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18 KiB
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"protocol": "The synthesis of hydrophilic polymers involves utilizing unsaturated monomers such as acrylates and methacrylates, which can be cross-linked by ultraviolet light (UV) radiation. The process may employ a Michael addition reaction, using acetoacetate donors with multifunctional acrylate receptor compounds to yield polyesters with reactive pendent acrylate groups. These pendent groups facilitate cross-linking in a subsequent curing reaction, eliminating the need for added photoinitiators. Upon exposure to UV radiation, an acyl radical is formed, which acts as an internal photoinitiator, leading to the polymerization of the system.Polymers are synthesized by polymerizing ethylenically or acetylenically unsaturated polymerizable monomers or oligomers that have alpha, beta-unsaturation. The polymers must have an average molecular weight of at least 1000 daltons. The polymer backbone is terminated with at least one free unsaturated group at either end. Additionally, one or more monomers or oligomers used to create the polymer backbone should contain groups that can react with other compounds to form pendent functional groups. These pendent functional groups may either end in free unsaturated functional groups or other types of functional groups.Functional polymers may be prepared by first functionalizing one or more monomers or oligomers followed by free radical polymerization of the functionalized monomers or oligomers. Monomers with free hydroxyl (-OH), carboxyl (-COOH), or ester (—COO—R) groups are reacted with compounds having hydroxyl, carboxyl, ester, aminyl (-NH2 or —NHR), or isocyanate (—NCO) groups to form pendent functional groups. The polymerization process can occur in suspension solution (60°C to 80°C) or emulsion (−20°C to 60°C) form, typically at near or at 1 atmosphere pressure. Initiators like peroxide (e.g., dibenzoyl peroxide) or azo initiators (e.g., 2,2'-azobis(2-methylpropane nitrile)) may be used. Alternative methods like anionic polymerization or post polymerization functionalization may also be applied, which entails separately preparing the polymer backbone and pendant functional groups and subsequently joining them together. A free isocyanate can be reacted with a hydroxyl, carboxyl, or aminyl group on the polymer backbone at temperatures below 80°C for 1 to 8 hours to form linkages such as R—NH—C(O)—P or R—NH—C(O)—NR'-G-P. The presence of inert solvents and catalysts can be employed to accelerate reactions, and stabilizers or polymerization inhibitors may be added to prevent premature cross-linking.To synthesize hydrophilic polymers with functional groups, use polymerizable groups such as isocyanates, alkenes, and carboxylic acid derivatives for components A' and B. Base cleavable groups and optional spacer groups should be included in component Z, where suitable spacer groups can be alkyleneoxy or aryleneoxy types. The composition of Z may follow the formula S_x4(BCG)_y4, with S being a spacer group and BCG being a base cleavable group. Preferred base cleavable groups include anhydrides, esters, and carbonates. Aim for multiple base cleavable groups in the polymer structure, preferably at least two, with an emphasis on using four or more for enhanced functionality.1. Use difunctional branch-point monomers with polymerizable end groups that include base cleavable functional groups, such as (meth)acrylate esters. 2. Choose suitable difunctional monomers including acrylic anhydride, methacrylic anhydride, or ester linkages with (meth)acrylate end groups. 3. Mix multiple difunctional branch-point monomers in the range of 0.1 to 100 wt% based on the total weight of monomers. 4. Ensure that polymers contain acid functionality capable of forming a salt upon contact with alkaline developers, aiming for an acid number up to 250, preferably between 50 to 250. 5. Incorporate ester links in the backbone and/or side chains, targeting 2 to 50 ester links, ideally between 20 to 40. 6. Utilize isocyanate compounds with at least one free isocyanate group to react with hydroxyl-containing compounds. 7. Conduct the reaction at a 1:1 mole ratio of hydroxyl group to isocyanate group. 8. If desired, use free-radical generating compounds capable of promoting polymerization upon exposure to actinic radiation. 9. Incorporate hydrophilic components that provide water solubility or dispersibility, preferably with light absorbance at or above 300nm.To synthesize hydrophilic polymers with functional groups, use the following steps: 1. Functionalize photoinitiators (e.g., benzophenones, acetophenones) with reactive groups such as hydroxyl, carboxyl, or amine by reacting them with isocyanate groups on a carrier component to create urethane, amide, or urea bonds. 2. Alternatively, react an isocyanate group from the photoinitiator with a hydroxyl, carboxyl, or amine group on the carrier. 3. Form ester bonds by reacting an acid group with an alcohol group. 4. Optionally, incorporate aromatic chromophores that have light sensitivity in the range of 320 to 450 nm, joining these via similar methods used for photoinitiators. 5. For polymer backbone functionalization, ensure an average molecular weight of at least 1000 daltons, typically between 10,000 to 500,000 daltons. 6. Maintain reactive groups such as hydroxyl and carboxyl on the polymer backbone for solubility in alkaline solutions. 7. Optionally functionalize the polymer with 1.0 to 100 mole percent of reactive sites, preferably between 2 and 20 mole percent. 8. The synthesized polymer is then processed into liquid photoresists by dissolving in an organic diluent or water, followed by cross-linking upon exposure to radiation.A homogeneous solution containing 62.0 grams of methacrylic acid and 265.0 grams of methyl methacrylate was prepared. 75% by weight of the homogeneous solution were transferred into a second flask. The homogeneous solution of the first flask was diluted to 26.0% by weight solids and the homogeneous solution of the second flask was diluted to 86.50% by weight solids by adding sufficient methyl ethyl ketone. The first flask was mixed and heated to reflux under atmospheric conditions. 2.0 grams of 2,2'-azobis (2-methylbutyronitrile) was added to the reaction mixture, mixed and held at reflux for about 30 minutes. 6.25 grams of 2,2'-azobis (2-methylbutyronitrile) was mixed with 38.0 grams of methyl ethyl ketone and fed into the first flask along with the contents of the second flask over 4 hours while maintaining reflux. An additional amount of 9.0 grams of methyl ethyl ketone was then added to the first flask and the mixture was refluxed for an additional hour.In a separate clean dry air sparged addition funnel, 193.0 grams of polypropoxylated hydroxypropylmethacrylate (hydroxyl number $^{-158}$) was weighed out. The polypropoxylated hydroxypropylmethacrylate was added to a flask containing 1,6-hexamethylene diisocyanate biuret over about 1 hour with mixing while maintaining a temperature of $35^{\\circ}\\mathrm{C}$. The addition funnel was rinsed with 118.0 grams of methyl ethyl ketone, which was added to the flask containing the biuret, and the temperature was increased to $60^{\\circ}\\mathrm{C}$. The reaction was maintained for 3 hours at $60^{\\circ}\\mathrm{C}$ and monitored for completion using known analytical methods. The functionalized polymer was prepared by weighing out 763.0 grams of the acrylic polymer (47% solids) and 55.0 grams of methyl ethyl ketone in a clean, dry air-sparged flask, mixing, and heating to $45^{\\circ}\\mathrm{C}$. The urethane/acrylate moiety was added to the acrylic polymer over about 1 hour. Then, 0.50 grams of Irganox 1076 and 28.0 grams of methyl ethyl ketone were added to the reaction mixture, which was held at $45^{\\circ}\\mathrm{C}$ for 3 hours with constant mixing. The polymer main chain was functionalized with 6 mole percent of the moiety. 4.55 grams of 2,2'-azobis (2-methylbutyronitrile) were dissolved in 48.0 grams of methyl ethyl ketone and mixed, then added to the first flask over a period of 90 minutes while maintaining reflux. An additional 8.5 grams of 2,2'-azobis (2-methylbutyronitrile) mixed with 48.0 grams of methyl ethyl ketone was fed into the reaction mixture over about 150 minutes while maintaining reflux, followed by 23.0 grams of methyl ethyl ketone. At the end of the reaction, 2,2'-azobis (2-methylbutyronitrile) was thermally killed off to below parts per million concentrations. 150.0 grams of 1,6-hexamethylene diisocyanate biuret (23.0% NCO) were added to a clean dry, nitrogen-sparged flask along with 0.06 grams of dibutylin dilaurate, 0.05 grams of Irganox 1076, and 160.0 grams of methyl ethyl ketone. The flask was sparged with dry air, stoppered, mixed, and heated at about $35^{\\circ}\\mathrm{C}$.To prepare the acrylic polymer backbone, 70.0 grams of 2-hydroxyethyl methacrylate was added to a mixture of methacrylic acid and methyl methacrylate. For the functionalized pendent groups, 1 mole of isophorone diisocyanate was reacted with about one mole of hydroxy methacrylate to form an isophorone diisocyanate hydroxy methacrylate moiety.The isocyanate groups of isophorone diisocyanate hydroxy methacrylate were reacted with the hydroxyl groups of 2-hydroxyethyl methacrylate to form a functionalized polymer with 6 mole percent functionalization.One mole of 1,6-hexamethylene diisocyanate trimer is added to a clean dry, nitrogen sparged flask. 0.06 grams of dibutylin dilaurate, 0.05 grams of Irganox (antioxidant) 15 and 160.0 grams of methyl ethyl ketone are also added to the flask. The flask is sparged with dry air and stoppered. The components are mixed and heated at 35°C. Two moles of a polyalkoxylated hydroxyalkyl (meth)acrylate, or two moles of hydroxyalkyl (meth)acrylate are added to the flask, mixed with the trimer, and heated at 35°C for one hour. The reaction temperature is increased to 60°C and the reaction is maintained for 3 hours.$60\\\\textrm{g}$ of a diacrylate acceptor compound and $0.5\\\\mathrm{~g~}$ of diazabicyclo-undecene (DBU) are weighed into a $500~\\\\mathrm{ml}~3$ -neck round bottom flask equipped with a mechanical stirrer and addition funnel. $15.0~\\\\mathrm{g}$ of an acetoacetate derived donor compound is weighed into the addition funnel. The acceptor compound and DBU are mixed for 5 minutes prior to the addition of the donor compound. The donor compound is then added dropwise to the stirred acceptor/DBU mixture over a 15 minute period. The solution is warmed to 54 degrees Celsius after the addition of the donor compound is complete. After the 1s exotherm subsided in 100 minutes, a viscous yellow liquid is obtained which does not gel upon standing.To 1.1 parts of the prepared imidazole dissolved in 100 parts of ethanol containing 12 parts of potassium hydroxide, add 450 parts of a 1% by weight water solution of potassium ferricyanide at a rate of 5 parts per minute for 1.5 hours with continuous stirring. After the reaction, isolate the oxidation product in an amount of 1.0 parts by filtration and wash with water until free from ferricyanide. Dry the product at 56°C for eight hours under 0.1 mm mercury pressure after predrying overnight in a vacuum oven at 50°C. Solvate the product with two moles of ethanol for every three moles of biimidazole. Dry a portion of the ethanol-solvated product azeotropically with cyclohexane or recrystallize from ether to produce non-solvated material. Furthermore, prepare an oligomer composed of methylmethacrylate and acrylic acid by free radical polymerization in an aqueous acidic environment at reflux between 90°C to 100°C for a water-soluble photoinitiator yield of 85% to 90% by weight.Prepare a homogeneous solution containing 197 grams of methacrylic acid, 512 grams of methyl methacrylate, and 79 grams of poly(ethoxylated) monomethacrylate. Transfer 75% by weight of the homogeneous solution into a second flask.1. Dilute the first flask to 25% by weight solids. Dilute the homogeneous solution of the second flask to 60% by weight solids by adding sufficient methyl ethyl ketone. 2. Mix the first flask and heat to reflux under atmospheric conditions. Add 2.0 grams of 2,2'-azobis (2-methylbutyronitrile) to the reaction mixture, mix, and hold at reflux for 30 minutes. 3. Mix 6.0 grams of 2,2'-azobis (2-methylbutyronitrile) with about 40 grams of methyl ethyl ketone. Feed this into the first flask along with the contents of the second flask over 4 hours while maintaining reflux. 4. Add an additional 9.0 grams of methyl ethyl ketone to the first flask and reflux for an additional hour. 5. Dissolve 5.0 grams of 2,2'-azobis (2-methylbutyronitrile) in 50.0 grams of methyl ethyl ketone. Add this mixture to the first flask over a period of 90 minutes while maintaining reflux. 6. Mix 9.0 grams of 2,2'-azobis (2-methylbutyronitrile) with 50.0 grams of methyl ethyl ketone and feed into the reaction mixture over 150 minutes while maintaining reflux. 7. Add an additional 25.0 grams of methyl ethyl ketone to the reaction mixture. 8. At the end of the reaction, thermally kill off 2,2'-azobis (2-methylbutyronitrile) to below parts per million concentrations. Set aside the acrylic copolymer main chain or backbone.5.31 grams of 1,6-hexamethylene diisocyanate biuret (23.% free-NCO) were added to a clean dry, nitrogen sparged flask. 0.06 grams of dibutylin dilaurate, 0.05 grams of Irganox 1076 (antioxidant) and 160.0 grams of methyl ethyl ketone were also added to the flask. The flask was sparged with dry air and stoppered. The components were mixed and heated at 35°C. In a separate clean dry air sparged addition funnel, 15.97 grams of poly(ethoxylate-b-caprolactone) monomethacrylate oligomer was weighed out. The oligomer was added to the flask containing the 1,6-hexamethylene diisocyanate biuret over 1 hour with mixing and maintaining a temperature of 35°C. The addition funnel was then rinsed with 118.0 grams of methyl ethyl ketone to remove any remaining oligomer. The rinse was added to the flask containing the biuret with a temperature increased to 60°C. The reaction was maintained for 3 hours at 60°C. The reaction was monitored to determine completion of the synthesis of a urethane acrylate moiety by high pressure liquid chromatography (HPLC). The functionalized polymer was prepared by weighing out 763.0 grams of the acrylic copolymer (47% solids) and 50.0 grams of methyl ethyl ketone to a clean, dry air sparged flask. The combination was mixed and heated to 45°C. The urethane/acrylate moiety was then added to the acrylic polymer over 1 hour. 0.50 grams of Irganox 1076 and 30.0 grams of methyl ethyl ketone was added to the reaction mixture. The reaction contents were held at 45°C for 3 hours with constant mixing. The resulting copolymer was composed of 25 mole % of methyacrylic acid, 65 mole % of methyl methacrylate and 10 mole % of poly(ethoxylated) monomethacrylate residues. The copolymer main chain was 6 mole % functionalized with the moiety.A homogeneous solution containing 77.5 grams of 2-hydroxyethyl methacrylate, 194 grams of methacrylic acid, and 504 grams of methyl methacrylate was prepared. 75% by weight of the homogeneous solution was transferred to a second flask. The homogeneous solution of the first flask was diluted to 25% by weight solids and the homogeneous solution of the second flask was diluted to 60% by weight solids by adding sufficient methyl ethyl ketone. The first flask was mixed and heated to reflux under atmospheric conditions. 2.0 grams of 2,2'-azobis (2-methylbutyronitrile) was added to the reaction mixture, mixed and held at reflux for 30 minutes. 6.25 grams of 2,2'-azobis (2-methylbutyronitrile) was mixed with 40.0 grams of methyl ethyl ketone and fed into the first flask along with the contents of the second flask over 4 hours while maintaining reflux. An additional amount of 9.0 grams of methyl ethyl ketone was then added to the first flask and the mixture was refluxed for an additional hour. 5.0 grams of 2,2'-azobis (2-methylbutyronitrile) were dissolved in 50.0 grams of methyl ethyl ketone and mixed. The mixture was then added to the first flask over a period of 90 minutes while maintaining reflux. 9.0 grams of 2,2'-azobis (2-methylbutyronitrile) were mixed with 50.0 grams of methyl ethyl ketone and then fed into the reaction mixture over 150 minutes while maintaining reflux. An additional amount of 23.0 grams of methyl ethyl ketone was added to the reaction mixture. At the end of the reaction, 2,2'-azobis (2-methylbutyronitrile) was thermally killed off to below parts per million concentrations. The acrylic polymer main chain or backbone product was set aside. 150.0 grams of 1,6-hexamethylene diisocyanate biuret (23.0% -NCO) were added to a clean dry, nitrogen sparged flask. 0.06 grams of dibutylin dilaurate, 0.05 grams of Irganox 1076 (antioxidant) and 160.0 grams of methyl ethyl ketone were also added to the flask. The flask was sparged with dry air and stoppered. The components were mixed and heated at 35°C. In a separate clean dry air sparged addition funnel, 190.0 grams of poly(ethoxylate-b-caprolactone) monomethacrylate oligomer was weighed out. The oligomer was added to the flask containing the 1,6-hexamethylene diisocyanate biuret over 1 hour with mixing and maintaining a temperature of 35°C. The addition funnel was then rinsed with 120.0 grams of methyl ethyl ketone to remove any remaining oligomer. The rinse was added to the flask containing the biuret with a temperature increased to 60°C. The reaction was maintained for 3 hours at 60°C. The reaction was monitored to determine completion of the synthesis of the urethane acrylate moiety. 750.0 grams of the acrylic copolymer and 55.0 grams of methyl ethyl ketone were weighed out in a clean, dry air sparged flask. The combination was mixed and heated to 45°C. The urethane/acrylate moiety was then added to the acrylic copolymer over 1 hour. 0.50 grams of Irganox 1076 and 30.0 grams of methyl ethyl ketone was added to the reaction mixture. The reaction contents were held at 45°C for 3 hours with constant mixing. The polymer main chain was 6 mole percent functionalized with the moiety.Select a photoinitiator from the following options: imidazole dimer, anthraquinone, naphthaquinone, ketal, triazine compound, or combinations thereof. Ensure the polymer has an average molecular weight of at least 1000 daltons. For enhanced properties, incorporate multiple ester links, specifically greater than 2. Consider including one or more side chains with greater than 2 ester links. Optionally, use hexaarylbiimidazole as the imidazole dimer and include additional components such as a stripping agent, plasticizer, surfactant, aromatic chromophore, dye, or combinations thereof to modify the polymer."
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