2 to 4 and x and R1 and R2 are as defined herein.

[0067] According to a particular embodiment, a plasticizer-like agent of Formula (I’): wherein m is an integer from 2 to 4 and R is 2-Et- hexyl.

[0068] According to a particular embodiment, a plasticizer-like agent of Formula (I) is prepared by a Fisher esterification of a dicarboxylate compound of Formula (V) with an acid compound of Formula (VI): wherein x is an integer selected from 3 to 10, R1 is selected from a straight or branched C4-C16 alkyl, R2 is selected from a straight or branched C4-C16 alkyl; R3 is a moiety of the following formula (VII):

[0069] (VII) and wherein q is an integer selected from 0 to 14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to 14; X4 is selected from H, COOH and (CH2)yiCOOH; X5is selected from H, COOH and (CH2)y2COOH; X6is selected from H, COOH and (CH2)y3COOH, wherein at least one of X4 to Xe has a carboxylic acid group; R4 is selected from H and a straight or branched Ci-Cs alkyl and yi, y2and ys are an integer from 1 to 8.

[0070] According to a particular embodiment, the acid compound of Formula (VII) is of the following Formula A:

[0071] O (A) wherein m is an integer selected from 2 to 4. According to a particular embodiment, the acid compound of Formula (VII) is 6-heptynoic acid.

[0072] According to a particular embodiment, the acid compound of Formula (VII) is 10-undecynoic acid.

[0073] According to a particular embodiment, the dicarboxylate compound of Formula (V) is reacted with an acid compound of Formula (VII) for about 2h under stirring.

[0074] According to another particular aspect, is provided a self-plasticized PVC material of Formula wherein n, p, q, o, R4, XI, X2 and X3 are as defined herein. According to a particular embodiment, is provided a self-plasticized PVC material of Formula

[0075] (IVa): wherein x, n, p, m, R1 and R2 are as defined herein.

[0076] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein x is 3-10.

[0077] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein x is 3.

[0078] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein x is 6.

[0079] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein x is 10.

[0080] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein m is 4.

[0081] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein m is 2.

[0082] According to a particular embodiment, at least one of R1 and R2 is optionally substituted hexyl. According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein R1 and R2 are optionally substituted hexyl.

[0083] According to a particular embodiment, at least one of R1 and R2 is 2-Et-hexyl.

[0084] According to a particular embodiment, is provided a self-plasticized PVC material of Formula (IVa) wherein R1 and R2 are 2-Et-hexyl.

[0085] According to a particular embodiment, is provided a self-plasticized PVC material is a polymer dl: and p are as defined herein.

[0086] According to a particular embodiment, is provided a self-plasticized PVC material in a polymyer d2: d2, wherein n, and p are as defined herein.

[0087] According to a particular embodiment, is provided a self-plasticized PVC material in a polymer d3: d3, wherein n, and p are as defined herein. According to a particular embodiment, is provided a self-plasticized PVC material in a polymyer d4: d4, wherein n, and p are as defined herein.

[0088] According to a further particular aspect, is provided a self-plasticized PVC material of the invention having an average molecular weight from about 30 kDa to about 300 kDa.

[0089] According to a further particular aspect, is provided a use of a self-plasticized PVC material of Formula (IV) for the preparation of an ion-selective membrane. The said ion-selective membrane can be drop-cast, spin-coated or spotted from a solvent-based solution to form a film of self-plasticized PVC material according to the invention.

[0090] According to a further particular aspect, is provided a sensor comprising an ion-selective membrane comprising a self-plasticized PVC material of the invention. Potassium and pH sensors are presented as examples but not limited to it. Other selective electrodes could be prepared such as magnesium-, calcium-, sodium-, lithium-, chloride-, nitrate-, nitrite- and carbonate-selective electrodes with the new self-plasticized polymers of the invention according to the same methodology.

[0091] EXAMPLES

[0092] Reagents and Materials

[0093] All aqueous solutions were prepared in deionised water (>18 MQ cm). Poly(vinyl chloride) (Selectophore™, PVC), sodium azide (>99.5%, NaNs), / / ra-toluenesulfonic acid monohydrate (>98.5%, / ?TSA), sodium chloride (>99.5%, NaCl), potassium chloride (>99.5%, KC1), lithium chloride (>99.0%, LiCl), sodium bicarbonate (>99.5%, NaHCCh), magnesium chloride hexahydrate (>99.0%, MgCh), calcium chloride (>97.0%, CaCh), 3 -azido- 1 -propanol (>96.0%), 10-undecynoic acid (95.0%), 6-heptynoic acid (95.0%), copper(II) sulfate pentahydrate (>96.0%), L-ascorbic acid (>98.0%), sodium tetrakis[3,5- bis(trifluoromethyl)phenyl]borate (>95.0%, Selectophore™, NaTFPB), tridodecylamine (Selectophore™, H-ionophore(I)), valinomycin (Selectophore™, K-ionophore(I)), bis(2- ethylhexyl) phthalate (Selectophore™, DEHP), (phosphoric acid (>85.0 wt.%, H3PO4), and tetrahydrofuran (>99.5%, Selectophore™, THF) were purchased from Sigma- Aldrich. Laboratory reagent grade toluene, analytical reagent grade chloroform (>99.8%, CHCh), laboratory reagent grade ethyl acetate (>99.0%, EtOAc) and analytical reagent grade tetrahydrofuran (>99.8, THF) were purchased from Fisher Scientific.

[0094] Anhydrous magnesium sulfate (>98.0%, MgSCU) was purchased from Santa Cruz Biotechnology. 2-Ethyl-l -hexanol (>99.0%) was purchased from Fluka Analytical. Acetylenedicarboxylic acid (97%) was purchased from abcr. Methanol (99.0%, MeOH) was purchased from Thommen-Furler AG. Ethynylferrocene (97%), citric acid monohydrate (99.5%) and boric acid (99.5%, H3BO3) were purchased from Acros Organics. N,N- Dimethylformamide (99.5%, DMF) and standardised sodium hydroxide (2.0 N, NaOH) were purchased from Thermo Scientific. Potassium tetrakis(pentafluorophenyl)borate (>97%, KTPFPB) was purchased from Alfa Aesar. HPLC grade acetonitrile (>99.5%, ACN) and HPLC grade n-hexane (97.0%) were purchased from VWR Chemicals. EDOT-C14 was synthesised in house according to reference (Guzinski et al. , 2017, Anal Chem, 89, 8468-8475).

[0095] Example 1: Preparation of a self-plasticized PVC material according to the invention

[0096] A self-plasticized PVC material according to the invention was carried out using plasticizerlike agent according to the invention as follows:

[0097] PVC-azide synthesis

[0098] PVC-azide (PVC-N3) was synthesised according to Higa et al, 2018, supra as illustrated under Scheme 1 below:

[0099] Scheme 1 wherein 1, n and p are integers dependently selected from 0 to 100, where 1 is between 50 and 60 and n is equal to 1 - p and p is comprised between 5 and 40.

[0100] In short, 5.0 g of poly(vinyl chloride) was dissolved in 100 mL dimethylformamide at 65°C. 5.2 g of sodium azide were then added to the reaction flask and the mixture was stirred for 2.5 h. The reaction medium was then precipitated in 500 mL of ice-cold methanol. The resulting precipitate was then filtered through a Buchner funnel using a 0.45 pm nylon filter. The polymer was then dissolved in 50 mL dimethylformamide, precipitated in 300 mL ice-cold methanol and filtered through a Buchner funnel using a 0.45 pm nylon filter. This process was repeated one more time and the final resulting polymer was dried under vacuum for 3 days to give 4.42 g of flocculent white solid. The azide modification was confirmed by FT-IR analysis comparing non-modified PVC and azide-modifed PVC and the presence of azide groups on the PVC backbone can be confirmed by the typical azide band present at -2100 cm'1. The degree of azide modification was estimated to 14.0% by spectrophotometry after reaction with ethynylferrocene according to the protocol described in Pawlak et al., 2010, Anal Chem, 2010, 82, 6887-6894.

[0101] Synthesis of di(2-ethylhexyl) acetylenedicarboxylate a

[0102] Di(2-ethylhexyl) acetylenedi carb oxy late a was synthesised through a simple Fischer esterification reaction from acetylenedicarboxylic acid and 2-ethyl-l -hexanol with para- toluenesulfonic acid as acid catalyst as described in Earla et al., 2014, supra as illustrated under Scheme 2 below:

[0103] Scheme 2

[0104] HO OH pTSA, toluene, 1 h OR OR

[0105] Dean-Stark apparatusa

[0106] R = 2-Et-hexyl

[0107] Acetylenedicarboxylic acid (4.1 g, 35.8 mmol), 2-ethyl-l -hexanol (10.3 g, 78.8 mmol) and / ?ara-toluenesulfonic acid monohydrate (0.4 g, 2.1 mmol) were dissolved in 56 mL of toluene. The reaction mixture was refluxed for 1 h at 110 °C with a Dean-Stark to remove the water byproduct. The reaction mixture was then cooled down and poured in 40 mL saturated sodium chloride. The aqueous layer was then extracted twice with 40 mL of hexane. The organic layers were combined, washed sequentially with 40 mL water and saturated sodium bicarbonate and finally dried over anhydrous magnesium sulfate. The volatiles were then evaporated under reduced pressure and the resulting crude yellow oil was purified by flash chromatography using 95:5 hexane / ethyl acetate as eluent. 9.0 g of the final product were obtained as a colourless oil (74.2 % yield). 'H NMR (400 MHz, CDC13): 5 4.22-4.14 (m, 4H), 1.69-1.61 (m, 2H), 1.43- 1.37 (m, 4H), 1.35-1.28 (m, 12H), 0.92 (t, 12H).

[0108] 2-ethyl-l -hexanol is presented here as an example, but other type of alcohols, such as linear alcohols ranging from butanol to hexadecanol or all other types of branched alcohol could be used to generate a wide variety of compounds a with R groups differing from 2-Et-hexyl.

[0109] Synthesis of a dicarboxylate compound of Formula (V) wherein x is 3 and R1and R2are 2- Et-hexyl: bis(2-ethylhexyl) l-(3-hydroxypropyl)-lH-l,2,3-triazole-4,5-dicarboxylate b

[0110] In a second step, bis(2-ethylhexyl) l-(3-hydroxypropyl)-lH-l,2,3-triazole-4,5-dicarboxylate b was synthesised through a thermal click reaction from compound a and commercially available 3 -azido- 1 -propanol as shown under Scheme 3 below. The latter compound was employed in practice but could be replaced by similar compounds exhibiting a variable carbon chain length of (CH2) 3 to 10 between the azide and alcohol functionality.

[0111] One should be careful when working with organic azides as they are prone to violent decomposition upon input of light, heat or shock. A thermal click reaction was preferred here instead of a copper-catalysed one because of the nature of the alkyne. Evidence suggests that the first step in the catalytic copper cycle is the deprotonation of the terminal alkyne and formation of copper (I) acetylide (Hein etal., 2010, Chemical Society Reviews, 39, 1302-1315') which is not possible in the case of a disubstituted alkyne. The 1,3-dipolar cycloaddition afforded the formation of a disubstituted triazole five membered ring structurally similar to di(2-ethylhexyl)phthalate.

[0112] Scheme 3

[0113] 3 -Azido- 1 -propanol (0.5 g, 5.0 mmol) and di(2-ethylhexyl) acetylenedi carb oxy late a (1.5 g, 4.5 mmol) were dissolved in 12 mL chloroform. The reaction mixture was stirred at 50 °C for 24 h. The volatiles were then evaporated under reduced pressure and the resulting crude colourless oil was purified by flash chromatography using 7:3 hexane / ethyl acetate as eluent.

[0114] 1.7 g of the final product were obtained as a colourless oil (85.9 % yield).JH NMR (400 MHz, CDC13): 5 4.74 (t, 2H), 4.38-4.2 (m, 4H), 3.63 (t, 2H), 2.16 (q, 2H), 1.78-1.65 (m, 2H), 1.44- 1.26 (m, 17H), 0.92 (t, 12H).

[0115] Synthesis of a plasticizer-like agents of Formula (I) according to the invention bis(2-ethylhexyl) l-(3-(undec-l 0-ynoyloxy)propyl)-lH-l,2,3-triazole-4, 5-dicarboxylate (cl ) A fisher esterification of a dicarboxylate compound of Formula (V) wherein x is 3 with an acid compound of Formula (VI) wherein R3 is a compound of Formula (A) as defined above wherein m is 4 to obtain a plasticizer-like agent of Formula (F) wherein m is 4 and R is Bis(2- Et-hexyl) was carried out from Higa et al., 2018, supra to lead to (cl) as shown in Scheme 3 above and as detailed below:

[0116] Bis(2-ethylhexyl) l-(3-hydroxypropyl)-lH-l,2,3-triazole-4,5-dicarboxylate b (1.62 g, 3.7 mmol), 10-undecynoic acid (0.5 g, 2.7 mmol) and / / ra-toluene sulfonic acid monohydrate (28.0 mg, 0.15 mmol) were dissolved in 4 mL of toluene. The mixture was stirred at reflux for 2 h using a Dean-Stark to remove the water by-product. The volatiles were then evaporated under reduced pressure and the resulting crude light brown oil was purified by flash chromatography using 4:1 hexane / ethyl acetate as eluent. 1.1 g of the final product were obtained as a colourless oil (67.5 % yield). 'H NMR (400 MHz, CDC13): 5 4.7 (t, 2H), 4.34- 4.23 (m, 4H), 4.14 (t, 2H), 3.64 (s, 1H), 2.32-2.23 (m, 4H), 2.21-2.14 (td, 2H), 1.77-1.65 (m, 2H), 1.45-1.27 (m, 28H), 0.94-0.88 (m, 12H). bis(2-ethylhexyl) l-(3-(hept-6-ynoyloxy)propyl)-lH-l,2,3-triazole-4, 5-dicarboxylate (c2)

[0117] The synthesis of (c2), a plasticizer-like agent of Formula (I’) wherein m is 2 and R is 2-Et- hexyl was identical to that of (cl) using an acid compound of Formula (VI) wherein R3 is a compound of Formula (A) and wherein m is 2 (heptynoic acid instead of 10-undecynoic acid to synthesize c2). 85.2 mg of final product were obtained as a colourless oil (23.1% yield). 'H NMR (400 MHz, CDCI3): 5 4.73 (t, 2H), 4.36-4.22 (m, 4H), 4.16 (t, 2H), 2.61-2.53 (m, 1H), 2.38-2.23 (m, 4H), 1.75-1.70 (td, 2H), 1.62-1.54 (m, 2H), 1.46-1.23 (m, 20H), 0.97-0.85 (m, 12H). bis(2-ethylhexyl) l-(3-(undec-l 0-ynoyloxy)hexyl)-lH-l, 2, 3-triazole-4, 5-dicarboxylate (c3) This compound of Formula (la) wherein m is 4, n is 6 and R1 and R2 being Bi s(2 -Et-hexyl) was obtained in a similar manner as for compounds cl-c2 above. The obtained yield was about 85%. bis(2-ethylhexyl) l-(3-(undec-l 0-ynoyloxy)decyl)-lH-l, 2, 3-triaz.ole-4, 5-dicarboxylate (c4) This compound of Formula (la) wherein m is 4, n is 10 and R1 and R2 being Bis(2-Et-hexyl) was obtained in a similar manner as for compounds cl-c2 above, while stirring was allowed for additional 2 days. The obtained yield was about 87%.

[0118] Synthesis of a self-plasticized PVC material according to the invention

[0119] Self-plasticized PVC material of Formula (IV), in particular (IVa) wherein x is 3, n is 43, p is 14, m is 4, R1 and R2 are 2-Et-hexyl (dl) PVC-Ns (120 mg) synthesized above and the plasticizer-like agent of the invention (cl) (bis(2- ethylhexyl)l-(3-(undec-10-ynoyloxy)propyl)-lH-l,2,3-triazole-4,5-dicarboxylate) were subjected to a click reaction in presence of copper as catalyst as follows:

[0120] (0.52 g, 0.86 mmol) were dissolved in 5 mL dimethylformamide. Copper sulfate and L-ascorbic acid were added to the reaction mixture in catalytic amounts to promote the “click” reaction. The reaction medium was heated and stirred at 45°C for 72 h to ensure full replacement of the azide groups with the tethered plasticizer-like moiety. The polymer was then isolated by precipitation in 100 mL of ice-cold methanol and filtration through a Buchner funnel using a 0.45 pm nylon filter. The obtained polymer was dissolved one more time in 10 mL tetrahydrofuran, precipitated in 100 mL of ice-cold methanol and filtered through a Buchner funnel using a 0.45 pm nylon filter. The final product (dl) was then dried under vacuum for 3 days. 303.2 mg of a stretchy light greenish polymer were finally obtained. The full conversion of the azide groups on the PVC backbone was confirmed by FT-IR since the absence of azide groups on the PVC backbone can be confirmed by the disappearance of the typical azide band present at -2100 cm’1. DSC (Tg): -32.7 °C.

[0121] Self-plasticized PVC material of Formula (IV), in particular (IVa) wherein x is 3, n is 43, p is 14, m is 2, R1 and R2 are 2-Et-hexyl (d2)

[0122] The synthesis procedure was identical to that of (dl). 80.6 mg of stretchy light brownish polymer was isolated and the conversion of the azide groups on the PVC backbone was estimated by FT-IR. DSC (Tg): 17.5 °C.

[0123] Purifications had to be done between each step to avoid cross-reaction during click reaction, especially for the last step. The final product presented itself as a light greenish stretchy polymer, even upon full drying.

[0124] A control self-plasticized PVC (C-PVC) (not from the invention) was prepared by a direct attachment of di(2-ethylheyl) acetylenedi carb oxy late a on PVC-N3. Although showing some initial promising flexibility, the resulting polymer formed a flaky solid upon full drying.

[0125] Self-plasticized PVC material of Formula (IV), in particular (IVa) wherein x is 6, n is 43, p is 14, m is 4, R1 and R2 are 2-Et-hexyl (d3)

[0126] This compound was obtained in a similar manner as for dl and d2, except that the reaction temperature was about 65-70°C to speed-up the reaction. The obtained yield was about 75%.

[0127] Self-plasticized PVC material of Formula (IV), in particular (IVa) wherein x is 10, n is 43, p is 14, m is 4, R1 and R2 are 2-Et-hexyl (d4) This compound was obtained in a similar manner as for dl and d2, except that the reaction temperature was about 65-70°C to speed-up the reaction. The obtained yield was about 73%.

[0128] Example 2: Use of a self-plasticized PVC material according to the invention for the preparation of an electrode

[0129] The applicability of the self-plasticized PVC material as a matrix for ion-selective electrodes, potassium-selective membranes were prepared using self-plasticized PVC of the invention without any added plasticizer as follows:

[0130] Electrode Preparation

[0131] A polymerisation solution used to generate the transducing layer was made of 0.01 M of EDOT-Cw (2-tetradecyl-2,3-dihydrothieno[3,4-Z>][l,4]dioxine) and 0.03 M of potassium tetrakis(pentafluorophenyl)borate (KTPFPB) in acetonitrile as previously reported in Forrest et al., 2020, Electroanalysis, 32, 799-804. The PEDOT-C14 transducing films were generated on clean GC electrodes by dynamic electropolymerisation (cyclic voltammetry), from -1.25 V to 1.3 V at a scan rate of 0.1 V s'1for 2 cycles. The transducing layer was then prepolarised by applying a constant potential in a solution of 0.03 M of KTPFPB in acetonitrile to reach an oxidation ratio of 50:50 between PEDOT-Ci4° / PEDOT-Ci4+(Zdrachek et al., 2023, Analytica Chimica Acta, 1239, 340652).

[0132] The prepolarisation potential was chosen as the potential corresponding to the oxidation peak apex. The electrodes were then air-dried for 30 min.

[0133] In each case, for the preparation of the electrode coating, a membrane casting solution, or also called membrane cocktail, was prepared by dissolving 30 mg of a self-plasticized PVC according to the invention into 300 pL of THF (Selectophore™ grade). 10 mmol / kg NaTFPB (ion-exchanger) were then dissolved in the cocktail along with 30 mmol / kg ionophore (respectively H-ionophore (I) for pH and valinomycin for potassium). A total amount of 150 pL (3 times 50 pL) of membrane cocktail was drop cast onto the electrode body obtained as described above and left to dry overnight.

[0134] Prior to analysis, the sensors were conditioned in 0.1 M of corresponding ion. For pH measurements, the electrodes were conditioned in universal buffer (citric acid, boric acid and phosphoric acid at 0.04 M) at pH 7. All further pH measurements were always carried out in the same universal buffer adjusted with 2 M NaOH. All activity coefficients were calculated according to Meier et al., 1982, Analytica Chimica Acta, 136, 363-368.

[0135] The ion-selective membrane cast with the control self-plasticized PVC (C-PVC) formed a solid film that acted as a complete barrier to ion diffusion. As seen in Figure 1A, even after overnight conditioning, the potential of the membrane failed to remain stable in a solution of fixed concentration, exhibiting a drift of more than 1.5 V in 25 min. The impedance spectrum recorded for the same membrane - Figure IB) failed to provide a semi-circle shape in the Nyquist plot, typically observed for plasticized ion-selective membranes.

[0136] Polymer dl was cast as described above. Owing to their high resistance (R = 894 MQ - Figure 1C), the sensors were conditioned overnight in 0.1 M KC1 (instead of the typical 1 mM KC1) to promote the equilibration of the membrane. The high resistance of the membrane is here attributed to immobilisation of the plasticizer analogue onto the PVC backbone as the formation of covalent bonds tends to reduce the mobility and rigidifies the structure.

[0137] The elasticity of the self-plasticized PVC of the invention dl was tested via the stretching by hand without tearing of a membrane cast with polymer dl as described above. The extend of the stretch can be visually appreciated by looking at the black round dot in the centre, which upon mechanical stress becomes oval. The prepared polymer exhibited a water contact angle of 108.5°, which is sufficiently hydrophobic to prevent excess of water penetrating the membrane, while remaining hydrophilic enough to not fully repel water at the surface. The glass transition temperature was measured by differential scanning calorimetry and estimated at -32.7°C, which is higher than traditional PVC - DEHP (-60 °C) (Higa et al., 2018, supra) membranes but still sufficient to be flexible at room temperature and suitable for ion-selective membranes.

[0138] When comparing FigurelB and Figure 1C, it can be seen that the implementation of a linker between the triazole group and the plasticizer-like moiety is necessary to have a functional ion- selective membrane. Although increasing the plasticization efficiency, this linker brings a slight waxiness to the membrane that was observed visually. To emphasise this observation, membranes with different thicknesses were prepared and photographed. The thicker the membrane, the blurrier it becomes, emphasising this slight wax-like texture.

[0139] To confirm whether such a longer linker was really needed to have self-plasticizing properties, the self-plasticized PVC according to the invention (d2), was also tested. Shortening the linker length by 4 carbons resulted in slightly decreased self-plasticizing efficiency as demonstrated by the increased glass transition temperature (from -32.7°C for dl to 17.5°C for d2). With a glass transition temperature below operating temperature (room temperature), compound d2 can be qualified as self-plasticizing and was dissolved in THF along with NaTFPB (ionexchanger) and valinomycin (ionophore) and casted on top of the transducer as described above to generate a self-plasticized potassium-selective electrodes. In this case, the resistance of the membrane was also high as seen with that of those prepared with polymer dl (R = 8.1 G - Figure IE) and therefore the sensors were also conditioned overnight in 0.1 M KC1 (instead of the typical 1 mM KC1) to promote the equilibration of the membrane. As expected with a high membrane resistance and glass transition temperature close to operating temperature, the response towards potassium was slightly sub-Nernstian (Figure IF) and the response range was moderately limited (between -4.7 and -1.8).

[0140] Those results indicate that shortening the linker to less than 4 carbons will likely result in nonfunctional sensors.

[0141] Ion-selective membranes based on polymer d2, after adequate overnight conditioning in 0.1 M KC1, responded adequately to potassium, as seen in Figure 2A. A linear response region can be observed between -5.5 and -1, which is slightly shrunk compared to regular potassium ion- selective electrodes, but coherent with the high resistance of the membrane. In practice, a lower detection limit of -5.5 is sufficient to allow selective detection of potassium in environmental and biological matrixes. On the other hand, it can be noticed that the E° values between day 1 and day 4 only differ by 6.3 mV, confirming the high stability of this system. It can be seen here that the response slope gets closer to Nernstian between day 1 and 4, confirming that a longer conditioning time is beneficial. This inconvenience is counterbalanced by the fact that once the membrane is fully equilibrated, the signal is extremely stable (1.1 mV difference of E° value between day 4 and 5) and the slope remains constant as demonstrated in Figure 2A where the green and red traces are perfectly overlapped in the linear region. Although this equilibration time seems long, previous work using the same PEDOT-Cw transducer reported a drift of 37.7 mV between the first testing day and the fifth, much larger than what is observed here (Forrest et al., 2020, supra). In the same piece of work, the E° value stabilised between day 5 and 10 EE° = 6.2 mV), but never reached the level of stability with the self-plasticized membranes described here.

[0142] Nowadays, the standard procedure to determine unbiased selectivity coefficient is the so-called modified separate solution method (MSSM) (Bakker, 1997, Anal Chem, 1997, 69, 1061-1069) where the response towards discriminating ions is measured before the ion of interest. Owing to the long equilibration time of this system, this procedure is unfortunately not suitable and fixed interference method (FIM) was chosen instead. The response towards potassium was recorded in a fixed background of interfering ion and the selectivity coefficient was estimated using the following equation: where ai(LDL) is activity of the primary ion at the detection limit and aj the activity of the interfering ion. As seen in Figure 2B, the response towards potassium was measured in two different background of interfering ion, in this example magnesium, to confirm that the baseline signal of the interfering ion would shift according to the Nernst equation. Both experiments gave similar values of the calculated selectivity coefficient confirming the good behaviour of the membrane. All calculated selectivity coefficient for the self-plasticized potassium selective membrane can be found in Table 1 where the calculated potentiometric selectivity coefficient for potassium-selective electrode prepared with self-plasticized PVC dl by FIM are presented:

[0143] Table 1 j l°gKJrt

[0144] Mg^ -4.8

[0145] (Pa2-4.6

[0146] Li+-4.2

[0147] Na -3.9

[0148] The selectivity coefficient over sodium is especially interesting, as it is the often the main interfering ion in natural and biological samples, giving an estimated value of logK^°tNa+= - 3.9, which only slightly deviates from the traditionally reported value, -4.5, for a similar system (Bakker, 1996, Journal of The Electrochemical Society, 143, LBS').

[0149] This close to 4-fold selectivity towards sodium is still sufficient to ensure adequate detection of potassium in real samples. The deviation of overall selectivity coefficients compared to published values likely originates from the reduced response range and brand-new type of matrix used here.

[0150] To confirm the applicability of the new self-plasticized matrix to other systems, pH solidcontact ion-selective were also prepared and tested. To confirm the stability of the E° value that was observed with potassium-selective electrodes, the newly prepared pH sensors were tested over a 3 -week time period.

[0151] As seen in Figure 3, the observed trend is the same as with the potassium-selective electrode. The response slope gets closer to an ideal value after a couple of days, while the E° value exhibits an initial shift EE between day 1 and 3 is of 10.06 mV). This process again is likely due to the longer equilibration period needed for this matrix. The resistance of this membrane was also estimated by impedimetric measurement and found to be of the same order of magnitude as the potassium sensor (R = 208 M - Figure ID). Between day 3 and 21, the EP value and response slope both remained constant, suggesting no appreciable leaching of membrane components. Sensors exhibiting such high stability over time are desired for field applications for example, where daily calibration is often cumbersome. Additionally, the membranes prepared using the self-plasticized polymers dl or d2 also exhibited an enhanced adhesion to the PEEK body located around the active area of the electrode. This characteristic is especially attractive for field application, more precisely water analysis, where turbulent flows often promote membrane falloff, thus premature deterioration of the sensor.

[0152] In the basic pH region, at low H+concentration, it is also seen that the response range deviates compared to PVC-DEHP electrodes prepared with the same H-ionophore(I). To rule out solubility issues of membrane components in this plasticizer-free system, a membrane containing 20% wt DEHP was prepared and tested as comparison purpose. As seen in Figure 4, the additional amount of DEHP did not alter the response significantly, indicating that the membrane components are well solubilised in the self-plasticized PVC matrix. Although the response range is shorter (pH 3 - 9) than that with classical pH electrodes, it is still linear within the biological and environmental pH range and thus suitable for many applications. The enhanced stability of the signal depicted in Figure 3 makes them particularly attractive.

[0153] Laboratory Electrochemical Equipment

[0154] Glassy carbon (GC) electrodes from Metrohm (0 3.00 ± 0.05 mm, body diameter 10.00 ± 0.05 mm) were polished using different diamond powder suspensions (0 6-3-1-0.25 pm) prior to use. Electropolymerisation of the transducing layer was performed in a three electrodes system using a PGSTAT101 (Metrohm Autolab, B.V., Utrecht, The Netherlands) controlled by the Nova 1.8 software. A platinum electrode was used as a quasi-reference with a glassy carbon rod as counter electrode. Impedimetric measurements were performed using a PGSTAT302N (Metrohm Autolab, B.V., Utrecht, The Netherlands), controlled by the Nova 2.1 software, with a double-junction Ag / AgCl / 3 M KC1 / 1 M LiOAc (Metrohm, Switzerland) as reference and a platinum rod as counter electrode. All potentiometric measurements were performed using a high impedance input 16-channels EMF monitor (Lawson Laboratories, Inc., Malvern, PA) to record the signal with a double-junction Ag / AgCl / 3 M KC1 / 1 M LiOAc (Metrohm, Switzerland) as reference electrode. All electrochemical measurements were carried out in a Faraday cage to prevent unwanted noise. Pictures were taken using a Canon EOS 5D Mark III camera equipped with a Canon MP-E 65 mm f / 2.8 macro lens. If needed, the pictures were processed with Image J. H-NMR measurements were performed in deuterated chloroform at 400 MHz and FT-IR spectrum were taken with a Tensor 27 IR instrument both from Bruker. Differential scanning calorimetry (DSC) measurements were performed with a DSC 1 STARe system from Metier Toledo under N2 from -90 to 180 °C with a 10°C / min heating ramp.

[0155] Altogether, those data support the untapped potential of self-plasticized PVC as matrix for ion- selective electrodes. With the covalent attachment of the plasticizer, leaching processes are suppressed, making this system highly desirable for wearable or environmental sensors. It is believed that due to the simple and modulable synthetic pathway, a wide variety of new selfplasticized polymers can be generated.

Claims

Claims1. A method for the preparation of a self-plasticized PVC material, said method comprising: a) Providing a plasticizer-like agent of Formula (I):wherein q is an integer selected from 0 to 14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to 14; R4 is selected from H and a straight or branched Ci-Cs alkyl; XI, X2 and X3 are independently selected from H and a group of Formula (II), wherein at least one of XI to X3 is not H:wherein x is an integer selected from 3 to 10; y is an integer from 0 to 8; R1 is selected from a straight or branched C4-C16 alkyl, R2 is selected from a straight or branched C4-C16 alkyl; b) Reacting said plasticizer-like agent with PVC azide of formula (III) through a click reaction:wherein p is an integer comprised between 5 and 40 and n is an integer between 10 and 55 and n+p is an integer comprised between 50 and 60;c) Isolating the obtained self-plasticized PVC material of Formula (IV):(IV) , wherein n, p, q, o, R4, XI,X2 and X3 are as defined above.

2. A method according to claim 1, wherein the plasticizer-like agent is reacted with PVC azide at a temperature from about 35°C to about 45°C (e.g. 42°C).

3. A method according to claim 1 or 2, wherein the click reaction is carried out in presence of copper as catalyst.

4. A plasticizer-like agent of Formula (I):(I) wherein q is an integer selected from 0 to 14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to14; R4 is selected from H and a straight or branched Ci-Cs alkyl; XI, X2 and X3 are independently selected from H and a group of Formula (II), wherein at least one of XI to X3 is not H:wherein x is an integer selected from 3 to 10; y is an integer from 0 to 8; R1 is selected from a straight or branched C4-C16 alkyl, R2 is selected from a straight or branched C4-C16 alkyl.

5. A plasticizer-like agent according to claim 4 wherein y is 0.

6. A plasticizer-like agent according to claim 4 or 5, wherein the sum q+o is an integer from 1 to 6.

7. A plasticizer-like agent according to any one of claims 4 to 6, having a Formula (la):(la) wherein m is an integer from2 to 4 and x and R1 and R2 are as defined in claim 4.

8. A plasticizer-like agent of claim 7, wherein m is selected from 2 to 4.

9. A plasticizer-like agent of any one of claims 4 to 8 of Formula (F)(I’) wherein m is an integer from 2 to 4 and R is 2-Et- hexyl.

10. A method of preparation of a plasticizer-like agent of any one of claims 4 to 6, wherein said method comprises a Fisher esterification of a dicarboxylate compound of Formula (V) with an acid compound of Formula (VI):wherein x is an integer selected from 3 to 10, R1 is selected from a straight or branched C4-C16 alkyl, R2 is selected from a straight or branched C4-C16 alkyl; R3 is a moiety of the following formula (VII):(VH) and wherein q is an integer selected from 0 to14; o is an integer selected from 0 to 14, wherein the sum q+o is an integer from 0 to 14; X4 is selected from H, COOH and (CH2)yiCOOH; X5 is selected from H, COOH and (CH2)y2COOH; Xe is selected from H, COOH and (CH2)y3COOH, wherein at least one of X4 to Xe has a carboxylic acid group; R4 is selected from H and a straight or branched Ci-Cs alkyl and yi, yz and yz are an integer from 1 to 8.

11. A self-plasticized PVC material of Formula (IV):wherein n, p, q, o, R4,XI, X2 and X3 are as defined in any one of the preceding claims.

12. A self-plasticized PVC material according to claim 8 of Formula (IVa):wherein x, n, p, m, R1 and R2 are as defined in any one of the preceding claims.

13. A self-plasticized PVC material according to any one of claims 11 to 12, wherein m is an integer from 2 to 4.

14. A self-plasticized PVC material according to any one of claims 11 to 13, wherein at least one of R1 and R2 is optionally substituted hexyl.

15. A self-plasticized PVC material according to any one of claims 11 to 14, wherein R1 and R2 are 2-Et-hexyl.

16. A self-plasticized PVC material according to any one of claims 11 to 15, wherein said self-plasticized PVC material is a polymer selected from dl-d4:5 d3, andd4; wherein n and p are as defined in any one of the preceding claims.

17. A use of a self-plasticized PVC material according to anyone of claims 11 to 16 for the preparation of an ion-selective membrane.

18. A sensor comprising an ion-selective membrane comprising a self-plasticized PVC material according to anyone of claims 11 to 16.

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