Synthesis of succinylated poly(4‐hydroxystyrene) and its application for negative‐tone photoresist

Atom transfer radical polymerization (ATRP) was used to prepare poly(acetoxystyrene) (PAS) with a controlled molecular weight and narrow polydispersity. Using 1‐phenylethylbromide (PEBr)/CuBr/Cu(0)/2,2′‐bipyridine as an initiating system, the heterogeneous ATRP of 4‐acetoxystyrene was carried out to form PAS as a precursor polymer. The reaction follows the first‐order kinetics with respect to the conversion of monomer. A linear molecular weight (polydispersities Mw/Mn = 1.07–1.27) indicates the “living”/controlled nature of polymerization. The obtained PAS was chemically modified to obtain succinylated poly(hydroxystyrene) (Succ‐PHS). The formulation of Succ‐PHS, crosslinker (benzoguanamine‐formaldehyde), and triphenylsulfonium triflate (TPST) as a photo acid generator (PAG) was carried out by UV irradiation using an i‐line tool. The performance of the resultant polymer as the negative resist pattern photoresist for photolithography was studied with instrumental techniques. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3560–3566, 2007     

Synthesis and characterization of poly[(methyl methacrylate)‐co‐(methacrylic acid)] for a UV‐sensitive aqueous base developable lithographic plate

Syntheses of the copolymers of methyl methacrylate and methacrylic acid were carried out by free radical chain polymerization in the presence of benzoyl peroxide (BPO) as an initiator. The effects of the monomer ratio and polymerization time on the averaged molecular weights, polydispersity index, and glass transition temperature were investigated. FTIR and NMR were used for functional group characterization, GPC for average molecular weights and the distribution, elemental analysis for CHO content, and DSC for the glass transition temperature. The copolymers were mixed with tripropylene glycol diacrylate (TPGDA) and trimethylol propane ethoxylated triacrylate (TMPEOTA), 2‐hydroxy‐2‐methyl‐1‐phenyl‐propan‐1‐one (Darocur® 1173) and benzophenone (Darocur® BP) with anthraquinone for visibility of images. The photosensitive coating was spin‐coated onto the anodized aluminum plate on which a thin film was formed. The wet film was then coated with PVA solution as an oxygen barrier layer. The plate assembled with a control wedge and a black color separation film was exposed to UV radiation at different exposure times. The plate was developed in a dilute alkaline developer. The resulting plate was evaluated for its reproduction properties in terms of surface properties (hydrophilic/hydrophobicity) by contact angle measurement of image/nonimage areas, resolution by microline, tone reproduction, and adhesion tests. The article describes the results of the syntheses, characterizations, and uses of the copolymer as a binder of a negative, lithographic printing plate. The present lithographic printing plate is good for a medium viscosity printing ink to produce medium printing quality on uncoated paper. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1829–1837, 2002     

Synthesis and characterization of poly(acrylate amic acid) and its application as negative‐tone photosensitive polyimides

The dianhydride monomer 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride and two diamine monomers, 4,4′‐diamino‐3,3′‐biphenyldiol (HAB) and 2,4‐diaminophenol dihydrochloride (DAP), were used to synthesize a series of poly(hydroxyl amic acid). Further functionalization by grafting acrylate groups yields the corresponding poly(acrylate amic acid) that underwent a crosslinking reaction on exposure to UV‐light and was used as a negative‐tone photosensitive polyimide (PSPI). The analysis of chemical composition and molecular weight of these poly(amic acid)s determined by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography revealed that the molecular weight of the poly(hydroxyl amic acid) increased with the molar content of HAB in the feedstock, because HAB exhibited higher polymerization reactivity than DAP. Moreover, the degree of grafting acrylate groups onto poly(hydroxyl amic acid) was determined by ¹H‐NMR spectroscopy. The photoresist was formulated by adding 2‐benzyl‐2‐N,N‐dimethylamino‐1‐(4‐morpholinophenyl) butanone (IRG369) and isopropylthioxanthone as a photoinitiator, tetra(ethylene glycol) diacrylate as a crosslinker, and tribromomethyl phenyl sulfone as a photosensitizer. The PSPI precursor exhibited a photosensitivity of 200 mJ/cm² and a contrast of 1.78. A pattern with a resolution of 10 μm was observed in an optical micrograph after thermal imidization at 300°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of a branched photosensitive copolymer and its application for negative‐type photoresists

Novel branched copolymers, poly(styrene‐alt‐maleic anhydride) (BPSMA), were synthesized through mercapto chain‐transfer polymerization with styrene, maleic anhydride (MA), and 4‐vinyl benzyl thiol (VBT). Then, the hydroxyl of hydroxyethyl methacrylate was reacted with MA to synthesize branched photosensitive copolymers, p‐BPSMAs. Fourier transform IR spectroscopy and ¹H‐NMR indicated that the synthesis was successful. Gel permeation chromatography indicated that the molecular weight decreased with increasing content of VBT. The thermal properties were characterized by thermogravimetric analysis; the results show that the thermal decomposition temperature of the BPSMAs was greatly enhanced. Real‐time IR was used to evaluate the UV‐curable kinetics of the p‐BPSMAs; the results show that the p‐BPSMAs could rapidly photopolymerize under UV irradiation in the presence of photoinitiators. Moreover, the photoresist based on the p‐BPSMAs exhibited improved photosensitivity when the VBT content increased, and the photoresist with 12 mol % VBT content had a low value of the dose that retained 50% of the original film thickness (10 mJ/cm²), and a 50‐μm resolution could be achieved compared to a linear photoresist. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42838.     

Synthesis of polysiloxane‐grafted fluoropolymers and their hydrophobic properties

A polydimethylsiloxane with an epoxide end group was grafted onto a fluoropolymer that had hydroxyl side chains by using protonic or Lewis acids as catalysts. Strong acids such as trifluoromethanesulfonic acid were found to be effective for the grafting of the polydimethylsiloxane of relatively large molecular weight (M_n 4440). A coating prepared from the graft polymer was so hydrophobic that a water droplet of 10 μL slid down on its inclined plane surface (30° with respect to the horizontal). ESCA analysis revealed that the siloxane branches are preferentially present on the surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1955–1963, 2000     

Fabrication of Robust Hydrophobic and Super‐Hydrophobic Polymer Films with Onefold or Dual Inverse Opal Structures

Hydrophobic and super‐hydrophobic materials have many important applications, but most of the artificially hydrophobic and super‐hydrophobic surfaces suffer from poor durability. Herein, a facile method is reported to fabricate robust hydrophobic and super‐hydrophobic polymer films through backfilling the silica colloidal crystal templates with the mixture of fluoropolymer, thermoset hydroxyl acrylate resins, and curing agent. After removal of the template, 3D ordered porous structures are obtained. The obtained polymer films have not only excellent hydrophobic or super‐hydrophobic properties but also good stability against temperatures, acids, and alkalis. Dual ordered porous structure can obviously enhance the hydrophobicity of polymer films compared to unitary one.

     

An autonomous self‐healing hydrogel based on surfactant‐free hydrophobic association

Self‐healing hydrogels are attractive for a variety of applications including wound dressings and coatings. This paper describes the facile preparation and characterization of an autonomous self‐healing hydrogel system comprising surfactant‐free hydrophobic associations. The hydrogel comprised a copolymer of benzyl methacrylate (B), octadecyl methacrylate (O), and methacrylic acid (MA). The hydrogels were prepared via a controlled dehydration procedure to achieve the formation of strong intermolecular hydrophobic associations of the octadecyl groups above a critical polymer concentration. Fractured hydrogels healed within 30 min without any external intervention. Increasing hydrogel polymer content from 31 wt % to 39 wt % resulted in a threefold increase in the shear modulus and 50% reduction of the relaxation time. Addition of 4 mM NaCl to a hydrogel of 31 wt % polymer content resulted in 2.5 times longer relaxation time and 24% decrease in shear modulus. The hydrogels swelled up water by up to four times its weight, which corroborates the robustness of the hydrophobic association crosslinks. The bulk properties of the hydrogels are discussed in terms of the hydrophobic associations of the O‐groups and the electrostatic interaction of the MA‐groups in the polymer chains. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44800.     

Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO₂) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO₂ was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO₂ and modified SiO₂ were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO₂ and modified SiO₂ on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO₂ and modified SiO₂ was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO₂‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature (T_g) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry     

Dual pH‐ and thermal‐responsive nanocomposite hydrogels for controllable delivery of hydrophobic drug baicalein

Hydrogels have been widely used as mild biomaterials due to their bio‐affinity, high drug loading capability and controllable release profiles. However, hydrogel‐based carriers are greatly limited for the delivery of hydrophobic payloads due to the lack of hydrophobic binding sites. Herein, nano‐liposome micelles were embedded in semi‐interpenetrating poly[(N‐isopropylacrylamide)‐co‐chitosan] (PNIPAAm‐co‐CS) and poly[(N‐isopropylacrylamide)‐co‐(sodium alginate)] (PNIPAAm‐co‐SA) hydrogels which were responsive to both temperature and pH, thereby establishing tunable nanocomposite hydrogel delivery systems. Nano‐micelles formed via the self‐assembly of phospholipid could serve as the link between hydrophobic drug and hydrophilic hydrogel due to their special amphiphilic structure. The results of transmission and scanning electron microscopies and infrared spectroscopy showed that the porous hydrogels were successfully fabricated and the liposomes encapsulated with baicalein could be well contained in the network. In addition, the experimental results of response release in vitro revealed that the smart hydrogels showed different degree of sensitiveness under different pH and temperature stimuli. The results of the study demonstrate that combining PNIPAAm‐co‐SA and PNIPAAm‐co‐CS hydrogels with liposomes encapsulated with hydrophobic drugs is a feasible method for hydrophobic drug delivery and have potential application prospects in the medical field. © 2018 Society of Chemical Industry     

Fatty acid methyl ester heterogeneous self‐metathesis in hydrophobic green solvent: Mass transfer limitations,catalyst recyclability,and stability

The role of room‐temperature ionic liquids (RTILs), [bmim][PF₆] and [bmim][Tf₂N], as reaction media regarding the catalytic activity and stability of methyltrioxorhenium (MTO) supported on ZnCl₂‐modified mesoporous Al₂O₃ has been studied for self‐metathesis of a functionalized olefin, methyl oleate. The humidity influence on the catalytic activity was probed. The catalyst recycling ability and the kinetics of the metathesis reaction using these RTILs were also investigated. It was found that the MTO‐based catalyst was efficient in viscous hydrophobic RTIL solvents. However, their high viscosity was found to increase the mass transfer limitations thus somewhat impacting the reaction kinetics. Nevertheless, better catalyst stability was reached allowing its possible recycling when used in RTIL media.     

Optimized statically non‐wetting hydrophobic electrospun surface of perfluorocyclobutyl aryl ether polymer

A statically non‐wetting highly hydrophobic fibrous surface was generated from biphenyl perfluorocyclobutyl aryl ether polymer (BP‐PFCB) by electrospinning. The optimization of solution parameters, which include concentration of the solution and number‐average molecular weight of the polymer, was followed by optimization of the instrumental parameters, which include flow rate, inter‐electrode voltage and inter‐electrode distance. Varying these parameters resulted in different degrees of hydrophobicity on the generated surfaces. The degree of hydrophobicity was determined by measuring static water contact angles. The effects of these variations in electrospinning parameters on the thickness of the fibers constituting the surface were also observed. It was found that the hydrophobic nature of the electrospun fibrous surface of BP‐PFCB depended on two factors: fluorine concentration and thickness of the fibers. During the optimization of the parameters, three different morphological regimes, namely beads, beaded fibers and fibers, were observed. The fine tuning of electrospinning parameters eventually produced a statically non‐wetting, highly hydrophobic surface which predominantly consisted of an intricate network of nanoscale fibers. © 2013 Society of Chemical Industry     

Towards new environmentally friendly fluoroelastomers: from facile chemical degradation to efficient photo‐crosslinkable reaction

Our objective is to develop a versatile and facile method that allows the synthesis of novel primary fluorinated co‐oligomers as precursors of photo‐crosslinkable networks. Transparent carboxyl‐terminated fluorinated co‐oligomers with molecular weights ranging between 2000 and 10 400 g mol^?1 were synthesized via facile degradation. The structural changes of fluorinated backbone were investigated using various analysis techniques. Then two major approaches, namely esterification and ring opening, were applied to obtain photochemical diacrylates (HEMA‐ and GMA‐IEM‐terminated co‐oligomers). These two precursors can be cured in 60 s under UV radiation without high temperature, high pressure or toxic solvent. The glass transition temperatures of HEMA‐ and GMA‐IEM‐terminated fluoropolymers at about ?20 °C, assessed from differential scanning calorimetry, showed an increase after crosslinking, and the glass transitions at 20 °C were no longer observed. These two crosslinked films were found to have higher decomposition temperatures, when compared to starting precursors. The contact angles on the surface of the two elastomer materials were only about 74° and 78°, which increased to 105° and 110° after UV irradiation. The tensile strength of the two cured fluoroelastomers can still reach 1.3 MPa at 200 °C. © 2019 Society of Chemical Industry     

Dial‐a‐size: Precision quantum dot nanopatterning using cheap,off‐the‐shelf copolymers

In the use of block copolymers as templates for nanolithography, deposition, or etching, substantial time and cost savings can be achieved through the use of algebraic models for block copolymer feature size as a function of both the polymer's molecular weight and the relative concentration of a homopolymer additive. Desired average pore diameters and spacing can be achieved on the first try, using off‐the‐shelf polymers in a wide range of molecular weights. This allows precise nanoscopic components such as quantum dots to be patterned over large areas rapidly, repeatably, and at very low cost. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dually stimuli‐responsive hyperbranched polyethylenimine with LCST transition based on hydrophilic–hydrophobic balance

Dually stimuli‐responsive hyperbranched polyethylenimine derivatives (HPEI‐star‐PPOs) were successfully synthesized through Michael addition of commercial HPEI, poly(propylene oxide) dimethacrylate, and 2‐mercaptoethanol. In aqueous solution, these HPEI‐star‐PPOs exhibited response to temperature and pH. The corresponding lower critical solution temperature (LCST) could be readily adjusted by changing the feed ratio of HPEI to PPO, which also presents the ratio of hydrophilicity to hydrophobicity, indicating that this LCST transition is based on hydrophilic–hydrophobic balance. Because of the tertiary amine as well as unreacted primary or secondary amine that can be protonated during pH decreases, HPEI‐star‐PPOs exhibited a pH‐dependent thermoresponse. The 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay against COS‐7 cells demonstrated that HPEI‐star‐PPO had relatively low cytotoxicity compared to HPEI. All these characteristic suggest that this stimuli‐responsive polymer is a promising functional material for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A Dual‐Crosslinked Strategy to Construct Physical Hydrogels with High Strength,Toughness, Good Mechanical Recoverability,and Shape‐Memory Ability

A novel type of physical hydrogel based on dual‐crosslinked strategy is successfully synthesized by micellar copolymerization of stearyl methacrylate, acrylamide, and acrylic acid, and subsequent introduction of Fe³⁺. Strong hydrophobic associations among poly(stearyl methacrylate) blocks form the first crosslinking point and ionic coordination bonds between carboxyl groups and Fe³⁺ serve as the second crosslinking point. The mechanical properties of the hydrogel can be tuned in a wide range by controlling the densities of two crosslinks. The optimal hydrogel shows excellent mechanical properties (tensile strength of ≈6.8 MPa, elastic modulus of ≈8.0 MPa, elongation of ≈1000%, toughness of 53 MJ m^?3) and good self‐recovery property. Furthermore, owing to stimuli responsiveness of physical interaction, this hydrogel also shows a triple shape memory effect. The combination of two different physical interactions in a single network provides a general strategy for designing of high‐strength hydrogels with functionalities.     

Effect of hydrophobic comonomer content on assembling of poly (N‐isopropylacrylamide) and thermal properties

Copolymers of N‐isopropylacrylamide and octadecyl acrylate (PNO), of which the content of octadecyl acrylate (ODA) was 1.3% (PNO 1.5), 1.7% (PNO 2.0), and 3.0% (PNO 4.0), were prepared using a free radical reaction. Various assemblies were obtained depending on the concentration of PNOs and the contents of ODA. Hydrophobic interaction between ODA residues is likely to act as crosslinker. PNO 1.5 formed hydrogel at the concentration of 7%. With PNO 2.0, hydrogels were formed when the concentration was 5 and 7%. With PNO 4.0, the opaque gel was obtained when the concentration was 7%. Upon heating across the lower critical solution temperature, the hydrogels shrank but the opaque gel was broken down into a suspension. At 40°C, the release degrees of fluorescein isothiocyanate‐dextran were much smaller than those of release at 23°C. The temperature‐sensitive release is due to temperature‐sensitive swelling ratio. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Positive‐tone,aqueous‐developable,polynorbornene dielectric: Lithographic,and dissolution properties

A positive‐tone, aqueous base soluble, polynorbornene (PNB) dielectric formulation has been developed. The photolithographic solubility switching mechanism is based on diazonaphthoquinone (DNQ) inhibition of PNB resin functionalized with pendent fluoroalcohol and carboxylic acid substituents. The optical contrast (at 365 nm) was found to be 2.3. The maximum height‐to‐width aspect ratio of developed line and space features was 3 : 2. The sensitivity, D₁₀₀, of a formulation containing 20 pphr of DNQ photoactive compound (PAC) was calculated to be 408 mJ cm^?2. The effects of the PAC molecule structure on miscibility and dissolution of the photosensitive films in aqueous base developer were studied. The effect of the monomer composition of the PNB polymer on the dissolution rate of the formulated PNB resin was evaluated. A unique dissolution and swelling behavior was observed. The effect is attributed to a copolymer synthesized with two monomers each of which is susceptible to deprotonation in aqueous base. FTIR measurements showed that the pure PNBFA has a small percentage of free hydroxyl groups, which did not change appreciably by the addition of PAC to the mixture. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Interaction between the strong anionic character of strong anions and the hydrophobic association property of hydrophobic blocks in macromolecular chains of a water‐soluble copolymer

The copolymerization of acrylamide, sodium 2‐acrylamido‐2‐methyl propane sulfonate, and styrene was carried out in a microemulsion medium, and ternary copolymers based on polyacrylamide, which contained both strong anionic groups (? SO₃Na) and hydrophobic blocks (polystyrene), were synthesized. The structures and compositions of the copolymer were characterized by various means (Fourier transform infrared, ultraviolet, and elemental analysis). The aqueous solution properties were investigated with a florescence probe technique and apparent viscosity measurements, and the interactions between the strong anionic character of the anionic groups and the hydrophobic association behavior of the hydrophobic blocks was intensively examined. After the simultaneous addition of the strong anionic groups and hydrophobic association blocks to the main chains of polyacrylamide, the synergism of the electroviscosity effect of the strong anionic groups and the hydrophobic association effect of the hydrophobic blocks obviously enhanced the apparent viscosity of aqueous copolymer solutions, and the synergism of greater salt tolerance of the strong anionic groups and the strengthened hydrophobic association of the hydrophobic blocks in brine solutions resulted in increased salt resistance for the copolymer. However, the presence of strong anionic groups (? SO) in the macromolecules weakened the intermolecular hydrophobic association effect of the copolymer in aqueous solutions to a certain degree; that is, the strong anionic groups produced a certain negative influence on the hydrophobic association effect of the hydrophobic blocks. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 714–722, 2005     

Cashew nut shell liquid based t‐BOC protected alternating “high ortho” copolymer as a possible e‐beam resist: Characterization using multi‐dimensional NMR spectroscopy

A cardanol/m‐cresol‐based copolymer was esterified using di‐tert‐butyl dicarbonate (t‐BOC), which makes it a suitable candidate as a possible e‐beam resists. This work reports a full characterization of the product using the techniques of FTIR and UV–Visible spectroscopy, one dimensional ¹H NMR, ¹³C NMR, DEPT‐135. Two dimensional NMR experiments such as, COSY, HSQC, and HMBC have been employed for exhaustive probing of the microstructural details of this derivatized copolymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and network parameters of hydrophobic poly(N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐lauryl acrylate) hydrogels

Hydrophobic poly(N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐lauryl acrylate) [P(DMAPMA‐co‐LA)] hydrogels with different LA content were synthesized by free‐radical crosslinking copolymerization of corresponding monomers in water by using N,N‐methylenebis(acrylamide) as the crosslinker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylethylenediamine as the activator. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in pure water. An interesting feature of the swelling behavior of the P(DMAPMA‐co‐LA) hydrogels with low LA content was the reshrinking phase transition where the hydrogels swell once and collapse as temperature was varied in the range of 30–40°C. The average molecular mass between crosslinks (M?_c) and polymer–solvent interaction parameter (χ) of the hydrogels were calculated from equilibrium swelling values. The enthalpy (ΔH) and entropy (ΔS) changes appearing in the χ parameter for the hydrogels were determined by using the Flory–Rehner theory based on the phantom network model of swelling equilibrium. The positive values for ΔH and ΔS indicated that the hydrogels had a positive temperature‐sensitive property in water, that is, swelling at a higher temperature and shrinking at a lower temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4159–4166, 2006