Polymers epoxy

Useful properties of epoxy resins include good adhesion, high chemical resistance and flexibility. However, when used in ED resists, they appear to be more difficult to remove than acrylic coatings. Epoxy resins used for 

ED resists are usually manufactured from a phenol, such as bisphenol A, by reaction with epichlorohydrin. 

Ciba-Geigy have described the use of epoxy resins in organic ED coatings that replace tin-lead solder as etch-resists [16]. A typical resin, which is formulated into a cataphoretic resist, is shown in Fig. 2.8. 

Both negative and positive working photoresists have been formulated with epoxy resins [11, 17]. The example in Fig. 2.9(a) is mixed with a polyamine resin to give a cataphoretic, negative-working resist [17], while that in Fig. 2.9(b) is reacted with a DNQ-sulphonyl chloride to give an anaphoretic, positive-working resist [11]. 

The prepolymer contains a 1,2 epoxy linkage which is made by a base-catalysed step-growth reaction between a diol, e.g. bisphenol A, and a 1,2 epoxide, e.g. epichlorhydrin. 

The curing (cross-linking) of the prepolymer can be achieved by either reaction with primary amines (often aromatic) which attack the epoxy end groups, or carboxylic acid anhydrides (e.g. phthalic anhydride) which react with the pendant hydroxy-groups. 

Added strength can be obtained by fibre reinforcement (especially carbon fibres) or improved toughness by adding terminally carboxylated buta-diene/acrylonitrile rubbers which react with the hydroxy groups. 

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Epichlorohydrin is a product of covulcanization of epichlorohydrin (epoxy) polymers with rubbers, especially di-polybutadiene. 

Fig. 24. Representative cross-linking systems employed in negative tone CA resists, (a) Epoxy polymers requiring organic solvent development, (b) PHOST-based cross-linking systems requiring aqueous development, (c) Monomeric cross-linking agents used in PHOST matrix polymers.

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

Hybrid systems of acrylics with other technologies have been reported. Aciylic and epoxy polymers can be coupled through the use of 2-methacryloloxyethyl phosphate. The phosphoric acid functionality reacts with epoxy and the methacrylate group copolymerizes with the acrylic backbone [ 145] (Scheme 14). 

The desire to replace cadmium is generally attributed to its toxicity, both in terms of process pollution and product corrosion, and several alternatives are feasible thicker zinc, tin-zinc alloy or tin-nickel alloy depending upon the precise application " . The demise of decorative nickel-chrome systems in the automotive industries of the world is partly due to cost and partly to market image, and not to technical performance where major improvements took place in the period 1960-1975 through the establishment of duplex nickel under-layers and micro discontinuous chromium top-layers. In the 1980s the trend has been towards black finishes produced generally by powder-applied epoxy polymers. 

Kinloch, A. J. Mechanics and Mechanics of Fracture of Thermosetting Epoxy Polymers. Vol. 72, pp. 45-68. 

Of course, the network strands cannot be stretched completely. Stretching ratios of 1.4 for PC [31, 90] and of 1.3 for epoxy polymers [37] have been reported. The chain contour length of the strands is an appropriate measure for a simple estimation of the number of strands that are stretched across the deformation zone. The chain contour length of the strands is assumed to be proportional to... 

The presence of redox catalysts in the electrode coatings is not essential in the c s cited alx)ve because the entrapped redox species are of sufficient quantity to provide redox conductivity. However, the presence of an additional redox catalyst may be useful to support redox conductivity or when specific chemical redox catalysis is used. An excellent example of the latter is an analytical electrode for the low level detection of alkylating agents using a vitamin 8,2 epoxy polymer on basal plane pyrolytic graphite The preconcentration step involves irreversible oxidative addition of R-X to the Co complex (see Scheme 8, Sect. 4.4). The detection by reductive voltammetry, in a two electron step, releases R that can be protonated in the medium. Simultaneously the original Co complex is restored and the electrode can be re-used. Reproducible relations between preconcentration times as well as R-X concentrations in the test solutions and voltammetric peak currents were established. The detection limit for methyl iodide is in the submicromolar range. 

First-generation polymer composites (e.g., fiberglass) used thermosetting epoxy polymers reinforced with randomly oriented short glass fibers. The filled epoxy resin could be cured into a permanent shape in a mold to give lightweight, moderately strong shapes. 

Bauman, A.D., High-value engineering materials from scrap rubber. Rubber World, 212, 30, 1995. Bagheri, R., Wilbams, M.A., and Pearson, R.A., Use of surface modified recycled rubber particles for toughening of epoxy polymers, Polym. Eng. Sci., 37, 245, 1997. 

FIG. 10 Compressive (a) yield strength and (b) moduli for the pristine epoxy polymer and the exfoliated epoxy-clay nanocomposites prepared from three different kinds of organomontmorillonites. (From Ref. 40.)... 

The residue produced from the 350°C run contained discernible resinite particles. In contrast, examination of the fluorescence of residues from the two 370° runs in blue light showed that little resinite was left undissolved other than that incorporated within a matrix of other macerals. Instead, a diffuse fluorescence had been imparted to the epoxy resin embedding medium. Presumably, the epoxy was able to dissolve some of the liquefied resin remaining after extraction with ethyl acetate. In the residue from the run at 400°C, only one discrete resinite particle was observed among the many coal particles embedded in the epoxy polymer. It appears that in a short time at 350°, most, but not all, of the resinite undergoes liquefaction. All other material in the sample needs considerably more severe treatment. 

Although the main use of impact modifiers is with thermoplastics, thermosets also benefit. The agent is added at the monomer stage. Thus epoxy polymers can be made less brittle by the addition of rubbers. Care has to be taken that the high temperature properties of the thermoset are not compromised. 

L. Olivier, N. Q. Ho, J. C. Grandidier, and M. C. Lafarie-Frenot, Characterization by Ultra-Micro Indentation of an Oxidized Epoxy Polymer, Pol. Degrad. Stab., 93,... 

Vitamin B12 derivatives are also effective catalysts for the electroreductive cyclization of bromoalkenes in conductive microemulsions,299 300 or for ring-expansion reactions in cyclic a-(bromomethyl)-(3-keto esters in DMF.301 Vitamin Bi2 attached to an epoxy-polymer has been used in electrosynthesis of valeronitrile by reductive coupling of iodoethane and acrylonitrile.302... 

The epoxy polymers are basically poly ethers. One type of epoxy polymer (or epoxy resins) are prepared from epichlorohydrin and bisphenol-A. The reaction is carried out with excess of epichlorohydrin. The various reactions for the preparation of an epoxy polymer are given in the following discussion. 

Epoxy resins find a large number of uses because of their remarkable chemical resistance and good adhesion. Epoxy resins are excellent structural adhesives. When properly cured, epoxy resins can yield very tough materials. They are used in industrial floorings, foams, potting materials for electrical insulations, etc. One of the principal constituents in many of the Fibre-reinforced plastics (FRP) is an epoxy polymer. 

Loss of Tin. The preparation and characterization of organ-otin-epoxy polymers have been reported earlier (3). In an effort to determine the loss of tin from these controlled release formulations, 0.5-mm thick coatings were kept immersed in 4% sodium chloride solution under conditions approximating Figure 2a. The concentration of TBTC1 in the aqueous phase was maintained low by continuously extracting it into hexane. Analysis of the coating at the end of 16 months revealed that not more than 2% tin was lost in any of the four cases studied. 

The measured G(x) value of representative epoxy polymers is approximately 10, but this value depends strongly on the structure of the polymer, its glass transition temperature and other characteristics. Since the crosslinking reaction that characterizes the COP resist functionality is a chain reaction, in theory, a single, electron-initiated event could result in the insolublization of an entire film of the resist material. Fortunately, because of the existence of chain terminating reactions, this does not occur and high resolution imaging of the resist material can be accomplished. 

Boll, D.J., Jensen, R.M., Cordner, L. and Bascom, W.D. (1990). Compression behaviour of single carbon filaments embedded in an epoxy polymer. J. Composite Mater. 24, 208-219. 

Netravali, A.N., Hcnstenburg, R.B., Phoenix, S.L. and Schwartz, P. (1989a). Interfacial shear strength studies using the single filament composite test, part I Experiments on graphite fibers in epoxy. Polym. Composites 10, 226-241. 

Hoh, K.P., Ishida, H. and Koenig, J.L. (1988). Spectroscopic studies of the gradient in the silane coupling agent/malrix interface in fiber glass-reinforced epoxy. Polym. Composites 9, 151-157. 

Bascom, W.D., Cottington, R.L., Jones, R.L. Peyser, P. (1975). The fracture of epoxy and elastomer modified epoxy polymers in bulk and as adhesives. J. Appl. Polym. Sci. 19 2545-2562. 

BMI polymers have glass transition temperatures in excess of 260°C and continuous-use temperatures of 200-230°C. BMI polymers lend themselves to processing by the same techniques used for epoxy polymers. They are finding applications in high-performance structural composites and adhesives (e.g., for aircraft, aerospace, and defense applications) used at tem-peratrues beyond the 150-180°C range for the epoxies. Bisnadimide (BNI) polymers are similar materials based on bisnadimides instead of bismaleimides. 

Vezenov D, Zhuk A, Whitesides G, Lieber C. Chemical force spectroscopy in heterogeneous systems intermolecular interactions involving epoxy polymer, mixed monolayers, and polar solvents. J Am Chem Soc 2002 124 10578-10588. 

It is evident that relaxation studies in the solid state can look at the motions which are responsible for the mechanical properties of the cured epoxy systems 43). Therefore, Garroway, Moniz and Resing continued to do relaxation studies 61). Garroway, et al. looked at four epoxy polymers based on the DGEBA resin. Two of the epoxy resins were cured with amines and the other two were cured with anhydrides. Proton enhanced spectra of the epoxy systems were generated. The solid state spectra were compared to the solution spectra of the unreacted epoxy. The< epoxy resin of interest was again DGEBA which was reacted with ... 

Fig. 12. C- 13 spectrum of the piperidine (PIP) cured DGEBA epoxy polymer at room temperature. The assignments have been discussed and the structure indicates a possible polymerization mechanism 2 ...

Garroway et al. 67) used solid state C-13 NMR studies on epoxy polymers to... 

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