Compatibilized polyolefin blends

Abstract

Disclosed is a compatibilized polyolefin blend containing polyethylene, polypropylene, and a pair of acid-base compatibilizers (ABCs), in which the ABCs have an acid compatibilizer and a base compatibilizer. Definitions of the components are provided. Also included are methods of modifying polyethylene and polypropylene as well as methods of compatibilizing polyolefins.

Description

BC2024.013.wan BCOT-002-WO1 1 COMPATIBILIZED POLYOLEFIN BLENDS CROSS REFERENCE TO RELATED APPLICATION

[0001] The application claims the benefit of priority to US Application Serial No. 63 / 619,505 filed on January 10, 2024, the entire content of which is incorporated by reference. GOVERNMENT SUPPORT

[0002] The invention was made with government support under Grant Numbers CHE 1955098, CHE 1944512, and CHE 2117246 awarded by the National Science Foundation. The government has certain rights in the invention. FIELD OF INVENTION

[0003] The disclosure relates to functionalizing polyolefins and compatibilizing polyolefin blends. BACKGROUND

[0004] Polyolefins, including polyethylene (PE) and isotactic polypropylene (iPP), account for approximately half of all non-fiber plastics synthesized due to their versatile mechanical properties and ease of production. See Geyer et al., Sci. Adv.2017, 3: e1700782. They are also major plastics found in recycled wastes.

[0005] Nevertheless, polyolefins are notoriously difficult to recycle due to the inherent incompatibility of their common varieties, e.g., PE and iPP. Further, they are unfeasible to separate because of their similar optical properties and densities. The mixture of PE and iPP, as often found in post-consumer plastic waste, is a brittle material with poor mechanical properties because PE and iPP are inherently immiscible. Both polyolefins remain as major challenges in plastic recycling.

[0006] Numerous strategies have been proposed to compatibilize polyolefin blends, typically by adding compatibilizers. One approach involves using block or graft co- polymers. See Eagan et al., Science 2017, 355 (6327), 814–816. While effective, the cost of these tailor-made copolymers would need to be further reduced for large-scale implementations. Alternatively, dynamic crosslinkers have been explored as reactive 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 2 compatibilizers. See Clarke et al., Nature 2023, 616 (7958), 731–739. Unfortunately, these strategies face significant limitations including use of complicated catalysts and lengthy preparation methods.

[0007] There is a need to develop a method for efficiently compatibilizing polyolefins to recycle these plastics. SUMMARY

[0008] This invention is based on an unexpected discovery of compatibilization methods for turning polyolefin waste to useful materials.

[0009] Accordingly, one aspect of this invention relates to a compatibilized polyolefin blend containing polyethylene, polypropylene, and a pair of acid-base compatibilizers (ABCs), wherein the ABCs have an acid compatibilizer and a base compatibilizer and the pair of ABCs is selected from the group consisting of: (i) the acid compatibilizer is an acid polyethylene containing polyethylene modified with a plurality of acid functional groups and the base compatibilizer is a base polypropylene containing polypropylene modified with a plurality of base functional groups; (ii) the acid compatibilizer is an acid polypropylene containing propylene modified with a plurality of acid functional groups and the base compatibilizer is a base polyethylene containing polyethylene modified with a plurality of base functional groups; and (iii) the acid compatibilizer is a first modified polyolefin and the base compatibilizer is a second modified polyolefin, in which the first modified polyolefin is a first polyolefin modified with a plurality of acid functional groups, the second modified polyolefin is a second polyolefin modified with a plurality of base functional groups, and each of the first and second polyolefins contains polyethylene and polypropylene.

[0010] The compatibilized polyolefin blend of this invention can have one or any combination of the following features:

[0011] (i) The acid or base functional groups are selected from the group consisting of a carboxyl group, a sulfonic acid group, a phosphonic acid group, a hydroxyl group, a phenol group, a thiol group, a nitro group, a borane group, an anhydride group, a carbocation group, an amine group, a pyridine group, an imidazole group, a phosphine group, an amide group, a nitrile group, an imine group, an ether group, a sulfide group, and a carbonyl group. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 3

[0012] (ii) The acid functional groups are carboxyl groups (-COOH) and the basefunctional groups are pyridine groups (or without substitutions).

[0013] (iii) The acid functional groups are derived from 4-vinylbenzoic acid such as and the base functional groups are derived from 4-vinylpyridine

[0014] (iv) Each of the acid and base compatibilizers, independently, has a degree of functionality of 0.1 to 10 mol%.

[0015] (v) The molar ratio of the acid functional groups and the base functional groups is 1:4 to 4:1, preferably 1:2 to 2:1, and more preferably 1:1.2 to 1.2:1.

[0016] (vi) The compatibilized polyolefin blend contains 5-94 wt% of polyethylene, 94-5 wt% of the polypropylene, 0.5-5 wt% of the acid compatibilizer, and 0.5-5 wt% of the base compatibilizer.

[0017] (vii) Polyethylene is high-density polyethylene, very low-density polyethylene, linear low-density polyethylene, or any combination thereof.

[0018] (viii) Polypropylene is isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, or any combination thereof.

[0019] Another aspect of this invention relates to a compatibilized polyolefin blend containing polyethylene, polypropylene, a modified polyethylene, and a modified polypropylene, wherein the modified polyethylene is polyethylene modified with a first group, the modified polypropylene is a polypropylene modified with a second group, the first group is one of an acid group and a base group, and the second group is the other of the acid group and the base group. In one embodiment, the first group is one of carboxyl and pyridinyl, the second group is the other of carboxy and pyridinyl, the molar ratio of the first group and the second group is 1:4 to 4:1, preferably 1:2 to 2:1, and more preferably 1:1.2 to 1.2:1; and the compatibilized polyolefin blend contains 5-94 wt% of polyethylene, 94-5 wt% of the polypropylene, 0.5-5 wt% of the modified polyethylene, and 0.5-5 wt% of the modified polypropylene.

[0020] A preferred compatibilized polyolefin blend contains polyethylene, polypropylene, the modified polyethylene, and the modified polypropylene, in which the 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 4 modified polyethylene having a polyethylene backbone and acid or base functional groups, and the modified polypropylene having a polypropylene backbone and base or acid functional groups, provided that when the modified polyethylene has acid functional groups, the modified polypropylene has base functional groups, and vice versa. Typically, the acid functional groups are carboxyl and the base functional groups are pyridyl. Examples of the acid functional group include those derived from 4-vinylbenzoic acid, fumaric acid, dimethyl fumarate, maleic acid, and dimethyl maleate. Examples of the base functional group include those derived from 4-vinylpyridine.

[0021] Exemplary modified polyethylene and polypropylene polymers can have a formula shown below.

[0022] In the modified polyethylene and polypropylene above, each functional group is randomly connected to the backbone through a functionalization reaction. The above modified polymer each is modified by one of the following groups containing carboxyl (- COOH) as the acid functional group and pyridyl (-C5H4N) as the base functional group.

[0023] As shown above, each modified polyethylene has a polyethylene backbone and a plurality of functional groups randomly attached to the backbone. Functional groups shown above are a dimethyl succinate group, a succinic acid group, pyridine-4-ylethylene, and 4- carboxyphenethylene. A dimethyl succinate group is derived from dimethyl maleate obtained by irradiating a mixture of polyethylene and dimethyl maleate in the presence of a photocatalyst described herein. The dimethyl succinate group can further be converted to succinic acid group to obtain succinic acid modified polyethylene. Alternatively, succinic acid modified polyethylene can be prepared by irradiating a mixture of polyethylene and 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 5 maleic acid in the presence of the photocatalyst. Pyridine-4-ylethylene modified polyethylene can be prepared by irradiating a mixture of polyethylene and 4-vinylpyridine in the presence of the photocatalyst. 4-Carboxyphenethylene modified polyethylene can be prepared by irradiating a mixture of polyethylene and 4-vinylbenzoic acid in the presence of the photocatalyst.

[0024] In the modified polyethylene represented by the formulas above, the polyethylene backbone has m+1 non-modified ethylene repeat units and n modified ethylene repeat units. The total ethylene repeat units (m + n + 1) can be 200-5000. M can be 198 to 4949 (e.g., 250 to 4000, 300 to 3500, 400 to 3000, and 500 to 2000). N can be 1 to 500 (e.g., 2 to 400, 5 to 300, 10 to 200, and 20 to 150). The degree of functionality, n / (m + n + 1), is measured as the percentage of functionalized repeat units in a polymer backbone. In the above example, the degree of functionality is 0.1% to 10% (e.g., 0.2% to 8%, 0.3% to 6%, 0.4% to 5%, and 0.5% to 2%).

[0025] Each modified polypropylene has a polypropylene backbone and a plurality of functional groups randomly attached to the backbone. Functional groups on polypropylene shown above are a dimethyl succinate group, a succinic acid group, pyridine-4-ylethylene, and 4-carboxyphenethylene. Dimethyl succinate modified polypropylene can be obtain by irradiating a mixture of a mixture of polypropylene and dimethyl maleate in the presence of the photocatalyst. The dimethyl succinate group can further be converted to succinic acid group to obtain succinic acid modified polypropylene. Alternatively, succinic acid modified polypropylene can be prepared by irradiating a mixture of polypropylene and maleic acid in the presence of the photocatalyst. Pyridine-4-ylethylene modified polypropylene can be prepared by irradiating a mixture of polypropylene and 4-vinylpyridine in the presence of the photocatalyst. 4-Carboxyphenethylene modified polypropylene can be prepared by irradiating a mixture of polypropylene and 4-vinylbenzoic acid in the presence of the photocatalyst.

[0026] In the modified polypropylene represented by the formulas above, the polypropylene backbone has x+1 non-modified propylene repeat units and y modified propylene repeat units. The total propylene repeat units (x + y + 1) can be 100-5000. X can be 98 to 4949 (e.g., 150 to 4000, 200 to 3000, and 500 to 2000). Y can be 1 to 500 (e.g., 2 to 400, 5 to 300, 10 to 200, and 20 to 100). The degree of functionality, y / (x + y + 1), is measured as the percentage of functionalized repeat units in a polymer backbone. In the 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 6 above example, the degree of functionality is 0.1% to 10% (e.g., 0.2% to 8%, 0.3% to 6%, 0.4% to 5%, and 0.5% to 2%).

[0027] Also within the scope of this invention is a method of compatibilizing polyolefins including the steps of: (i) providing a first modified polyolefin containing an acid functional group, in which the first modified polyolefin is prepared by irradiating a first mixture containing a first polyolefin, a first photocatalyst, and a first modifier to obtain the first modified polyolefin, and the first modifier contains a C=C double bond and the acid functional group; (ii) providing a second modified polyolefin containing a base functional group, in which the second modified polyolefin is prepared by irradiating a second mixture containing a second polyolefin, a second photocatalyst, and a second modifier to obtain the second modified polyolefin, and the second modifier contains a C=C double bond and the base functional group; and (iii) mixing the first polyolefin, the first modified polyolefin, the second polyolefin, and the second modified polyolefin to obtain a compatibilized polyolefin blend.

[0028] The method of compatibilizing polyolefins can have one or any combination of the following features:

[0029] (i) Each of the first and second polyolefins, independently, is polyethylene, polypropylene, or a combination thereof.

[0030] (ii) Each of the first and second polyolefins, independently, is high-density polyethylene, low-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, or any combination thereof.

[0031] (iii) Polyethylene is high-density polyethylene having 200-5000 repeat units of ethylene (-CH2-CH2-).

[0032] (iv) Polypropylene is an isotactic polypropylene having 100-5000 repeat units of propylene (-CH(CH3)-CH2-).

[0033] (v) The compatibilized polyolefin blend contains 5-94 wt% of the first polyolefin, 0.5-5 wt% of the first modified polyolefin, 94-5 wt% of the second polyolefin, and 0.5-5 wt% of the second modified polyolefin.

[0034] (vi) The weight ratio of the first modified polyolefin and the second modified polyolefin is in the range of 1 : 10 to 10 : 1.

[0035] (vii) Each of the first and second photocatalysts, independently, is an anthraquinone or a decatungstate salt. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 7

[0036] (viii) Each of the first and second photocatalysts, independently, is 2- chloroanthraquinone, anthraquinone, anthraquinone-2-sulfonate, anthraquinone-2-carboxylic acid, 1-chloro-anthraquinone, 1,5-dichloroanthraquinone, 1,8-dichloroanthraquinone, 1- hydroxyanthra-quinone, 1,2-dihydroxyanthraquinone, 1,8-dihydroxyanthraquinone, 1- aminoanthraquinone, 1,5-diaminoanthraquinone, sodium decatungstate (NaDT), tetraoctylammonium decatungstate (TOADT), tetrabutylammonium decatungstate (TBADT), or tetraphenylphosphonium decatungstate (TPPDT).

[0037] (ix) Each of the first and second photocatalysts is 2-chloroanthraquinone.

[0038] (x) Each of the first and second photocatalysts is 2-chloroanthraquinone or TOADT.

[0039] (xi) The acid or base functional group is a carboxyl group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, a phenol group, a thiol group, a nitro group, a borane group, an anhydride group, a carbocation group, an amine group, a pyridine group, an imidazole group, a phosphine group, an amide group, a nitrile group, an imine group, an ether group, a sulfide group, or a carbonyl group.

[0040] (xii) The first modifier is 4-vinylbenzoic acid, 2-vinylbenzoic acid, 3-vinyl- benzoic acid, 1,2-bis(4-carboxyphenyl)ethene, styrene-4-sulfonic acid, maleic acid, fumaric acid, maleic anhydride, dimethyl maleate, dibutyl maleate, diallyl maleate, 2-butenoic acid, cinnamic acid, 3-(pyridin-4-yl)acrylic acid, vinyl sulfonic acid, vinyl phosphonic acid, diethylstilbestrol, benfotiamine, GDC-0810 (i.e., brilanestrant), mucochloric acid, tetra(p- hydroxyphenyl)-ethylene, 4-(1,2,2-triphenylvinyl)phenol, dihydroxyfumaric acid, mucobromic acid, endoxifen, 2,3,3-trichloroacrylic acid, clomiphene, 2-cyano-3-methylbut- 2-enoic acid, or isopropylidenemalonic acid.

[0041] (xiii) The second modifier is 4-vinylpyridine, 2-vinylpyridine, 3-vinylpyridine, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(2-pyridyl)ethene, 1,2-bis(3-pyridyl)ethene, 4-styrylpyride, 4-[2-(4-nitrophenyl)ethenyl]-pyridine, methyl 3-(pyridin-4-yl)acrylate, 4-vinyl-piperidine, 3- vinyl-piperidine, 2-vinyl-piperidine, t-butyl N-vinylcarbamate, 1-vinylimidazole, 2-vinyl- imidazole, 4-vinylaniline, 3-vinylaniline, 2-vinylaniline, tamoxifen, teriflunomide, ospemifene, diaminomaleonitrile, 2,3-diaminomaleonitrile, [bis(methylthio)methylene]- malononitrile, (1-ethoxyethylidene)malono-nitrile, ethyl 2-cyano-3,3-di(methylsulfanyl)- acrylate, octocrylene, ethenetetracarbonitrile, (E)-ethyl 2-cyano-3-ethoxybut-2-enoate, isopropylidenemalononitrile, etocrylene, 1,1,3-tricyano-2-amino-1-propene, benfotiamine, GDC-0810, endoxifen, clomiphene, 1-chloro-1-(dimethylamino)-2-methyl-1-propene, diethyl 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 8 isopropylidenemalonate, diisopropyl azodicarboxylate, acrylonitrile, 1,2-dicyanoethylene, methyl vinyl ketone, 4-penten-3-one, 4-vinylbenzyl chloride, 3-vinylbenzyl chloride, 2- vinylbenzyl chloride, or 1,1,2,2-tetrachloroethylene. Among the modifiers above, Lewis bases are included, such as di-isopropyl azodicarboxylate, acrylonitrile, 1,2-dicyanoethylen, methyl vinyl ketone, and 4-penten-3-one. Further, vinylbenzyl chlorides can be readily converted to bases through replacement reactions to change chloride to hydroxyl.

[0042] (xiv) The first modifier is 4-vinylbenzoic acid.

[0043] (xv) The second modifier is 4-vinylpyridine.

[0044] (xvi) Each of the first and second photocatalysts is present at a level of 0.001 mol% to 3 mol% relative to the repeat units of first or second polyolefin, preferably at 0.01 mol% to 1 mol%, and more preferably at 0.1 mol% to 0.3 mol%.

[0045] (xvii) The first modifier is present at a level of 1 mol% to 100 mol% relative to the repeat units of the first polyolefin, preferably at 5 mol% to 50 mol%, and more preferably at 10 mol% to 30 mol%; and the second modifier is present at a level of 1 mol% to 100 mol% relative to the repeat units of the second polyolefin, preferably at 5 mol% to 50 mol%, and more preferably at 10 mol% to 30 mol%.

[0046] (xviii) The irradiating step on either the first or second polyolefin is performed in a solvent selected from the group consisting of chlorobenzene, benzonitrile, naphthalene, diphenyl ether, and bromobenzene.

[0047] (xix) The irradiating step on either the first or second polyolefin is performed absent of a solvent.

[0048] (xx) The irradiating step on either the first or second polyolefin is performed at a temperature of 100 ºC to 250 ºC, preferably at 105 ºC to 150 ºC, and more preferably 110 ºC to 130 ºC.

[0049] (xxi) The irradiating step on either the first or second polyolefin utilizes a light having a wavelength of 200 nm to 420 nm, preferably 250 nm to 410 nm, and more preferably 300 nm to 395 nm.

[0050] (xxii) The irradiation step on either the first or second polyolefin is performed for 10 minutes to 50 hours.

[0051] (xxiii) The first or second modified polyolefin has a degree of functionality of 0.1 to 10 mol% relative to the repeat units of the first or second polyolefin. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 9

[0052] (xxiv) The first polyolefin is one of polyethylene and polypropylene, the second polyolefin is the other of polyethylene and polypropylene, the first modifier is 4-vinylbenzoic acid, and the second modifier is 4-vinylpyridine.

[0053] After the modification step, the modified polyolefin can undergo further modification to add an acid or base functional group through convention reactions known to a skilled person in the art following known procedures.

[0054] Still within the scope of the invention is a method of functionalizing a polyolefin including the step of irradiating a mixture containing a polyolefin, a photocatalyst, and a modifier to obtain a modified polyolefin, wherein the polyolefin is polyethylene, polypropylene, or a combination thereof; and the modifier contains (i) a C=C double bond and (ii) an acid or base functional group. The modifiers, functional groups, and the photocatalyst are described above.

[0055] The details of the invention are set forth in the definitions and the detailed description below. Other features, objects, and advantages of the invention will be apparent from the following actual examples and claims. DETAILED DESCRIPTION

[0056] A method of this invention compatibilizes polyolefins utilizing noncovalent interactions, such as those formed between acid and base functional groups. Acid or base modified polyolefins, namely, acid-base compatibilizers (ABCs), are synthesized through direct polyolefin modification, with acid or base units randomly installed onto polyolefin backbones via facile hydrogen atom transfer (HAT)-initiated C−H activation, followed by Giese radical addition reactions.

[0057] ABCs contain at least two modified polyolefins, e.g., a first modified polyolefin containing an acid functional group and a second modified polyolefin containing a base functional group. When the first modified polyolefin is mixed with the second modified polyolefin, they form close pairs through acid–base interactions.

[0058] The first modified polyolefin is prepared by irradiating a first polyolefin and a first modifier in the presence of a first photocatalyst with or without a solvent. The second modified polyolefin is prepared the same way using a second polyolefin, a second modifier, and a second photocatalyst. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 10

[0059] The first polyolefin can be one of polyethylene (PE) and isotactic polypropylene (iPP), and the second polyolefin can be the other of PE and iPP. Alternatively, both the first polyolefin and the second polyolefin are the same, e.g., a blend of PE and iPP in any ratio or as obtained from a recycled waste.

[0060] As an illustration, PE is functionalized with an acid functional group to obtain a modified PE and iPP is functionalized with a base functional group to become a modified iPP. The modified PE and iPP, acting as ABCs, are added to a blend containing non-modified PE and iPP. The PE acid groups and the iPP base groups form acid-base pairs thereby compatibilizing PE and iPP, resulting in a material having improved properties. Further the PE segments of the modified PE co-crystallize with non-modified PE. Similarly, the iPP segments of modified iPP co-crystallize with non-modified iPP. Cohesive interactions occur at the interface through acid–base interactions between non-modified PE and iPP. As a result, the interfacial tension between PE and iPP and domain sizes are minimized, generating compatibilized blends. In one example below, an 82-fold increase in elongation at break (εb) has been achieved with the addition of 10 wt% of ABCs that are modestly functionalized using the method of this invention (1.4% installation of acid onto high-density PE (HDPE) and 1.4% installation of base onto iPP).

[0061] As another illustration, PE is functionalized with a base functional group to obtain a modified PE and iPP is functionalized with an acid functional group to become a modified iPP. The modified PE and iPP, acting as ABCs, are added to a blend containing non-modified PE and iPP.

[0062] In a preferred embodiment, a first plastic blend containing both PE and iPP is functionalized with an acid functional group to obtain a first modified polyolefin and a second plastic blend containing both PE and iPP is functionalized with a base functional group to obtain a second modified polyolefin. The first polyolefin blend can be the same as or different from the second polyolefin blend. Preferably, they are the same. The first modified polyolefin and the second modified polyolefin, acting as ABCs, are added to a blend containing PE and iPP (e.g., the first plastic blend, the second plastic blend, or a combination thereof). As described above, PE and iPP in the resultant mixture are compatibilized to provide a material with improved properties. Indeed, an example below demonstrates that a polyolefin blend (namely, a post-consumer plastic mixture) by directly functionalizing the blend, has achieved a high degree of compatibilization. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 11

[0063] Modified polyolefins can be prepared from chemicals commercially available and of low-cost. The modification reaction is a one-step functionalization with high atom efficiency. Large-scale production can be implemented without technical difficulties. More specifically, a polyolefin is functionalized with the aid from a photocatalyst, e.g., 2- chloroanthraquinone (2-ClAQ). Not to be bound by any theory, the modification reaction is illustrated in Scheme I below. As a first step, a photocatalyst (shown as PC, e.g., 2-ClAQ) is photoexcited upon illumination to generate a species (PC*) featuring a highly electrophilic center, which abstracts an H atom from an electron-rich polyolefin (R-H) to obtain a nucleophilic carbon-centered polyolefin radical (R·) and a hydrogenated photocatalyst intermediate H-PC˙. A first or second modifier (CH2=CH—FG) acts as a Giese acceptor containing a C=C double bond and an acid or base functional group (FG) as an electron withdrawing group. The modifier reacts with the nucleophilic carbon-centered polyolefin radical via a conjugated addition to obtain a conjugated intermediate (R-CH2—C˙H—FG). A modified polyolefin (R-CH2—CH2—FG) is produced by hydrogen back-donation from H- PC˙, simultaneously regenerating PC.

[0064] Suitable photocatalysts are highly specific in activating C−H bonds in polyolefins without inducing significant side reactions and are compatible with acid / base modifiers. Preferred photocatalysts are those that neither leave a residue in the modified polyolefin nor compromise the polyolefin mechanical properties, aside from reactivity and availability. A useful photocatalyst is 2-chloroanthraquinone (2-ClAQ), a small molecule HAT photocatalyst. Upon illumination, a photoexcited 2-ClAQ species contains a highly electrophilic oxygen center, initiating the chain reactions as describe in Scheme 1 below. Scheme I4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 12

[0065] The modification reaction is a one-step process generating a series of reactive species and starting a chain of subsequent reactions as shown above.

[0066] Polyolefins suitable for functionalization include high-density polyethylene, low- density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, and any combination thereof.

[0067] A high-density polyethylene (HDPE) finds many applications due to its toughness, melt strength, and environmental stress cracking resistance. See US Patent Nos 10,787,563 and 11,447,620.

[0068] HDPE can have a density of 945 kg / m3or greater, e.g., 945 kg / m3to 960 kg / m3, 950 kg / m3to 960 kg / m3, 946 kg / m3to 951 kg / m3, 947 kg / m3to 951 kg / m3, 948 kg / m3, 953 kg / m3, and 957 kg / m3) and can have one or more ethylene polymers such as an ethylene polymer (A) having a density of at least 968 kg / m3(e.g., at least 970 kg / m3and at least 971 kg / m3) in an amount ranging from 45-55% by weight and an ethylene polymer (B) having a density lower than the density of polymer A. The high-density polyethylene can have a complex viscosity at a shear rate of 0.01 rad / s ranging from 200 to 450 kPa·s, a melt index MI2of at least 1 g / 10 minutes, or a MI5of 0.1 to 0.5 g / 10 min. MI5and MI2can be measured according to ISO1133 at a temperature of 190° C under loads of 21.6 kg, 5 kg and 2.16 kg.

[0069] Density of the polyethylene was measured according to ISO 1183-1 (Method A) and the sample plaque was prepared according to ASTM D4703 (Condition C) where it was cooled under pressure at a cooling rate of 15° C. / min from 190° C. to 40° C.

[0070] A low-density polyethylene (LDPE) is useful for packaging materials, containers, films, tubing, caps, closures, and cable coatings as it is stretchy and strong. LDPE has a density lower than 945 kg / m3(e.g., 850-945 kg / m3, 850-909 kg / m3very low-density polyethylene VLDPE, 909-930 kg / m3linear low-density polyethylene LLDPE, and 930-945 kg / m3medium low-density polyethylene MDPE). See US Patent No.10,262,265 and 12,110,371.

[0071] Polyethylene has repeat units of ethylene (-CH2-CH2-), usually in the amount of up to 200,000 (e.g., 150-10,000 and 200-5000). Its molecular weight is in the range of 198 to 6,500,000. HDPE typically has a molecular weight of 100,000 to 250,000. Linear polyethylene usually has a molecular weight of 200,000 to 500,000.

[0072] Isotactic polypropylene (iPP) has methyl groups oriented on one side of the carbon backbone resulting a great degree of crystallinity and a stiff material resistant to creep. It is a thermoplastic polymer known for strength, thermal stability, chemical resistance, and 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 13 cost-effectiveness. It has a molecular weight ranging from 4,000 to 200,000 g / mol (e.g., 10,000 to 40,000 g / mol) with 100 to 5000 (e.g., 150 to 3000 and 200-1000) repeating units of propylene (-CH(CH3)-CH2-). Isotactic polypropylene is the most widely used polypropylene.

[0073] Syndiotactic polypropylene has methyl groups oriented in an alternating pattern on opposite sides of the carbon backbone. It is useful as an insulating material for high voltage cables. It has a molecular weight ranging from 1,000 to 200,000 g / mol (e.g., 100,000 to 200,000 g / mol) with 100 to 5000 (e.g., 150 to 3000 and 200-1000) repeating units of propylene (-CH(CH3)-CH2-).

[0074] Atactic polypropylene is a rubbery, amorphous thermoplastic material useful in adhesives, insulation, anti-corrosion, and rubber extender. The methyl groups are arranged randomly on either side of the carbon backbone. It can have 100 to 10,000 repeat units of propylene (-CH(CH3)-CH2-).

[0075] Polyolefins are modified with a degree of functionality ranging from 0.1 mol% to 50 mol% (e.g., 0.15 to 25 mol%, 0.2 to 15 mol%, 0.3 to 10 mol%, 0.5 to 6 mol%, 1.5 mol%, 2.5 mol%, 3 mol%, 4 mol%, 5 mol%, and 6 mol%), with all mol% compared to the repeat unit of polyolefins. The degree of functionality is determined by proton nuclear magnetic resonance (1H NMR) spectra.

[0076] UV light is applied (e.g., ^ = 365 nm; Power: 485 mW / cm2) as an energy input in the modification reaction. A skilled person in the art would be able to determine the light source, wavelength, and energy output taking into consideration of catalyst, substrate, scale, solvent, etc.

[0077] The time needed to complete the PDH reaction depends on several factors, e.g., light source, wavelength, light energy output, concentration of the catalyst, concentration of modifiers, temperature, solvent, scale of production, etc.

[0078] Certain terminology is used in the following description for convenience only and is not limiting.

[0079] A range expressed as being between two numerical values, one as a low endpoint and the other as a high endpoint, includes the values between the numerical values and the low and high endpoints. Embodiments herein include subranges of a range herein, where the subrange includes a low and high endpoint of the subrange selected from any increment within the range selected from each single increment of the smallest significant figure, with the condition that the high endpoint of the subrange is higher than the low endpoint of the subrange. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 14

[0080] Further embodiments herein include replacing one or more “including” or “comprising” in an embodiment with “consisting essentially of” or “consisting of.” “Including” and “comprising,” as used herein, are open ended, include the elements recited, and do not exclude the addition of one or more other elements. “Consisting essentially of” means that addition of one or more element compared to what is recited is within the scope, but the addition does not materially affect the basic and novel characteristics of the combination of explicitly recited elements. “Consisting of” refers to the recited elements, but excludes any element, step, or ingredient not specified.

[0081] The words “a” and “one,” as used in the claims and in the corresponding portions of the specification, are defined as including one or more of the referenced items unless specifically stated otherwise. This terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. The phrase “at least one” followed by a list of two or more items, such as “A, B, or C” or “A, B, and C” means any individual one of A, B or C as well as any combination thereof.

[0082] The term “acid” includes Lewis acids and Brønsted acids. The term “Lewis acid” refers to a substance which, in solution, is capable of generating a cation or combining with an anion, or a molecule which is capable of accepting a pair of electrons. IUPAC defines “Lewis acid” as a molecular entity (and the corresponding chemical species) that is an electron-pair acceptor and therefore able to react with a Lewis base to form a Lewis adduct, by sharing the electro pair furnished by the Lewis base. Examples include ketones, aldehydes, BF3, PF5, SbF5, AsF5, and their organic derivatives such as organoboranes and silicates. The term “Brønsted acid” refers to a protic or proton-donating species. Examples include carboxylic acids (R-COOH), phenols (Ph-OH), sulfonic acids (R-SO3H), and phosphoric acids (e.g., R-P(O)(OH)2and R-P(O)(OR’)OH), in which each of R and R’, independently, is C1-C20 alkyl, C1-C20 heteroalkyl, C2-C20 alkenyl, C2-C20 alkynyl, C3-C20 cycloalkyl, 3- to 20-membered heterocycloalkyl, aryl, aralkyl, heteroaryl, or heteroaralkyl.

[0083] The term “Lewis base” refers to a substance which, in solution, is able to generate an anion or combine with a cation, or a molecule or ion that is capable of donating a pair of electrons. Useful classes of Lewis bases include, but are not limited to, ammonia, amines, pyridines, phosphines (e.g., trimethyl phosphine), ethers, ketones (e.g., acetone, butanone, methyl vinyl ketone, and 4-penten-3-one), sulfates, ethyne, ethene, benzenes, thiophenes, quinuclidine, and nitriles (e.g., acetonitrile and acrylonitrile). The term “Brønsted base” 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 15 refers to a substance is capable of accepting a proton. Examples include amines such as pyridines, piperidines, imidazoles, and anilines.

[0084] The term “salt” refers to those salts which are derived from suitable inorganic and organic acids and bases. Salts derived from appropriate bases include alkali metal, alkaline earth metal, ammonium and N+(C1-6 alkyl)4−salts. Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, magnesium, and the like. Further salts include, when appropriate, ammonium, quaternary ammonium, and amine cations.

[0001] The term “alkyl” as used herein, means a straight or branched chain, monovalent or divalent hydrocarbon. An alkyl group herein may have from 1 to 30 carbon atoms (e.g., 1- 25, 2-20, 3-16, 5-8, 1-6, and 1-4) unless otherwise specified. An alkyl group may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 carbon atoms, or a number of carbon atoms in a range from a first of the foregoing values to a second of the foregoing values, where the first and second values selected are any two of the foregoing values and the first value is less than the second. Examples include methyl (Me), methylene, ethyl, ethylene, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl.

[0085] The term “alkenyl” refers to a linear or branched monovalent or divalent hydrocarbon moiety that contains at least one double bond.

[0086] The term “alkynyl” refers to a linear or branched monovalent or divalent hydrocarbon moiety that contains at least one triple bond.

[0087] The term “cycloalkyl” refers to a saturated or unsaturated, cyclic, nonaromatic, monovalent or divalent hydrocarbon moiety, such as cyclohexyl and cyclohexylene.

[0088] The term “heterocycloalkyl” refers to a nonaromatic 5–8 membered monocyclic, 8–12 membered bicyclic, or 11–14 membered tricyclic, monovalent or divalent ring system having one or more heteroatoms (e.g., O, N, P, and S). Examples include aziridinyl, azetidinyl, pyrrolidinyl, dihydrofuranyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydrothiophenyl, tetrahydro-2-H-thiopyran-1,1-dioxidyl, piperazinyl, piperidinyl, morpholinyl, imidazolidinyl, azepanyl, dihydrothiadiazolyl, dioxanyl, and quinuclidinyl. Both “cycloalkyl” and “heterocyclyl” also include fused, bridged, and spiro ring systems. They further include substituted groups such as halocycloalkyl and haloheterocyclyl.

[0089] The term “aryl” herein refers to a monocyclic, bicyclic or tricyclic aromatic, monovalent or divalent ring system. Examples include phenyl, biphenyl, 1‑ or 2-naphthyl, 1,2-dihydronaphthyl, 1,2,3,4-tetrahydronaphthyl, indenyl, and indanyl. Aryl can be unsubstituted or substituted with alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 16 heteroaryl, amino, ether, ester, and the like. The term “aralkyl” refers to alkyl substituted with aryl, i.e., aryl-alkyl.

[0090] The term "heteroaryl” herein refers to an aromatic monocyclic, bicyclic, tricyclic, and tetracyclic ring system having one or more heteroatoms (such as O, S or N). Examples include pyridinyl, pyrimidinyl, quinolinyl, isoquinolinyl, indolyl, benzimidazolyl, benzoxazolyl, benzothiophenyl, benzofuranyl, pyrazolyl, triazolyl, oxazolyl, thiadiazolyl, tetrazolyl, oxazolyl, isoxazolyl, carbazolyl, furyl, imidazolyl, thienyl, thiazolyl, and benzothiazolyl. The term “heteroaralkyl” refers to alkyl substituted with heteroaryl, i.e., heteroaryl-alkyl.

[0091] The term “amino” refers to primary (NH2), secondary (-NH-), tertiary ( ), orquaternary ( ) amine group bonding to or being included in one or more of C1-C30(e.g., C2-C20and C4-C16) alkyl, C1-C30(e.g., C2-C20and C4-C16) heteroalkyl, aryl, or heteroaryl moieties. Examples include alkyl amino, dialkyl amino, alkenyl amino, etc. Aliphatic amino examples include C1-C30 alkyl amino, C2-C30 alkenyl amino, C2-C30 alkynyl amino, and C3-C30cycloalkyl. C1-C30heterocycloalkyl amino is an example of heteroaliphatic amino.

[0092] The term “ketone” refers to R-C(O)-R”, in which each of R and R”, independently, is (e.g., C2-C20 and C4-C16) alkyl, C1-C30 (e.g., C2-C20 and C4-C16) heteroalkyl, aryl, or heteroaryl.

[0093] The term “carbonyl” refers to -C(O)-R”, in which R” is defined above.

[0094] The term “carboxylate” refers to -O-C(O)-R” or -C(O)-O-R”, in which R” is define above.

[0095] The term “halo” refers to H, F, Cl, Br, or I.

[0096] The term “heteroatom” refers to an atom that is not C or H, such as O, N, S, and P.

[0097] Alkyl, heteroalkyl, alkenyl, alkynyl, cycloalkyl, amino, carbonyl, carboxylate, carbamate, aryl, aralkyl, sulfonic, and phosphoric mentioned herein include both substituted and unsubstituted moieties, unless specified otherwise. Examples of a substituent include deuterium (D), hydroxyl (OH), halo (e.g., F and Cl), amino (NH2), cyano (CN), nitro (NO2), alkyl, alkenyl, alkynyl, alkoxy, cycloalkyl, acylamino, alkylamino, aminoalkyl, haloalkyl (e.g., trifluoromethyl), heterocyclyl, alkoxycarbonyl, amido, carboxyl (COOH), alkanesulfonyl, alkylcarbonyl, alkenylcarbonyl, carbamido, carbamyl, carboxyl, thioureido, 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 17 thiocyanato, sulfonamido, aryl, arylamino, aralkyl, and heteroaryl. All substitutes can be further substituted.

[0098] Without further elaboration, it is believed that one skilled in the art can, based on the above description, utilize the present invention to its fullest extent. The following specific examples are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

[0099] All publications, including patent documents, cited herein are incorporated by reference in their entirety. EXAMPLES

[0100] Among the modifiers described above, 4-vinylbenzoic acid (v-BA), maleic acid (MA), fumaric acid (FA), cinnamic acid (CA), dimethyl maleate (DMM), 4-vinylpyridine (v- Py), 4-vinylbenzyl chloride (v-BC), and methyl 3-(pyridin-4-yl)acrylate (MPA) were used in the exemplary functionalization reactions below. A typical reaction involved 0.115 mol% of 2-ClAQ (or 0.23 mol% of TOADT), 10 mol% of v-BA (or 20 mol% of MA, FA, CA, DMM, v-Py, v-BC or MPA), with all mol% compared to the repeat unit of polyolefins), and PE or iPP in chlorobenzene (PhCl) with 365 nm or 395 nm light irradiation at 110 °C. With predetermined reaction times, functionality degrees ranging from 0.3 mol% to 5.8 mol% were obtained.

[0101] When HDPE was modified with v-BA, the signals of alkenes were negligible, indicating that the β-scission side reactions were minimum under the reaction conditions. When iPP was modified with v-Py, β-scission was also negligible.

[0102] Thermogravimetric analysis (TGA) indicated that the functionalized polyolefins maintained high thermal stability compared to their virgin counterparts. The differential scanning calorimetry (DSC) measurements showed that the introduction of a small portion of functional groups had little impact on the melting temperatures and crystallization temperatures. Additionally, the semicrystalline structures and features of HDPE and iPP remained intact after modification with benzoic acid (BA) and pyridine (Py), as evidenced by their wide-angle X-ray scattering (WAXS) profiles. All characterization results demonstrated that the modified polyolefins exhibited thermal and physical properties similar to non- modified polyolefins.

[0103] Modified HDPE / iPP mixtures were used to compatibilize HDPE / iPP blends. BA and Py functional groups interact with each other to form acid-base pairs. Due to the 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 18 relatively small difference in pKa values for BA and Py (ΔpKa ≈ 1.77), an un-ionized H- bonding interaction was anticipated and confirmed by Fourier-transform infrared spectroscopy (FTIR) analysis. A uniform mixture of HDPE-BA and iPP-Py with the same molar amount of BA and Py functional groups as ABCs was prepared through dissolution and reprecipitation, whose FTIR spectrum was compared with those of the individual components. The C=O stretch in the mixture shifted from 1693 cm–1 to 1699 cm–1, indicating the un-ionized H bond formation between BA and Py moieties. The interaction observed with a small portion of acid and base in the polymers supported their functionality in compatibilizing HDPE / iPP blends. In an example, a specific amount of ABCs (a mixture of 1.4%-HDPE-BA and 1.4%-iPP-Py) was added to a polyolefin blend containing 70 wt% HDPE and 30 wt% iPP, with this mixture representing typical polyolefin municipal waste. The PE / iPP blend without ABCs was used as a comparative sample. It lost the original ductility and exhibited poor mechanical properties (εb = 21%). With the addition of 5 wt% of ABCs, the mechanical properties of the blend improved significantly with an εb of 52%. Strikingly, when the amount of ABCs increased to 10 wt%, a remarkable 82-fold enhancement in ductility (εb = 1730%) was achieved. The effective compatibilization of polyolefin blends with the addition of ABC was further illustrated by the reduction of iPP grain size, as observed in the high-angle annular dark-field scanning transmission spectroscopy (HAADF-STEM) images. The average radii of iPP grains were reduced from 2.65 µm to 1.13 µm with 5 wt% ABC and to 0.57 µm with 10 wt% ABCs.

[0104] Moreover, the acid–base compatibilization was readily applied to real-world mixed plastic waste. Commonly used chemical containers made of HDPE (hereafter denoted as r-PE, where r represents recycled) and centrifuge tubes made of iPP (denoted as r-iPP) were cleaned, cut into pieces, and mechanically tested. The blend of r-PE and r-iPP (70:30) exhibited an εb of 60%. The average grain size of r-iPP was 0.98 µm. With the addition of 10 wt% ABCs, the tensile properties significantly improved, showing a 17-fold increase in εb (1011% versus 60%). The average radius of iPP droplets was reduced, strongly supporting the improved compatibilization in post-consumer polyolefin blends. The reduced domain sizes and stress transfer between phases were evidenced by scanning electron microscopy (SEM) images of the fractured blend surfaces for both pure and post-consumer polyolefin blends. It has been demonstrated that the introduction of ABCs of this invention restored ductility to the polyolefin blends, promising the reusage of recycled polyolefins. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 19

[0105] HDPE / iPP blends were directly functionalized and compatibilized. Two batches of a HDPE / iPP blend were separately functionalized, the first batch with v-BA and the second with v-Py. Not to be bound that any theory, either v-BA or v-Py modifies both HDPE and iPP in the same batch due to the HAT-initiated modification process. This is consistent with the ductility results. The two batches respectively functionalized with BA and Py were mixed with the same molar amount of functional groups. A surprising εb increase of 857% was observed, representing a 41-fold enhancement compared to the HDPE / iPP blend without modifications. The iPP domain sizes observed in the compatibilized blends were significantly reduced in comparison to neat HDPE / iPP blends, which was corroborated by the SEM images of the fractured blend surfaces. Significantly, the modification reactions were effectively applied to the post-consumer polyolefin blends without requiring further treatment or purification, aside from minimum washing to remove contaminants. This result demonstrates the practical applicability of the methods of this invention for direct utilization in processing real-world plastic waste. General Materials and Methods

[0106] All chemicals purchased from commercial sources were used without further purification unless otherwise stated. High-density polyethylene (HDPE, melt index 2.2 g / 10 min), low-density polyethylene (LDPE, melt index 25 g / 10 min), and isotactic polypropylene (iPP, Mn~5k, 67k, and 97k) were purchased from MilliporeSigma (Burlington, MA). All iPP polymers refer to 97k-iPP unless otherwise stated. 2-Chloroanthraquinone (2-ClAQ, 99.0+%), 4-vinylpyridine (v-Py, 96%, low polymer, stabilized with 100 ppm hydroquinone), chlorobenzene (ACS, 99.5%), and N,N-dimethylformamide (ACS, 99.8+%) were purchased from Fisher Scientific (Hampton, NH)).4-Vinylbenzoic acid (v-BA, 98%) was obtained from Ambeed (Arlington Heights, IL).

[0107] High-temperature proton nuclear magnetic resonance spectra (1H NMR) were recorded on a 600 MHz Varian® / Agilent® NMR spectrometer at 110 °C, using the solvent resonance as the internal standard (1H NMR: C2D2Cl4at 6.00 ppm).

[0108] Fourier-transform infrared (FTIR) spectra were obtained using a Bruker Vertex 80v FTIR spectrometer with an attenuated total reflectance (ATR) attachment. All the polymers were directly placed on the ATR crystal for measurements.

[0109] High temperature gel permeation chromatography (HT-GPC) spectra for HDPE and HDPE-BA samples were acquired using a Tosoh® EcoSEC® HLC-8321 GPC RI Detector. Columns consisted of one TSKgel® Hhr (30) HT2 Guard Column (7.5 mm ID x 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 20 7.5 cm, 30 μm), two TSKgel® GMHhr-H (20) HT2 columns (7.8 mm ID x 30 cm, 20 μm), and one TSKgel® Hhr HT-RC reference column (7.8 mm ID x 30 cm, 13 μm). HPLC grade 1,2,4-tricholorobenzene (0.1 wt.% BHT added as stabilizer) was used as the eluent at a flow rate of 1 mL min-1at 140 °C. Data was measured relative to polystyrene standards then transferred to HDPE and iPP according to corresponding α and K. GPC data for iPP and iPP- Py were obtained using a Malvern high temperature GPC instrument equipped with refractive index, viscometer, and light scattering detectors at 150°C with 1,2,4-trichlorobenzene (stabilized with 150 ppm BHT) as the mobile phase. A calibration curve was established using polystyrene standards in triple detection mode. All molecular weights reported are based on the triple detection method.

[0110] Thermalgravimetric analysis (TGA) was conducted using a NETZSCH® Simultaneous Thermal Analysis 449 F1 Jupiter® in the temperature range of 40–600 °C with polymers of 2-5 mg at a temperature ramp rate of 10 °C / min. The buoyancy effect was corrected by performing blank measurements for each sample using the temperature program and crucibles. Differential scanning calorimetry (DSC) was used to determine the thermal characteristics of the polyolefins and functionalized polyolefins using a NETZSCH® Differential Scanning Calorimeter 214 Polyma®. The DSC measurements were performed on 2–3 mg of polymer samples in the temperature range of -180–200 °C for HDPE-related samples and -80–200 °C for iPP-related samples at a temperature ramp rate of 10 °C / min. Data were taken from the second thermal scanning cycles. Synthesis of functionalized polyolefins

[0111] All reactions were performed under N2 using Schlenk-line techniques. To prepare HDPE-BA, HDPE (750 mg), 2-ClAQ (7.5 mg, 0.115 mol% relative to repeat units of HDPE), v-BA (398.5 mg, 10 mol%), and chlorobenzene (100 mL) were added to a 350-mL flask. The mixture was sonicated for 1 min and bubbled with N2 for 20 min. The rubber septum was then equipped with a pre-evacuated ballon. After HDPE was fully dissolved at 130 °C, the mixture was irradiated with a 395 nm LED (Howsuper®-UVLED, UVLED H6015-S) for 1 h with stirring. After the reaction, the hot mixture was poured into a beaker containing 600 mL of methanol or acetone. The precipitate was filtered using a Buchner funnel with a coarse frit and washed with methanol or acetone at least three times. The polymers were dried in a vacuum oven at 100 °C overnight and then used for characterization or further blending.

[0112] To prepare iPP-Py, iPP (1125 mg), 2-ClAQ (7.5 mg, 0.115 mol%), v-Py (585 µL, 20 mol%), and chlorobenzene (100 mL) were added to a 350-mL flask. The resulting 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 21 mixture was bubbled with N2 for 20 min. The rubber septum was then equipped with a pre- evacuated balloon. After iPP polymer pallets were fully dissolved at 150 °C, the reaction temperature was decreased to 130 °C, and the mixture was irradiated with a 365 nm LED (Howsuper-UVLED, UVLED H6015-S) for 16 h at this temperature. After the reaction, the hot mixture was poured into a beaker containing 600 mL of methanol or acetone. The precipitate was filtered using a Buchner funnel with a fine frit and washed with methanol or acetone for at least three times. The polymers were dried in a vacuum oven at 100 °C overnight and then used for characterization or further blending.

[0113] The synthesis of BA-Functionalized HDPE / iPP blend (f-PE:iPP-BA) followed a procedure similar to HDPE-BA, with the substitution of HDPE (750 mg) with a mixture of HDPE / iPP (585 / 251 mg). The polymers were fully dissolved at 150 °C, and the reaction was done at 130 °C. The purification step was identical to that of HDPE-BA.

[0114] The synthesis of Py-Functionalized HDPE / iPP blend (f-PE:iPP-Py) followed a procedure similar to iPP-Py, with the substitution of iPP (1125 mg) with a mixture of HDPE / iPP (585 / 251 mg). The purification step was the same as that of iPP-Py.

[0115] Note that the reaction time can be adjusted to achieve different degrees of functionality, determined by comparing the integration of H from BA or Py with that of H in the polyolefins in the1H NMR spectra.

[0116] Synthesis of TOADT: Tetraoctylammonium decatungstate (TOADT) was prepared as follows. Tetraoctylammonium bromide (TOAB) (4.0 g, 7.3 mmol) and Na2WO4⋅2H2O (6.7 g, 20.2 mmol) were dissolved in water (300 mL and 200 mL, separately). The solutions were acidified to pH 2 with concentrated hydrochloric acid solution and then heated to 90 °C. Upon mixing the solutions at 90 °C, viscous precipitation was observed immediately, indicating the formation of TOADT. The slurry was stirred for 10 minutes in a 90 °C water bath, after which the liquid was decanted, leaving the viscous solid adhering on the flask bottom. The solid phase was washed with DI water (3 × 30 mL) with sonication and then dried in a vacuum oven at 90 °C overnight. The TOADT product was obtained as a viscous, light-yellow solid.

[0117] To characterize the DT anions in TOADT, it was dissolved in acetonitrile at a concentration of 10-5M for the UV-vis measurement. The successful syntheses of DT catalysts were confirmed by the characteristic absorption peak at 323 nm in the UV-vis spectra recorded on Agilent Cary 60 UV / VIS Spectrometer. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 22 Synthesis of functionalized polyolefins with TOADT: The procedures were the same as those used for the synthesis of functionalized polyolefins with 2-ClAQ, except that 0.115 mol% of 2-ClAQ was replaced with 0.23 mol% of TOADT. Tensile testing experiments

[0118] Polyolefin blends (3 g) were tested for compatibilization with 5 wt% or 10 wt% of functional polyolefins being added, maintaining a stoichiometric ratio of acid and base at 1:1.

[0119] A polyolefin blend of HDPE:iPP (70:30) was treated with 10 wt% of acid-base compatibilizers (ABCs) each with a functional degree of 1.4% as follows. To a 500 mL flask containing a solution of chlorobenzene (35 mL) and DMF (7 mL), 120 mg of HDPE-BA was added. The resulting mixture was bubbling with N2for 20 min, heated to 130 °C and maintained at this temperature until all the polymers were dissolved. Then 180 mg of iPP-Py was added to the mixture under N2 and dissolved. The resulting clear solution was stirred for an hour. Afterwards, another portion of chlorobenzene (100 mL) was slowly added, followed by HDPE (1890 mg) and iPP (810 mg). The resulting solution was heated to 150 °C to fully dissolve iPP. The temperature was decreased to 130 °C and was maintained for 16 hours. The hot mixture was poured into a beaker containing 600 mL of methanol or acetone, precipitating the polymer blends, which were then filtered and washed with methanol or acetone three times to obtain a polyolefin blend, dried in vacuo oven at 100 °C overnight. Similarly, a blend of HDPE:iPP (70:30) with 5wt% of acid-base compatibilizers was prepared using 60 mg of HDPE-BA, 90 mg of iPP-Py, 1995 mg of HDPE, and 855 mg of iPP. In the case of virgin HDPE:iPP (70:30) blend, 2100 mg of HDPE and 900 mg of iPP were used, and chlorobenzene was used as the solvent.

[0120] The resulting blend was pressed using a Carver® Bench Top Standard Heated Press (model 4386, 12-ton capacity) with electrically heated platens. Polymer samples (2.5– 3 g) were sandwiched between thin, non-stick aluminum foil sheets in a stainless-steel mold (inset dimensions: 75 × 35 × 0.75 mm3) fabricated in-house and compressed between two 6″ × 6″ electrically heated platens with minimal pressure for 5 min at 190 °C, then pressed at 3000 psi for 10 min and at 20000 psi for 5 min. Finally, the pressed films were removed from the melt press and cooled to room temperature by submerging them into a water bath.

[0121] Tensile tests were performed on ASTM D-638 Standard Type-V tensile bar (dog- bones) specimens using an Instron® universal testing system (model 68TM-30) equipped with a 100 N load cell and operated at room temperature. Sample thickness (approximately 0.75 mm) was measured using calipers. The specimens were tightly placed between textured 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 23 grips with a grip separation of 25 mm and pulled at a constant strain rate of 10 mm / min until breakage. Measurements were repeated for at least 3 specimens, and average values are reported. Transmission electron microscopy (TEM) imaging

[0122] Films of polymer blends were trimmed into small pieces (ca.1 mm × 1 mm) and immobilized with household epoxy onto aluminum poles. Cryo-microtome sectioning was conducted using a Leica® EM UC7 ultramicrotome equipped with a Leica® EM FC7 cryo- ultramicrotomy chamber and a DIATOME® cryo 35° diamond knife (TED PELLA INC., Redding, CA) at –120 °C. Sample slices (1 mm / s and 50–70 nm) were obtained and transferred onto Cu grids (carbon type B 200 mesh, TED PELLA, INC.). TEM samples were stained with vapor by placing them along with stabilized 0.5 wt% RuO4aqueous solution (STREM CHEMICALS INC., Newburyport, MA) in a Petri dish within a closed chamber for 30 min to enhance phase contrast. TEM images were captured by FEI Tecnai Osiris® 200kV TEM with the objective aperture set at 70%. For polymer blends with smaller domains, high- angle annular dark-field field scanning TEM (HAADF-STEM) mode was applied to obtain a higher resolution. Domain size statistics of TEM images

[0123] TEM images were analyzed in ImageJ®, followed by data analyses in Mathematica® to evaluate the domain size. Scanning electron microscopy (SEM) imaging

[0124] Polymer strips near the fracture point after tensile tests were trimmed and mounted to the SEM stage with the fracture surfaces exposed. The samples were coated with 6 nm of iridium using a Cressington 208 iridium sputtering tool. The coated samples were analyzed on a HITACH® SU-70 SEM (10 kV). Wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) measurements

[0125] X-ray scattering experiments were conducted with a Xenocs® Xeuss 3.0 small / wide X-ray scattering system. Each X-ray scattering pattern was captured with an acquisition time of 1 hour in vacuo (< 1 mbar) at room temperature.

[0126] Twenty seven modified polyolefin samples were prepared following the procedures described above. Their conditions and results are summarized in Table 1 below. These modified polyolefin samples were added to HDPE / iPP blends to successfully and surprisingly compatibilize them as discussed above. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 24 Table 1.v-BA: 4-vinylbenzoic acid; v-Py: 4-vinylpyridine; MA: maleic acid; FA: fumaric acid; MPA: methyl 3-(pyridin-4-yl)acrylate; CA: cinnamic acid; DMM: dimethyl maleate; v-BC: 4-vinylbenzyl chloride; and 2-ClAQ: 2-chloroanthraquinone. OTHER EMBODIMENTS All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 25 otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features. From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the claims. 4902-8691-3806, v.1

Claims

BC2024.013.wan BCOT-002-WO1 26 WHAT IS CLAIMED IS:

1. A compatibilized polyolefin blend comprising polyethylene, polypropylene, and a pair of acid-base compatibilizers (ABCs), wherein the ABCs have an acid compatibilizer and a base compatibilizer and the pair of ABCs is selected from the group consisting of: (i) the acid compatibilizer is an acid polyethylene containing polyethylene modified with a plurality of acid functional groups and the base compatibilizer is a base polypropylene containing polypropylene modified with a plurality of base functional groups; (ii) the acid compatibilizer is an acid polypropylene containing propylene modified with a plurality of acid functional groups and the base compatibilizer is a base polyethylene containing polyethylene modified with a plurality of base functional groups; and (iii) the acid compatibilizer is a first modified polyolefin and the base compatibilizer is a second modified polyolefin, in which the first modified polyolefin is a first polyolefin modified with a plurality of acid functional groups, the second modified polyolefin is a second polyolefin modified with a plurality of base functional groups, and each of the first and second polyolefins contains polyethylene and polypropylene.

2. The compatibilized polyolefin blend of claim 1, wherein the acid or base functional groups are selected from the group consisting of a carboxyl group, a sulfonic acid group, a phosphonic acid group, a hydroxyl group, a phenol group, a thiol group, a nitro group, a borane group, an anhydride group, a carbocation group, an amine group, a pyridine group, an imidazole group, a phosphine group, an amide group, a nitrile group, an imine group, an ether group, a sulfide group, and a carbonyl group; preferably, the acid functional groups are carboxyl groups and the base functional groups are pyridine groups; more preferably, the acid functional groups are derived from 4-vinylbenzoic acid and the base functional groups are derived from 4-vinylpyridine.

3. The compatibilized polyolefin blend of claim 1 or 2, wherein each of the acid and base compatibilizers has a degree of functionality of 0.1 to 10 mol%; the molar ratio of the acid functional groups and the base functional groups is 1:4 to 4:1, preferably 1:2 to 2:1, and more preferably 1:1.2 to 1.2:

1.

4. The compatibilized polyolefin blend of any one of claims 1-3, comprising 5-94 wt% of polyethylene, 94-5 wt% of the polypropylene, 0.5-5 wt% of the acid compatibilizer, 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 27 and 0.5-5 wt% of the base compatibilizer; wherein polyethylene is high-density polyethylene, very low-density polyethylene, linear low-density polyethylene, or any combination thereof, and polypropylene is isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, or any combination thereof.

5. A compatibilized polyolefin blend comprising polyethylene, polypropylene, a modified polyethylene, and a modified polypropylene, wherein the modified polyethylene is polyethylene modified with a first group, the modified polypropylene is a polypropylene modified with a second group, the first group is one of an acid group and a base group, the second group is the other of the acid group and the base group.

6. The compatibilized polyolefin blend of claim 5, wherein the first group is one of carboxyl and pyridinyl, the second group is the other of carboxy and pyridinyl, the molar ratio of the first group and the second group is 1:4 to 4:1, preferably 1:2 to 2:1, and more preferably 1:1.2 to 1.2:1; and the compatibilized polyolefin blend contains 5-94 wt% of polyethylene, 94-5 wt% of the polypropylene, 0.5-5 wt% of the modified polyethylene, and 0.5-5 wt% of the modified polypropylene.

7. A method of compatibilizing polyolefins comprising the steps of: (i) providing a first modified polyolefin containing an acid functional group, in which the first modified polyolefin is prepared by irradiating a first mixture containing a first polyolefin, a first photocatalyst, and a first modifier to obtain the first modified polyolefin, and the first modifier contains a C=C double bond and the acid functional group; (ii) providing a second modified polyolefin containing a base functional group, in which the second modified polyolefin is prepared by irradiating a second mixture containing a second polyolefin, a second photocatalyst, and a second modifier to obtain the second modified polyolefin, and the second modifier contains a C=C double bond and the base functional group; and (iii) mixing the first polyolefin, the first modified polyolefin, the second polyolefin, and the second modified polyolefin to obtain a compatibilized polyolefin blend.

8. The method of claim 7, wherein each of the first and second polyolefins, independently, is polyethylene, polypropylene, or a combination thereof; polyethylene is 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 28 high-density polyethylene, low-density polyethylene, linear low-density polyethylene, or any combination thereof; and polypropylene is isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, or any combination thereof; preferably polyethylene is high-density polyethylene having 200-5000 repeat units of ethylene (-CH2-CH2-), and polypropylene is an isotactic polypropylene having 100-5000 repeat units of propylene (-CH(CH3)-CH2-).

9. The method of claim 7 or 8, wherein the compatibilized polyolefin blend contains 5-94 wt% of the first polyolefin, 0.5-5 wt% of the first modified polyolefin, 94-5 wt% of the second polyolefin, and 0.5-5 wt% of the second modified polyolefin; and the weight ratio of the first modified polyolefin and the second modified polyolefin is 1 : 10 to 10 : 1 10. The method of any one of claims 7-9, wherein each of the first and second photocatalysts, independently, is an anthraquinone or a decatungstate salt; preferably, the first and second photocatalysts, independently, is 2-chloroanthraquinone, anthraquinone, anthraquinone-2-sulfonate, anthraquinone-2-carboxylic acid, 1-chloro-anthraquinone, 1,5- dichloroanthraquinone, 1,8-dichloroanthraquinone, 1-hydroxyanthra-quinone, 1,2- dihydroxyanthraquinone, 1,8-dihydroxyanthraquinone, 1-aminoanthraquinone, 1,5- diaminoanthraquinone, sodium decatungstate (NaDT), tetraoctylammonium decatungstate (TOADT), tetrabutylammonium decatungstate (TBADT), or tetraphenylphosphonium decatungstate (TPPDT); and more preferably, each of the first and second photocatalysts is 2- chloroanthraquinone.

11. The method of any one of claims 7-10, wherein the acid or base functional group is a carboxyl group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, a phenol group, a thiol group, a nitro group, a borane group, an anhydride group, a carbocation group, an amine group, a pyridine group, an imidazole group, a phosphine group, an amide group, a nitrile group, an imine group, an ether group, a sulfide group, or a carbonyl group; preferably, the first modifier is 4-vinylbenzoic acid, 2-vinylbenzoic acid, 3-vinylbenzoic acid, 1,2-bis(4-carboxyphenyl)ethene, styrene-4-sulfonic acid, maleic acid, fumaric acid, maleic anhydride, dimethyl maleate, dibutyl maleate, diallyl maleate, 2-butenoic acid, cinnamic acid, 3-(pyridin-4-yl)acrylic acid, vinyl sulfonic acid, vinyl phosphonic acid, diethylstilbestrol, benfotiamine, GDC-0810, mucochloric acid, tetra(p-hydroxyphenyl)ethylene, 4-(1,2,2- 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 29 triphenylvinyl)phenol, dihydroxyfumaric acid, mucobromic acid, endoxifen, 2,3,3- trichloroacrylic acid, clomiphene, 2-cyano-3-methylbut-2-enoic acid, or isopropylidenemalonic acid, and the second modifier is 4-vinylpyridine, 2-vinylpyridine, 3- vinylpyridine, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(2-pyridyl)ethene, 1,2-bis(3-pyridyl)ethene, 4-styrylpyride, 4-[2-(4-nitrophenyl)ethenyl]-pyridine, methyl 3-(pyridin-4-yl)acrylate, 4- vinyl-piperidine, 3-vinyl-piperidine, 2-vinyl-piperidine, t-butyl N-vinylcarbamate, 1- vinylimidazole, 2-vinylimidazole, 4-vinylaniline, 3-vinylaniline, 2-vinylaniline, tamoxifen, teriflunomide, ospemifene, diaminomaleonitrile, 2,3-diaminomaleonitrile, [bis(methylthio)methylene]malononitrile, (1-ethoxyethylidene)malono-nitrile, ethyl 2-cyano- 3,3-di(methylsulfanyl)acrylate, octocrylene, ethenetetracarbonitrile, (E)-ethyl 2-cyano-3- ethoxybut-2-enoate, isopropylidenemalononitrile, etocrylene, 1,1,3-tricyano-2-amino-1- propene, benfotiamine, GDC-0810, endoxifen, clomiphene, 1-chloro-1-(dimethylamino)-2- methyl-1-propene, diethyl isopropylidenemalonate, di-isopropyl azodicarboxylate, acrylonitrile, 1,2-dicyanoethylene, methyl vinyl ketone, 4-penten-3-one, 4-vinylbenzyl chloride, 3-vinylbenzyl chloride, 2-vinylbenzyl chloride, or 1,1,2,2-tetrachloroethylene; and more preferably, the first modifier is 4-vinylbenzoic acid and the second modifier is 4- vinylpyridine.

12. The method of any one of claims 7-11, wherein each of the first and second photocatalysts is present at a level of 0.001 mol% to 3 mol% relative to the repeat units of first or second polyolefin, preferably at 0.01 mol% to 1 mol%, and more preferably at 0.1 mol% to 0.3 mol%; and the first modifier is present at a level of 1 mol% to 100 mol% relative to the repeat units of the first polyolefin, preferably at 5 mol% to 50 mol%, and more preferably at 10 mol% to 30 mol%; and the second modifier is present at a level of 1 mol% to 100 mol% relative to the repeat units of the second polyolefin, preferably at 5 mol% to 50 mol%, and more preferably at 10 mol% to 30 mol%.

13. The method of any one of claims 7-12, wherein the irradiating step on either the first or second polyolefin is performed (i) without a solvent or in a solvent selected from the group consisting of chlorobenzene, benzonitrile, naphthalene, diphenyl ether, and bromobenzene; (ii) at a temperature of 100 ºC to 250 ºC, preferably at 105 ºC to 150 ºC, and more preferably 110 ºC to 130 ºC; or (iii) using a light having a wavelength of 200 nm to 420 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 30 nm, preferably 250 nm to 410 nm, and more preferably 300 nm to 395 nm; or (iv) for 10 minutes to 50 hours.

14. The method of any one of claims 7-13, wherein the first or second modified polyolefin has a degree of functionality of 0.1 to 10 mol% relative to the repeat units of the first or second polyolefin.

15. A method of functionalizing a polyolefin comprising the step of irradiating a mixture containing a polyolefin, a photocatalyst, and a modifier to obtain a modified polyolefin, wherein the polyolefin is polyethylene, polypropylene, or a combination thereof; and the modifier contains (i) a C=C double bond and (ii) an acid or base functional group.

16. The method of claim 15, wherein the modifier is 4-vinylbenzoic acid, 2-vinyl- benzoic acid, 3-vinylbenzoic acid, 1,2-bis(4-carboxyphenyl)ethene, styrene-4-sulfonic acid, maleic acid, fumaric acid, maleic anhydride, dimethyl maleate, dibutyl maleate, diallyl maleate, 2-butenoic acid, cinnamic acid, 3-(pyridin-4-yl)acrylic acid, vinyl sulfonic acid, vinyl phosphonic acid, diethylstilbestrol, benfotiamine, GDC-0810, mucochloric acid, tetra(p-hydroxyphenyl)ethylene, 4-(1,2,2-triphenylvinyl)phenol, dihydroxyfumaric acid, mucobromic acid, endoxifen, 2,3,3-trichloroacrylic acid, clomiphene, 2-cyano-3-methylbut- 2-enoic acid, isopropylidenemalonic acid, 4-vinylpyridine, 2-vinylpyridine, 3-vinylpyridine, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(2-pyridyl)ethene, 1,2-bis(3-pyridyl)ethene, 4-styrylpyride, 4-[2-(4-nitrophenyl)ethenyl]-pyridine, methyl 3-(pyridin-4-yl)acrylate, 4-vinyl-piperidine, 3- vinyl-piperidine, 2-vinyl-piperidine, t-butyl N-vinylcarbamate, 1-vinylimidazole, 2-vinyl- imidazole, 4-vinylaniline, 3-vinylaniline, 2-vinylaniline, tamoxifen, teriflunomide, ospemifene, diaminomaleonitrile, 2,3-diaminomaleonitrile, [bis(methylthio)methylene]- malononitrile, (1-ethoxyethylidene)malononitrile, ethyl 2-cyano-3,3-di(methylsulfanyl)- acrylate, octocrylene, ethenetetracarbonitrile, (E)-ethyl 2-cyano-3-ethoxybut-2-enoate, isopropylidenemalononitrile, etocrylene, 1,1,3-tricyano-2-amino-1-propene, benfotiamine, clomiphene, 1-chloro-1-(dimethylamino)-2-methyl-1-propene, diethyl isopropylidene- malonate, di-isopropyl azodicarboxylate, acrylonitrile, 1,2-dicyanoethylene, methyl vinyl ketone, 4-penten-3-one, 4-vinylbenzyl chloride, 3-vinylbenzyl chloride, 2-vinylbenzyl chloride, or 1,1,2,2-tetrachloroethylene. 4902-8691-3806, v.1BC2024.013.wan BCOT-002-WO1 31 17. The method of claim 15 or 16, wherein the polyolefin is high-density polyethylene, very low-density polyethylene, linear low-density polyethylene, an isotactic polypropylene, a syndiotactic polypropylene, an atactic polypropylene, or any combination thereof. 4902-8691-3806, v.1

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