Electrostatic Dissipating Properties of Poly(oxyethylene)amine

Synthesis, characterization and electrostatic dissipating ability of poly(oxyethylene) block polyesteramides. J. J. Lin , Y. C. Sheen , F. P. Tseng , ...
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Ind. Eng. Chem. Res. 1998, 37, 4284-4289

Electrostatic Dissipating Properties of Poly(oxyethylene)amine-Modified Polyamides Mang-Yao Young and Jiang-Jen Lin* Department of Chemical Engineering, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China

A series of hydrophilic poly(ether amide)s were prepared from the copolymerization of dicarboxylic acids (including terephthalic, adipic, and sebacic acids) and two combined poly(oxyalkylene)diamines and characterized by GPC, NMR, IR, and DSC. The electrostatic dissipating property, probed by measuring the surface resistivity, was correlated with the molecular weight (MW), the weight content of the incorporated hydrophilic poly(oxyethylene)diamine, and the morphology of the resulting polymers. A wide range of surface resistivity from 1012 to 106.3 Ω/0 can be achieved. Poly(oxyethylene)diamine of MW 2000 is the most effective hydrophilic amine among those studied. The surface resistivity decreased from 109.9 to 108.7 to 107.8 to 107.6 Ω/0 with increasing incorporation of the hydrophilic poly(oxyethylene)diamine from 0 to 25 to 50 to 76 wt % accordingly, in the case of poly(sebacamide)s. Adding a second amine, either triethylene glycol diamine (MW 148) or poly(oxypropylene)diamine (MW 230), to the requisite poly(oxyethylene)diamine (MW 2000) rendered the polyamides to have good structural integrity. The importance of hydrogen bonding associated with amide functionality is indirectly evidenced by comparing the analogous polyamides with the polyamines, the latter prepared from the amine curing with the diglycidyl ether of bisphenol A. Introduction The amphipathic polymers derived from poly(oxyethylene glycol)s or PEG have versatile properties such as hygroscopicity, crystallinity, and metal-binding ability (Harris, 1992; Mutter et al., 1987). Their industrial applications widely cover the areas of polymeric surfactants (Yang and Rathman, 1996), dispersants, emulsifiers, thickeners, polymer blend compatibilizers, water absorbents, etc. (Piirma, 1992; Interrante, 1995). One of the specific applications for PEG-derived compounds is their complexation with alkali-metal salts to render materials having high electronic conductivity. For example, lithium-doped poly(ethylene oxide) materials with conductivities between 10-4 and 10-3 S cm-1 have potential applications for solid polymer electrolytes (MacCallum and Vincent, 1989; Scrosati, 1993; Linford, 1987). Without adding lithium, the poly(oxyethylene) functionalized polymers are hydrophilic in property and can absorb moisture on the surface. As a result, such polymeric materials could have an electrostatic charge dissipating ability, which is required for use in housing or packaging of magnetic, electrical, and military equipment. Conventionally, the low MW’s of hydrophilic ionic and nonionic surfactants such as quaternary ammonium salts were added to the plastics by physical blending or surface treatment to reduce the surface resistivity. The incorporation of poly(oxyethylene)-containing polyamide segments into poly(-caprolactam) could have a permanent effect on enhancing the polymer hydrophilicity, dye-absorbing, and static charge dissipating abilities (Okazaki et al., 1971; Fukumoto et al., 1992; Lee, 1993). In view of these industrial applications, we are interested in polymeric materials that have both good structural integrity and electrostatic dissipating ability * Corresponding author. Telephone: +886-4-285-2591. Fax: +886-4-285-4734. E-mail: [email protected].

through an appropriate surface conductivity. Polyamides consisting of poly(oxyethylene) functionality seem to fit these requirements. A very high content of hydrophilic poly(oxyethylene) segments in polyesters (Yang and Rathman, 1996) and polyamides (Speranza and Henkee, 1994) is characteristic of water-soluble polymers. Here we report the synthesis of waterinsoluble poly(ether amide) from the reactions of various diacids and two combined poly(oxyalkylene)diamines. These tailored structures of poly(ether amide)s are composed of a high molecular weight of poly(oxyethylene)diamine and a low molecular weight of diamines. The existence of poly(oxyethylene) segments in polyamides will enhance the hydrophilicity of the polymers, and the low MW the diamines are for polymer structural modification. The factors affecting the electrostatic dissipating property of these polymeric materials are investigated, and a mechanism involving hydrogen bonding to rationalize the observed surface resistivity is suggested. Experimental Section Preparation of Poly(oxyethylene)-Segmented Poly(ether amide). Procedure A. Various copolyamides containing hydrophilic poly(oxyethylene)amide segments were prepared by two different proceduress tandem and random syntheses. A typical tandem synthesis of poly(sebacamide) from diacids, 2000 MW hydrophilic diamines, and low MW diamines is described in the following example. To a 250-mL, threenecked, round-bottomed resin flask, equipped with a heating devise, temperature controller, mechanical stirrer, nitrogen inlet-outlet line, Dean-Stark trap, and air condenser, were charged sebacic acid (13.0 g, 64.5 mmol) and poly(oxyethylene)diamine of 2000 average molecular weight (structure I in Scheme 1, i.e., Jeffamine ED-2003, purchased from Huntsman Chemical Co.,

10.1021/ie980197s CCC: $15.00 © 1998 American Chemical Society Published on Web 10/09/1998

Ind. Eng. Chem. Res., Vol. 37, No. 11, 1998 4285 Scheme 1. Representative Structures for the Reaction of Dicarboxylic Acid and Poly(oxyalkylene)diamines

white waxy solid, mp 37-40 °C, total amine 0.95 mequiv/g; 25.0 g, 12.5 mmol). With stirring, the mixture was heated to 150 °C for 3 h and followed by adding the second poly(oxypropylene)diamine of molecular weight 230 (structure III, i.e., Jeffamine D-230, purchased from Huntsman Chemical Co., amorphous liquid having a total amine content of 8.45 mequiv/g; 12.0 g, 52.0 mmol). The reaction was further held at 220 °C for an additional 4 h. During the process, water was generated and removed under nitrogen flow through a Dean-Stark trap. At 220 °C, the product mixture was a viscous light-colored liquid which was poured into a flat stainless steel container and allowed to cool in air to room temperature. The sample was conditioned for 24 h at room temperature under an atmosphere of 50% relative humidity and measured to have a surface resistivity of 106.6 Ω/0 from a ST-3 Model (Simco Co.) tester according to ASTM Method D257-93. Surface resistivity is expressed in ohms/square (Ω/0), in which the size of the square is immaterial. The average molecular weight was estimated to be 12 500 with a polydispersity of 1.6 by using gel permeation chromatography (Waters GPC 150 CV) with a calibration from standard polystyrenes. The FT-IR spectrum showed the characteristic absorptions at 1645 and 1546 cm-1 (carbonyl of amides) and 1100 cm-1 (C-O-C ethers). The relative intensity of the 1100-cm-1 absorption is correlated to the presence of poly(oxyethylene) segments in polymers at various weight percentages. Carbon-13 nuclear magnetic resonance (NMR) spectrophotometry was performed with a Varian Gemini 300 spectrometer using CDCl3 as the solvent and showed a peak at 171 ppm for the carbonyls. The glass transition temperature (Tg) and the melting point (Tm) were measured by a Seiko SII model SCC/5200 differential scanning calorimeter at a heating rate of 5 °C/min. This particular polyamide starting from Jeffamine ED-2003 at 50 wt % in reactants at an acid/amine molar ratio of 1.0 was calculated to have a hydrophilic poly(oxyethylene) segment of ca. 52 wt %. Various copolyamides were prepared from diacid and two diamines, Jeffamine ED-2003 at 0, 35, 50, or 75 wt %, and a second diamine (II or III). In each case, the total equivalent of two amines is equal to the acids; in others words, the acid/amine molar ratio is 1:1. The

diacids included terephthalic, adipic, and sebacic acids. During the polymerization, the generated water was removed. Procedure B. With similar experimental conditions to procedure A, the mixtures of two different poly(oxyalkylene)diamines were added simultaneously to the diacid at room temperature. The mixtures of sebacic acid (52.1 g, 0.26 mol), Jeffamine ED-2003 (100.0 g, 0.05 mol), and Jeffamine 230 (47.9 g, 0.21 mol) in the reaction flask were slowly heated to 160 °C for 3 h and 220 °C for 4 h. During the process, the generated water was removed through a Dean-Stark trap under nitrogen flow. After the reaction, the product was poured into a flat container and conditioned under 50% relative humidity. The polyamides prepared from the random process showed identical IR and NMR spectroscopy to the analogous products of procedure A. The surface resistivity for this particular product was 106.6 Ω/0. Preparation of Poly(oxyethylene)-Segmented Polyamines. The following is a representative example of the preparation of a series of polyamines from the reaction of mixed poly(oxyalkylene)diamines and the diglycidyl ether of bisphenol A. The mixture of poly(oxyethylene)diamine of MW 2000 (i.e., Jeffamine ED2003; 10.0 g, 5.0 mmol), poly(oxypropylene)diamine of MW 230 (i.e., Jeffamine D-230; 1.48 g, 6.3 mmol), and the diglycidyl ether of bisphenol A (8.5 g, 22.5 mmol) was thoroughly stirred at elevated temperature and then poured into a mold container and cured at 60 °C for 2 h and 120 °C for 4 h. The cured polyamine contained ca. 50 wt % of block poly(oxyethylene) segments in the structure. The compound showed a Tg of -6 °C and a Tm of 49.2 °C. The surface resistivity was measured to be 109.2 Ω/0 after being conditioned in 50% humidity. Other polyamines containing hydrophilic Jeffamine ED-2003 amines at 25, 35, and 73 wt % were also prepared. Results and Discussion Synthesis of Poly(oxyethylene)-Containing Polyamides. The poly(oxyethylene)-segmented hydrophilic polyamides were prepared by the reaction of diacids (including terephthalic acid, adipic acid, and sebacic acid) and various poly(oxyalkylene)diamines at a 1:1 molar ratio of acid/amine according to Scheme 1. The

4286 Ind. Eng. Chem. Res., Vol. 37, No. 11, 1998 Table 1. Relationship of the Surface Resistivity and Calculated Weight Composition of Poly(oxyalkylene)amide Segments in Polyamides poly(oxyalkylene)amide,a wt % polyamideb

I

II

terephthamide

0 40 56 82 0 41 55 80 0 37 58 82 0 38 53 78 0 40 56 82 0 37 52 78

40 30 22 7

adipamide

sebacamide

III

54 39 27 9 40 41 22 7 54 41 30 13 40 30 22 7 54 34 25 9

surface solubility resistivity, in 10x Ω/0 waterc 11.0 7.4 8.1 8.4 12 7.1 7.8 8.8 10.7 7.8 7.7 6.3 9.2 7.7 6.9 6.3 9.5 8.8 8.4 7.7 9.9 8.7 7.8 7.6

N N N N N N N N S S S S N P S S P P P P P P P P

a I, poly(oxyethylene)diamine (average MW ) 2000). II, triethylene glycol diamine, H2N(CH2CH2O)2CH2CH2NH2. III, poly(oxypropylene)diamine, H2N(CH(CH3)CH2O)xCH2CH(CH3)NH2 (average MW ) 230). b Molar ratios of acid/(I + II) or (I + III) at 1.0. c Solubility test (1.0 g in 10 g of water): N, not soluble; S, soluble; P, partially soluble.

Figure 3. Poly(oxyethylene)amide (wt %) in sebacamide.

Figure 4. Hydrophilicity of the poly(oxyethylene) vs poly(oxypropylene) segments. Table 2. Surface Resistivity (10x Ω/0) of Poly(ether amide)s Prepared from Diacid,a Poly(oxyethylene)diamine (I),b and a Second Diamine (II or III)c surface resistivity, 10x Ω/0 DMT I,d wt %

II

adipic III

II

sebacic III

II

III

0 11 12 10.7 9.2 9.5 9.9 35 7.4 7.1 7.8 7.7 8.8 8.7 50 8.1 7.8 7.7 6.9 8.4 7.8 76 8.4 8.8 6.3 6.3 7.7 7.6 a DMT, dimethyl terephthalate. Adipic, adipic acid. Sebacic, sebacic acid. b I, poly(oxyethylene)diamine (average MW ) 2000). c II, triethylene glycol diamine, H N(CH CH O) CH CH NH . III, 2 2 2 2 2 2 2 poly(oxypropylene)diamine, H2N(CH(CH3)CH2O)xCH2CH(CH3)NH2 d (average MW ) 230). Based on the initial reactant composition.

Figure 1. Poly(oxyethylene)amide (wt %) in terephthamide.

Figure 2. Poly(oxyethylene)amide (wt %) in adipamide.

hydrophilic diamine I, consisting of an average middle poly(oxyethylene) block of 39.5 ethylene oxide units and a capped poly(oxypropylene) block of ca. 2.5 units at both ends, is a poly(oxyethylene)-rich, semicrystalline, and

water-soluble poly(ether amine). This hydrophilic poly(oxyethyleneoxypropylene)diamine and other poly(oxyalkylene)diamines, II with a molecular weight of 148 and III with an average molecular weight of 230, can be commercially produced by reductive amination of the corresponding polyol precursors (Moss, 1964; Yeakey, 1972). The poly(oxyethylene) block in structure I renders the hydrophilicity through moisture absorption. When this crystalline, solid diamine (mp 37.3 °C) alone was allowed to react with diacids including terephthalic, adipic, and sebacic acids at a 1:1 molar ratio of acid/ amine, the resulting polyamides were liquid or sticky semisolid at ambient temperature. To improve the polymers structural integrity, a second amine comonomer (II or III) is required. Triethylene glycol diamine (II) is an ethylene oxide-based and water-soluble amine which has a molecular weight of 148. Poly(oxypropylene)diamine (III) of MW 230 is a propylene oxide-based and less hydrophilic diamine. With the addition of low MW II or III along with the hydrophilic MW 2000 diamine I, the copoly(sebacamide)s, as an example, have good structural integrity and melting points ranging from 28 to 35 °C. It is noted that the polyamides generally have lower melting points than that of starting amine I (37.3 °C). Their molecular weights, determined by gel permeation chromatography using polystyrene standards, are typically around 12 500 with a

Ind. Eng. Chem. Res., Vol. 37, No. 11, 1998 4287 Scheme 2. Representative Polyamine Structures from Poly(oxyethylene)diamine Curing with the Diglycidyl Ether of Bisphenol A

Table 3. Surface Resistivities and Melting Points of Poly(oxyethylene)diamine and Diols Jeffamine Ω/0 mp,a °C ∆Hm,a J/g 10x

PEG

ED-2003

D-6000

1000

2000

8000

10.0 37.3 29.4

9.8 54.2 142.0

10.0 39.8 159.0

9.9 53.6 174.0

10.9 61.8 89.0

a Melting points (mp) and heat of melting (∆H ) were measured m by DSC.

Figure 5. Proposed dissipating electrostatic mechanism via hydrogen-bonding moisture absorption and ionization.

polydispersity of 1.6 for these polyamides derived from sebacic acid/poly(oxyethylene)diamine of MW 2000 (50 wt %)/poly(oxypropylene)diamine of MW 230 (27 wt %). Polyamides derived from terephthalic acid and a similar amine composition gave unexpected low molecular weight of 3900 and 2.7 (polydispersity). This perhaps is due to the lower reactivity of the acid. Copolyamides prepared from random and tandem procedures showed similar IR absorption but different surface resistivities. In general, the randomly prepared copolyamides had lower surface resistivities than those of the sequentially prepared copolyamides. There is no good explanation for this observation, but this implies the substantial effect of different polymer structural orientation. Table 1 shows the relationship of the surface resistivity and the calculated weight composition. Surface Resistivity of MW 2000 Poly(oxyethylene)diamide-Segmented Polyamides. The presence of poly(oxyethylene)diamide segments in polyamides gives rise to materials with hydrophilic properties due to their tendency to associate with moisture water molecules through hydrogen bonding. The hydrophilicity is reflected by the degree of electric conductivity of the polymer surface, measured as the surface resis-

tivity in units of ohms/square. Most plastics are electronic insulators which have surface resistivities higher than 1012 Ω/0 and will accumulate electrostatic charges. The materials with a surface resistivity lower than 1010 Ω/0 are considered as antistatics due to their ability to dissipate electrostatic charges. Our studies on the poly(oxyethylene)diamide-segmented polyamides indicated that their surface resistivities decreased with the increasing amounts of hydrophilic amines added, as shown in Table 1. For example, in the case of poly(sebacamide)s with the increasing addition of 0, 35, 50, and 76 wt % of the starting monomer I, the corresponding weight compositions of the poly(oxyethylene) segments in the polymers are calculated to be 0, 40, 56, and 82 wt %. Accordingly, the surface resistivities of these polyamides dropped from 109.5 to 108.8 to 108.4 to 107.7 Ω/0 when using II as the second amine monomer. When using MW 230 III as the comonomer, the surface resistivities of poly(sebacamide)s had the decreasing trend from 109.9 to 108.7 to 107.8 to 107.6 Ω/0. Similar trends were observed for poly(adipamide)s with increasing addition of I. With II as the second comonomer, the resistivities were lowered from 1010.7 to 107.8 to 107.7 to 106.3 Ω/0, and with III the resistivities were lowered from 109.2 to 107.7 to 106.9 to 106.3 Ω/0 accordingly. These values are further expressed in Figures 1-3. It is noteworthy that poly(sebacamide)s made from poly(oxypropylene)diamine of MW 230 or poly(oxyethylene)diamine of MW 148 alone without the addition of the hydrophilic diamine were measured to be 109.9 Ω/0 and 109.5 Ω/0, respectively. The high surface resistivities, again observed in the cases of poly(terephthamide)s and poly(adipamide)s, are attributed to the presence of low weight percent poly(oxyalkylene) segments (approximately 40 wt %) and also the difference in the hydrophilicity between the poly(oxypropylene) and poly(oxyethylene) functionalities (Figure 4). For clarity, the data of the surface resistivity are further summarized in Table 2.

4288 Ind. Eng. Chem. Res., Vol. 37, No. 11, 1998

Mechanism and Factors Affecting Surface Resistivities. It was unexpected for us to observe the adverse influence of adding a poly(oxyethylene)diamide segment in the poly(terephthamide) series in terms of their changes in surface resistivity. What was observed was the trend of increasing resistivities from 107.4 to 108.1 to 108.4 Ω/0 with increasing amounts of hydrophilic diamine I added. The reverse trends were realized for both II and III as the low MW comonomers. It was also noticed that the poly(phthalamide)s generally have higher resistivitiess1011 Ω/0 with II as the sole amine monomer and 1012 Ω/0 for III alonesthan their corresponding poly(adipamide)s and poly(sebacamide)s. These observations are contradicted by the assumption that the higher the hydrophilicity of the polyamides, the lower the surface resistivity. The second factor affecting the polymer surface resistivity is realized. In the case of poly(terephthamide)s, the fluidity or the free volume of the polymers can be significantly reduced through π-π interactions between aromatic groups. Therefore, the increasing weight composition of the poly(oxyethylene) segments could enhance the polymers crystallinity and decrease the polymers hydrophilicity to moisture. In other words, the surface conductivity is a function of two factorssthe quantity of water absorption through the hydrophilicity and the mobility of these water molecules. As a result, the overall surface conductivity of the poly(terephthamide)s decreased with increasing additions of amine I. In comparison with poly(adipamide)s or poly(sebacamide)s, the rigidity of poly(terephthamide)s can be indirectly evidenced by their relative higher surface resistivities when using 40 wt % of II or III as the sole amine monomers. The factor of polymer mobility contributes to the relatively high surface resistivity (1010 Ω/0) and melting point (37.3 °C) of the starting poly(oxyethylene)diamines (I). As shown in Table 3, the commercially available poly(oxyethylene)diamine of MW 2000 (i.e., Jeffamine ED-2003) is a semicrystalline solid which is directly measured to have a surface resistivity of 1010.0 Ω/0. A 2-4 orders of magnitude difference in surface resistivity was observed for the derived polyamides, as shown in Tables 1 and 2. This is probably due to the high order of the molecular arrangement through the pure form of poly(oxyethylene) segments. Similarly, the high surface resistivities are observed for various molecular weights of poly(oxyethylene)diamines and poly(ethylene glycol)s (PEGs), regardless of their substantial difference in crystallinity as indicated by melting points and crystallinity energy. It seems that the crystalline poly(oxyethylene)amines and PEGs have a high tendency to aggregate and have a relatively low tendency to adsorb or to transfer intrinsic water molecules. Surface Resistivity and Hydrogen Bonding. The lowering of surface resistivity is believed to be the result of hydrogen bonding. The poly(oxyethylene) segments are capable of absorbing moisture through hydrogen bonds (Harris, 1992). The partial ionization of water molecules may generate protons in equilibrium which can be the medium for electron transferring, as indicated in Figure 5. To demonstrate the importance of hydrogen bonding on lowering the surface resistivity of the polymers, a series of polyamines containing poly(oxyethylene) of 2000 MW segments were prepared according to the procedures used in the epoxy curing process (May, 1988; Lin, 1996). The preparation of polyamines consisting of I and III is described in Scheme

Table 4. Surface Resistivities of Poly(ether amine)s Prepared from the Glycidyl Ether of Bisphenol A and Mixed Amines I and III I, wt %

III, wt %

surface resistivity, 10x Ω/0

73 50 35 25

0 7.3 12.0 15.0

8.9 9.2 9.5 10.4

a Diamines I, poly(oxyethylene)diamine (average MW ) 2000), and III, poly(oxypropylene)diamine or H2N(CH(CH3)CH2O)xCH2CH(CH3)NH2 (average MW ) 230).

Figure 6. Idealized structures of analogous poly(ether amide)s and poly(ether amine)s.

2. The glycidyl ethers of BPA-connected polyamines composed of 73, 50, 35, and 25 wt % of poly(oxyethylene) blocks are solid materials having surface resistivities of 108.9, 109.2, 109.5, and 1010.8 Ω/0 accordingly, as recorded in Table 4. The surface resistivities are generally higher than those of the polyamides containing the same weight composition of poly(oxyethylene) segments, as shown in Tables 2 and 3. By comparing theanalogous structures of thepolyamides and polyamines in Figure 6, the importance of hydrogen bonding between CONH and the water molecule is revealed. Furthermore, a mechanism involving water absorption through hydrogen bonding as shown in Figure 4 is suggested. Conclusion The incorporation of poly(oxyethylene)diamide segments of MW 2000 into polyamides rendered a series of amphipathic polymers with good electrostatic dissipating properties. The surface resistivities could drop from 1012 to 10 6.3 Ω/0, depending on the weight composition of the hydrophilic poly(oxyethylene)amide in the polymers. The addition of a second low MW diamine comonomer improved the structural integrity of the polyamides. Poly(terephthamide)s, poly(adipamide)s, and poly(sebacamide)s derived from MW 2000 poly(oxyethylene)diamine had good structural integrity and surface resistivities ranging from 10 8.8 to 106.3 Ω/0. The changes in surface resistivity are due to the hydrogen-bonding association with moisture, evidenced by the comparison between the analogous polyamides and polyamines. The mobility of the poly(oxyethylene) segments could be the second factor. A mechanism involving the moisture absorption through hydrogen bonding of poly(oxyethylene) and amide functionalities as well as the electron transferring mediated by the flexible polymer backbone is proposed.

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Acknowledgment The financial support from Industrial Technology Research Institute (ITRI) and the National Science Council (NSC) of Taiwan is gratefully acknowledged. Literature Cited Fukumoto, T.; Yano, K.; Iwamoto, M. Polymer-ester Amide and Permanently Antistatic Resin Composition. U.S. Patent 5,096,995, 1992. Harris, J. M., Ed. Poly(Ethylene Glycol) Chemistry: Biotechnical and Biomedical Applications; Plenum: New York, 1992. Interrante, L. V., Ed. Materials Chemistry, An Emerging Discipline; Publishers: 1995. Lee, B. Electrostatic Dissipating Compositions. U.S. Patent 5,237,009, 1993. Lin, J. J. Aromatic Polyoxyalkylene Amidoamines as Curatives for Epoxy ResinssDerivatives from tert-Butyl Isophthalic Acid. 1996, 3 (2), 97-104. Linford, R. G., Ed. Electrochemical Science and Technology of Polymers 1; Elsevier Applied Science: London, 1987. MacCallum, J. R., Vincent, C. A., Ed. Polymer Electrolyte Reviews 1 and 2; Elsevier Applied Science: London, 1987 and 1989. May, C. A. Epoxy Resins, Chemistry and Technology; Marcel Dekker: New York, 1988. Moss, P. H. Nickel-Copper-Chromia Catalyst and the Preparation Thereof. U.S. Patent 3,152,998, 1964.

Mutter, M.; Altmann, K. H.; Gehrhardt, H. Functionalized Polyethylene Glycols and Polypeptides in Organic Synthesis and Catalyst. React. Polym. 1987, 6, 99-107. Okazaki, K.; Nakagawa, A.; Sugii, K. Composite Filaments and Fibers. U.S. Patent 3,558,419, 1971. Piirma, I. Surfactant Science Series, 34, Polymeric Surfactant; Marcel Dekker: New York, 1992. Scrosati, B., Ed. Application of electroactive polymers; Chapman & Hall: London, 1993. Sharma, R., Ed. Surfactant adsorption and surface solubilization; ACS Symposium Series 615; American Chemical Society: Washington, DC, 1995. Speranza, G. P.; Henkee, C. S. Water soluble polyamides from polyalkylene glycol diamines and polycarboxylic acids. U.S. Patent 5,324,812, 1994. Yang, C.; Rathman, J. F. Adsorption-solution structure relationships of PET/POET polymeric surfactants in aqueous solutions. Polymer 1996, 37 (20), 4621. Yeakey, E. L. Process for preparing polyoxyalkylene polyamines. U.S. Patent 3,654,370, 1972.

Received for review March 30, 1998 Revised manuscript received August 4, 1998 Accepted August 13, 1998 IE980197S