NONIONIC ‘SURFACTANTS
`
`EDITED BY
`
`MARTIN J. SCHICK
`LEVER BR(‘I'1"m'KS ('0.
`RLSEARCH CENTER
`
`EDGEWATI fl, NILW JERSEY
`
`1967
`
`'\/IARCEL DF.1s.lxER, INC., NEW YORK
`|F’R2015-01099
`
`!PR2015-01097
`
`JPRZOT5-01100
`
`IPRZO1 5-01 105
`
`Lupin EX1174
`Page 1
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`

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`COPYRIGHT 6’) 1965 by MARCEL DEKKER, INC.
`
`ALL RIGHTS RESERVED
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`ph<;to..1at, microfilm, or my uzhcr me.‘-Ins, 1.1.111...uL the
`written pcrmissmn of the publisher.
`
`MARCEL DERKER, INC.
`95 Madison Avenue, New York, New York 10016
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`
`1713. 14.11.
`riit. 14.13.
`Fig. 15.6.
`Fig. 15.8.
`Fig. 17.}.
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`‘E1;'.. 17.2.
`Fig. 17.3.
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`Fig. 17.4.
`I-igg. 17.5.
`Fig. 17.7.
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`Fig. 17.8.
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`Fig. 17.‘).
`F13. 17.10.
`F1g. 17.11.
`Fig. 17.2-N.
`Fig. 11.29.
`Fig. 1710.
`Fig. 19 12.
`Fig. 19.14.
`Fig. 21.2.
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`T..1.bIr'. 17 .1.
`
`Tabie !7.‘?.
`
`Table :7 12.
`Tdblt '7 I
`I .
`
`ilutcininson,
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`.\‘-1!1:b:'I:':..~I1'o:: and Related Pl:enumem.r,
`
`lnouc, J. Cafloid Sci, 15, 275
`
`M. J. Schick, J. C.r2No.1'd' .S'c1'., 17, 801 (I962) (Fig. 1).
`Ibid‘., 18, 373 (1963) (I13. 3).
`P. Bccher. :'b1'd., 16, 49 (1961) (Fig. 1).
`1'b1'd.. 17, 325 (l962)(l-13. 2).
`K. Shinoda, T. Nukagawa, B. Tz11...1muchi, and T. kemura, (.'oHo:'da1' Su.«;fac-
`trmrs, 1%]. p. 140 (Fig. 2.27).
`1b1'd., (1. 141 (Fig. 2.28).
`M. Ii. L. Mcflain and F’.
`1955. p. 169 (Fig. 5.14).
`1%. A. Mulley and A. D. Mctcaif, J. Colloid Sc1'., 1'7, 525 (I962) (V33. 2).
`15.13., 17, 526 (l9b2) (F15. J).
`K. Shnnoda, T. Nakaguwu, B. Tamamuchi, and T. lsemura, Cofloidul Surfac-
`mm», 1903, p. l42(Fig. 2.29).
`T. Nakaguwa, K. Kuriyama, and H.
`(I960) (Fig. 5).
`W N M:1r1.1y,1b:'d.,I1,'.‘.3l (l95F)(F1g. 6).
`M. J. Schwk, 1’b1'd.. 17, 812 (196).) (Fig. 7).
`W. N. Maclay, 1'br'd., 11, 277 (l9S6)(Fig.-1).
`B. A. Mull:-y and A. D. Meicall, 1br'd.. 19, 50.‘: (1964) (Fig. 6).
`Ib1'.I., I9. 504 (1964) (F13. 2).
`S. Ross, :'1»r.1., 6, S02 504 (NH) (Fig-.. 1-3).
`E. M;.~..kor. r'!vd., 6, 492 l'|'i‘tl) (Fig I).
`E. Mackor and J. H van :-'r-.- Wa...'s, .hr'cl, 7. 535 (1957) (Figs. 3 and 4).
`J. F. Danivili, K G \. Pa nk‘1.urst, and A. C. Rid1;1J~ .rd, Recem't’rogress1'nSur-
`fme .5‘.-Imce, 1964, D.
`'11
`2).
`T, Nukanaxva, K.
`I(_urI}.1n'|a, and H. lnoue, J’.
`(Table II).
`A. M ‘.1 1nkow1.:h,ib1'd'.. 14, I33 (1‘3S9)("ahlu-:11).
`S. Ru <, rbfch, 0. 500 (1951) (lahlr: ll).
`A, G B1‘0wn_ W. C.'.Thu".1a11, an... J. W. McBain, r’**rd., 8, <02 (L953) (Tubk 1),
`
`(‘fill-11d .Sr.‘l'., 15, 270 ('960)
`
`iv
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`Page 2
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`CHAPTFH.
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`CONl+‘IGURATIl)N OF THE
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`POLYOXYETHYLENE CHAIN IN BLLR
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`.11. Rbsch
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`nnxurscuz nnnrx s-rocluuust-2N 8: cm.
`KnEFELD, GERMANY
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`22.l. Introduction
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`22.2. X-ray Investigations of (lrg.H'IiC ('ltu.1n.—Moleculcs
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`22.3. X-ray Investigations of Ionic Surlactants
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`A. Soaps .
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`B. Miscellaneous lonic Surfactants .
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`22.4. X~Ra,v Investigations of Nonionic Surfactants .
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`A. Polyoxyethylcnes _(and Polyglycols)
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`C. Polyoxyethylenc 1-alt) Acid and Fatty Acid Glycerol Esters
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`D. Polyoxyt.-thylenc Alkylaryl Hjtlfoly Compounds .
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`E. Polyuxycthylene All-ganul and Glycerol I-.tht‘rs .
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`22.5. Speculative Considerations of the Fim-—Structnrc of the
`Polyoxyethylcne Chain and Mrtcromnlecnln Lattice of Nomonic
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`A. Chain Contraction in Pnlyoxyclhylenes .
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`13. Molecular Lattice of Nonionic Snrlhctants .
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`lllvusllgallun of l-me-Structure of Polyoxycthylene Chain by
`Altcrmtte Mt-tliods .
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`A. Electron Microscopy .tntl Electron Diffraction .. .
`ll. Melt Behavior
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`C. Crystallization Phenomena
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`22.6.
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`22.1. INTRODUCTION
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`Studies of polyoxyethylene col-npolrnds in their bulk form have been the sub»
`ject of several recent investigations for the eiucidation of the configuration and
`fine-structure of‘ the polynxyethylene chain. Although it is not yet possible to
`present a definite picture of the structure of the polyoxyethylene chain based on
`these results, importnnt conclusion-. and speculations can be made. The pheno-
`menological part is covered first in Sections 22 . ?. to 22.4, followed by a speculative
`pnrt in .SeCll0I1 22.5. Finally, in Section 22.} an attempt is made to summarize
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`in the light of our present knowlcttge the concepts of the configuration of the
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`754
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`M. RCSCI-4
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`potyoxyethylene chain in polyoxyetliylene or its derivatives, such as nonionic
`surfactants, niafcingi iillowrince tor some inherent u-nertainties.
`Our expeiiincntal knowledge of the “configuration of‘ the polyoxyetliyl-.:ne
`chain in bulk " is inainly based on X-ray invcxtigations». There-ti-re, in thi-. chapter.
`results from X-ray investigations which have coiiti iliutcd so signincantly to the
`general understanding of the conli;;ur.ition and fine--structure of organic chain-
`moiecules are t.'uVered extensively in Sections 22.2 to 22.4. Besides the so—called
`short-di~tance— or wide single-dilfraction techniques, principally the low-angle-
`diflraction patterns have contributed to the characterization (7-fthfi structure and
`dimensions of organic chain molecules. It is well-known that the crystal" or
`cry stnilite structure .l‘- well as the unit cell dimensions in higlwnolecular-weight
`substances can be determined from both wide- and low-angle-ditTr.iction pattern»
`of the same object. Since the X-ray method has only recently been applied more
`extensively to investigations of‘ nonionic surfactants.
`it appears desirable to
`review briefly in Section 223 our extensive knowledge from the preceding X-ray
`iiive-<:ti_r,.itions of ionic surfactants.
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`The investiitation of the fine structure of the polyoxyethylenc chain by at-
`ternate experimental methods is covered in Section 22.6. Another object of U115
`chapter, besides the specific ClI.‘2Ctl~.~:lOl1 ofnonionic surfactants, is also to review
`general concepts applicable to the fine-structure of paraffin chain compounds.
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`12.2. X-RAY INVESTIGATIONS OF ORGANIC CHAIN-MOLECULES
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`Early work has led to the generally accepted ziuag structure of paraffin
`Cililln compounds, in which the centers ofthc C atoms lie in one plane and the
`distance between .ilternate CH2 group: in the backbone chain amounts to 2.‘*1 .-\
`(1-3). This was followed by a complete structural analysis of tie unit cell at
`paraflins (4—7). The parziffin Chains are parallel to the c axis, of the orthorhomliic
`(odd number ofC atom a) unit cell or ofthe monoclinic (even number ofC atomwl
`unit cell with 4| cross-sectional area of 18.5 A’. lateral distances :1, of 5.)’ and
`4.] A, and a distance of 3.5 A between the CH3 groups in the termini! positioiis
`of paratlin-chain layers.
`Figure 22.1 presents the fine-structure of the paraffin chain. It is worth Iliitllll’.
`in connection with the subsequent considerations of polyoxyethylene derivative»
`that Mueller and Shearer in 1923 discussed various eoiifigui ation‘. ofthe parritiin
`chain, namely the ziiuxig, the screw, and A kind of meander structure (8). TM
`schematic ctnfiguration of paraffiii chain layers is illustrated in Figure 22.2,
`together with the l‘CfiECtl:)f1S of the long period of parafiin cliairis.
`Slllltlafly. a laincllar crystal structure comparable to th it of paraflins has been
`found tor fatty .ic-id esters and high-molecula r-weight ketones (0). Although :-unit!
`a l l. logy with parailin cming. exists, a diftereiice in clmn orientation was observed
`with the hl.gl'l‘lT1'3lLCUlc':‘iI'-t‘lF,'ht ketone-. and especially with the Fatty acids, Md
`is illai .trated in 1-ilmrre °? 3. D:mers of C(11'bOx_‘yi gioips (linked by hydri-wen
`bridresl caniiw-I the 'i;,ers of p:iraflT-i r'h..~ins, and the dl.\'-'.ullCt3 I -'tu...:n the l i)t*"l'
`planes corre.ponds to two rat? .:r than one ITwJlCCLIl—|"' leiigth as determined -‘l0i"
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`Page 4
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`CONFIGURATION OF THE POLYOXYETHYLENE CHAIN
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`755
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`H c
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`H
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`H
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`cg- 1-
`04%c\i
`C_:;!_ J
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`C H
`H
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`C H
`H
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`H
`C
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`H
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`HC
`H
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`H
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`H
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`Fig. 22.1. Fmc structure of paraffin ¢.h.m1.
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`‘\
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`‘N.
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`‘\
`Li??|JWC
`*m¢urr
`WW!
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`Fig. 22.2. Schematic ar1'2ar;:n1enl of paraffin ..-
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`n9.
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`756
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`M. ROSCH
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`WM
`/W
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`Fig. 22.3. Schematic arrangement of fatty acid chains.
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`the long spacings. Moreover, the inclined (tilted) orientation of the molecules
`to the layer plane in contrast to the normal orientation observed with paraffins
`is also reflected in these long spacings. The inclination of the fatty acid chains
`to the layer plane depends on the fatty acids and their pretreatment for investi—
`gation (10). These findings constitute the basis for the interpretation of .‘(—ray
`patterns of ionic surfactants as shown in Section 22.3.
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`22.3. X-RAY INVESTIGATIONS OF IONIC SURFACTANTS
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`A. Soaps
`
`Von Sydow (11) and Abrahamson (12) have recently given an exhaustive
`treatment of the solid-state behavior of normal- and long-branched-chain IZIEIY
`acids. Thev; articles also include 4 review of earlier crystal-structure investiga-
`tions of fatty acids.
`It is generally accepted (13,174) that soap molecules in the solid state are‘ in-
`clined to the lattice plane with their ionic layers in pairs, which is analogous to
`the orientation of‘ fatty acids as shown in Figure 22.3. Mixed crystals have also
`been obscr-.ed Wltll soap». For C)\.a.lI1pIC, Hess and Kiessig (15) found mixed
`crystals in mixtures of soaps differing in chain length, such as the potassium
`salts of oleic, Laurie, and capric acids, illustrated sohematcally in Figure 2.~’."r»
`Alternatively, in mixed cry. tals ‘7l1‘£1lgi‘l. -soap chains may penetrate in a inannrrt
`shown in Figure '3'.‘ 5. The latter is hmi‘.t.d to the case in which the anf'l€‘v
`“i
`inclination are dependent on the ~ ‘rip l‘E1I.l0S. and the uniformity of the mist-<1
`ci'ystaI-.t varies a:. ; l‘u1‘.ct.on of the mixing ratios.
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`CONFIGURATION OF THE POLYOXYETHYLENE CHAIN
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`757
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`W//I
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`Ff3- 214- Mixed-crystal foriiiution by soaps of different chain lcn:_;th (If).
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`//// W
`M
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`Fig. 22.5. Mixed-crystal formation by straiglit-chain soaps of different chain length.
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`The arrangement of dibasic fatty acids and their soaps is schematically pre-
`sented in Figure 22.6 (15,16). Formation of mixed crystals is ruled out, because
`
`//I
`Z /1
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`Fig. 22.6. Crystal formation by dibaséc acids (15,16).
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`the paired terminal carboxyl groups are linked in the lattice planes with each
`other through paraffin chains. This was confirmed by the results of Hess and
`Ki-essig (15) on mixtures of the potassium salts of adipic, suberic, sebacic, and
`hexadecanoic dicarboxylic acids.
`A few remarks must be added about the short spacings, i.e., the lateral dis-
`tance 4, between the hydrocarbon chains in fatty acids and their soaps. Initial
`work on fatty acids, fatty acid esters, and their hornologs showed uniform ds
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`753
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`M. ROSCH
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`values from 3.7 to 4.1 A (8,17,!8). For example, Hess and co-workers (18)
`observed n‘, values of 4.0 and 4.0 A for solid soaps. Likewise, Ross and McBain
`found for hexanolarnine oleate a a’, value uf'4.5 A (10).
`‘land and de Boer (20) deduced from their theoretical treatment that the
`lateral distances in paraffins, soaps, and related compounds are dependent on
`chain length as a result of the increasing van der Waals forces. It is apparent
`from all these data that general agreement in the lateral distances of soaps de-
`rived from wide-angle X~ray—difl‘raction patterns exists, namely,
`:1’, =4.6 to
`4.8 or 4.4 to 4.3 A, respectively.
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`8. Miscellaneous Ionic Surfactants
`
`A number of papers have also been published on X-ray investigations of ionic
`surfactants, such as sodium n-alkylsulfates, sodium n-alkylsnlfonates, dodecyl—
`pyridinium chloride, cetylpyridinium chloride, and dodecyltriniethylammonium
`chloride (I3,14,18,21—28). However, many of these studies have been carried
`out on solutions. in contrast, Staulf (21) has studied crystalline sodium ll‘
`tetradccylsulfate. The long spacings amounted to 38.2 A, the short spacings to
`4.55 and 3.98 A. These lateral distances are comparable to those observed with
`soaps. The long distance of 33.2 A was stnailer than twice the H10lCClli‘.il' exn:n—
`sion of n-tetradecylsulfate. i.e., 46A neglecting 3.5 A between terminal (‘H_,
`groups. Consequently, the mtetradecylsulfate molecules must be inclined to the
`lattice plane in analogy with the soap molecules.
`The crystal structure of soaps and ionic surfactants thus is very similar to that
`of fatty acids. The zigzag chains are arranged in lamellar form with the terminal
`CH3 and polar groups being inclined (tilted) to the lattice plane. The angle of
`inclination is dependent on the chain length and the experimental conditions.
`i.e., pressure, temperature, etc. This type of lamellar orientation of soap mol-
`ecules with their ionic layers in pairs explains why the long spacings must be
`larger than d, (=: single molecular extension), bill smaller than 2d,. Two constant
`lateral distances are observed (1,, and d,, with 4.5 to 4.8 A and 4.0 to 4.3 A.
`respectively.
`The cohesion between the soap chains in the molecular lattice is .".ll1'lbulL‘d
`to intermolecular forces, such as the van der Waala forces operatimx betwccfl
`the hydrocarbon chains and the dipole forces, or hydrogen bridges, respectively’.
`with fatty acids, operating between the polar groups. The latter forces :I|\'0
`contribute to the pairing of the soap lamellae and to the inclination of the will
`molecules to the lattice plane.
`After this brief summary of our knowledge of '~.)up utrticture, let as non dis-e
`cuss the finding-. of X-ray investigation. of polyoxyethyjene and its derivati\-‘cw
`
`12.4. X-RAY INVESTIGATIONS OF NONIONIC SURFACTANTS
`
`A. Polyoxyethylcnes (and Polyglycols)
`
`.url"-actants,
`Although this gioup of compour-is ,:av*.n0t be classed as
`been included in this chapter because it foins tl
`-
`'.yd1ophilic group Hi
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`CONFIGURATION OF THE POLYOXYETHYLENE CHAIN
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`759
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`the findin rm from X-rriy investigations of
`nonionic surfactants. Furthermore,
`polyoxyethylenes and poiyglycol-, have led to important conclusions on the fine-
`structure of its surface-active derivatives.
`For completely anhydrous conditions. Roithner (29) Originally postulated the
`formation of cyclic polymerizates of ethylene (.“(lCiBS such as dioxane. However,
`in practice polymeric chain. with terminal hydioxyi ggroups, i.e., polyethylene
`izlycols, are ohtaiizcd, since either the conditions are not completely anhydrous
`or the starting materials used in the preparation of ethylene oxide adducts
`contain hydroxyl groups. Reference will be made later to the fact that formation
`of ethylene oxide dihydrates may also be achieved by anhydrous polymerization.
`These dihydrates were studied in the first X-ray investigation by Sauter 130).
`Barnes and Ross (31) and H iblwert and Perry (32) have confirmed the analogy
`between the Xuray data of polyoxyethylencs and polyethylene glycols. Therefore,
`it appears justified with hi;-her hornologs to consider the fine structure of the
`polyoxyethylene chain alone if we neglect the terminai hydroxyl groups. This
`has been done in this chapter.
`Staudinger (33) postulated two structures for polyoxyethylene: the zigzag and
`the meander configuration. On the basis of‘ solution-viscosity and melting-point
`data,
`the meander configuration appeared to be the more probable one.
`Staudinger found from viscosity measurements 21 Km constant _J; smaller than
`calculated. From this it follows that at a higher degree of polymerization the
`chain contracts. Up to st degree of polymerization of 9, the chain exhibits a
`;z.i,w.i;», structure, whereas at higher degree of polymerization a meander structure
`is observed. As an explanation Staudinger suggested that the oxygen atoms of
`the main polyoxyethylene chain attract each other. The magnitude of this
`attraction increases to such an extent that beyond a degree of polymerization of
`I} it leads. to chain contraction. Rtiscli (34) has attempted to interpret this chain
`contraction of the polyoxyethylene chain in term. oi‘ an array of equidistant
`:mtipar;illel dipoles.
`Staudinger’s model of the polyoxyethylcne meander chain is relatively simple,
`as shown in Figure 22.7. Based on his study of polyoxyethylenes in the MW
`
`/°\
`
`O
`
`\
`
`O
`/ \
`
`0
`/ \
`
`H
`
`H C
`
`€2fb£H H‘£‘H2H2ti?:HEH2 H2!-it
`2 H
`C
`/ 2*$\O/
`2 2\o/ 2 2\o/ 2
`
`Fig. 22.7. Meander coitfigtltdtion of poiyoxyetliylene chain (33).
`
`range ot"’.400 to 100,000, Saute-i (W) hm con tructed a meander chain exhibiting
`the usual valence an-ales and the tree l'0i.E1liuI1 around the main valence axes. He
`]“rt‘*--.:I:t6kl a (iCl.!li€U picture of the str:1in—free puiyoxyethylene chain and its
`packing in the macromoiect:7ar lattice; the monoclinic unit cell consisting of 4
`1.‘-olyoxycthylene meander chains each with 9 oxycthyfeiie units. Similarly,
`
`Page 9
`
`

`
`760
`
`M. RUSCH
`
`lower—n1olecular-weight CARBOWAX 6000
`Price and Kilb (35) found with rt
`a monoclinic unit cell, but
`t‘Oi.L.siSlil'lg of 78 oxyethyiene units in contrast
`to .‘-}:‘.uter’:. 36. Thut, only 3 twtated nxyetliylenc clmns are present in the unit
`cell. Price and Kilb as well a« gamer found the same ldenti-‘y periods of 19.5 A
`for both main valence chains.
`
`According to Sauter, the position of each oxyetliylene group along the chain
`1.. .omewh::t twisted from the neighboring one. Thus,
`the main chain appearx
`to be twisted with every Iirst and with group occunymg the identical position.
`In the rnonuclinic unit cell
`the total length of the twuted meander chain of 9
`oxycthylune unit:
`is 19.5 A, and, hence,
`the length per oxyethylcne unit-
`i\
`2.l7A. In contrast, Stuudinger lias assigned to the meander type of units .1
`lrenyth of L9 A .tHd a width of4 A, to the zigzag units a iength of 3.5 A and 2»
`width of 2.5 4.
`
`The plnnar presentrititvn of the zigzag chain and of Suuter‘s rnraancleb
`type polyoxyctliyl.-ma chain as lirst gziven by Kehrcn and Rt‘)-.ch is reproduced
`
`in ligure12.8 (36). In this diagram correctvalence mglea,atomicradii, and
`
`‘
`
`I
`
`Fg. 21.8. 1.i«;zas' and in. mdert =nti'.urn
`
`In of p..'ynx_i- lh‘."'JC Chain ” ,L
`
`Page 10
`
`

`
`CONFIGURATION OF THE POLYOXYETHYLENE CHAN
`
`761
`
`in the
`un.t.~.
`the ('xjeti‘.y[r"i.:
`of‘
`ham: been usul. The lenrgth
`dl.‘:i;€lI]("E"~‘.
`meander-type chains amounts to 1.8 A, but in tin; zigzag chains it varies from
`3.38 to 3.53 A.The latter value of ~3.5 A is in live w!r.l*- S=..uwing+-r’sd'1ta. On
`
`.I.VCl'aglfl}' Staudinger, Sautcr, and Kehren’-; value tor the oxyethylcne lll'll[$
`in the meandcmypc chain-. a value of 1.96 or «-2 A in obtained.
`lmvc aided
`These findings about the po]y0!tyL"h_)ie1'1(: clunn and it. unit cell
`the speculative interpretations of |'10iy0‘(\.t:tl'._) lcne CiCI'tV£1Ii\"s.‘.;-, as will be shown
`in Section 22.5. Let us consider once more the ideal ‘.°0t‘HI.'~ «~F both polyoxyeth_v-
`lane I.J()I1figl.lr‘.1ll-.)n5. Since the planar models in 1-igurcs 22.7 and 242% yield only
`an incomplete picture of three-dimensional configurations, Stuart—Bricgleb
`atomic models are included in Figure 7.2.9. Both models 211:‘ vainly distingtmlied.
`The zigzag model may be simply transluuned by a twist into the close-packed
`
`-nu‘;
`
` r
`
`A
`
`t
`
`I
`
`"
`
`‘
`
`4"’
`‘
`f’°.i‘a)_
`
`l‘
`\
`1
`
`’
`
`t
`
`.
`
`1
`
`l
`
`‘I.
`
`‘S
`
`..w
`
`mg. 22.9. SlI.!.'!rt—Brieg'eh atom“ moth ~‘ of the ‘hurt and ineanfer .' ntiguralion of poly-
`my ' rm ic r:h.ti'
`
`Page 11
`
`‘
`
`

`
`762
`
`M. ROSCH
`
`meander model without breaking the chain. It is evident from Figure 22.9 that
`the zigzag model consists of 10 -ntyethylene units, whereas the meander model
`consists of 12. This conforms with Staudiiir-,er’s postulate ofthe transition ofthe
`polyoxyethylene chain around 9 oxyethylene units or Kehren and R6sch's
`postulate of the transition between 9 and 12 oxyethyiene units with poly-
`oxyethylene derivatives.
`It is concluded that the polyoxyethylene chain exists in the zigzag configuration
`at low degrees of polymemation and in the meander configuration ;it high
`degree of polymerization. In the zigzag chain the length and width of the
`oxycthylene unit umutlnts to 3.5 and 2.5 A, respectively;
`the corresponding
`values in the meander chain are 2 and 4 A.
`‘
`
`Finally, it must be resolved whether this transformation shown by the results
`of three independent investigations is generally applicable to the bulk behavior
`of polyoxyetllylenes.
`(a) Staiidinger studied polyoxyethyleiies in solution;
`(b) Saucer used high-1noleculanweight polyoxyethylenes in the solid state
`covering an MW range from 7400 to l00,000 (or a degree of polymerization
`range from 55 to 2300); (9) Kehren and Rosch studied polyoxyethylene fatty
`alcohols in the solid state. However, liiessig (37) recently reported an invest-
`ig;ition- of
`low-molerular weight polyoxyethylenes covering a
`range at
`molecular \\‘L‘|_!',h[S of 1000, 1500, and 4000 (or degrees of polymerization of 23.
`34, and 91). Sharp low-an_:_1le X-ray diffraction patterns were observed with
`Cu-K 1 as well as Co-K or rzitliation in two or three arrays for these medium-chairr
`length distribution... These patterns are considered basediffractions. With increas-
`ing rriolecular v.-eight. beyond this medium range of 1000 to 4000 the diffractioii
`patterns broaden and become meal-te.r. Kie:.sigz's correlation between moieciilzir
`weight, average flfif-".](’E‘ of polymerization, and calculated and observed main
`lattice plane distances is given in Table 22.]. Sauter’s value of 2.17 A is used for
`
`TABLE 22. 1
`
`Average (‘twain Length I and Lattice Plane
`Distances J of P0]yOXyCll1‘,i<.'J'1l;'. (37)
`
`MW
`
`DP
`
`(AA),
`NA) =
`DP :- 2.17 observed
`
`1000
`I500
`4000
`
`22.7
`34.]
`90.3
`
`49.3
`73 .9
`I 97
`
`76
`lCD~-I i0
`160-4 90
`
`In general only -in
`the length of the oxyethy'ere unit in the ':l1BanC.lB1'1T:0(Li€ii.
`approximate 3_:i"C€lflCI‘I
`bi tween HA; and (HA) has been observed; the dr--
`ercp.-incies are large. - iur MW 1000 an.l 1500. It is evident from table 72.2 that
`agreement is 0bi.:iI'It‘l only if it 11-‘ models are taken into consideration. This
`table inclur‘:-s the chain length I calculated both in terms ofthe ineaintler ni- ~l*‘»l
`
`Page 12
`
`

`
`CONHGURATION OF THE POLYOXYETHYLENE CHNN
`
`763
`
`TABLE 22.2.
`
`Average Chain l.-rngth and Long Spacing of
`Potyox) ethylene
`
`MW
`
`1000
`L500
`4000
`
`DP
`
`22.7
`34.l
`90.8
`
`l(A)
`lfA)-
`DP ;- 2.0 D!’ -- ‘.5
`
`dfAL
`observed
`
`45.4
`68.2
`18113
`
`70.5
`H9.-4
`3l7»"l
`
`75
`I00-I l0
`l60—l9O
`
`with an oxyethylene unit of 2.0 A and in terms of the zigzag model with an
`miyethylenc unit of 3.5 A. Thus, agreement between I (A) and d(A) is obtained
`it one assumed the zigzag structure at low degree of polymerization of 22.7
`and 34.1 and the meander structure at high degree of polymerization of 00.9.
`ln equirnolar mixtures of polyoxyetliylene of 1000 and 1500 molecular-
`weight species, Kiessig (37) observed a low-angle diffraction pattern with d,
`‘)3 .\. For a meander chain model :1’, ; 56.8 A has been calculated, whereas
`;i\-turning a zigzag chain (I, =97.-I A. This agrees with ascribing the zigzag
`model to both components as shown in Table 22.2.
`it is concluded that the transformation of the polyoxycthylene chain in the
`range of 9 to 12 degrees of polymerization is not generally applicable to the bulk
`behavior of polyoxyethylcnes. This llict has also been considered in recent work
`by Kehren and Rtisch on polyoxyethylene octadecanols (J0).
`
`B. Polypropylene Oxide
`
`the ii~:~.f. reference to polypropylene oxide was made by Staudinger (33). This
`mmpound has gained prominence as it component of polyoxyalkylene block
`k.‘tJpOlyll"lL!l"~, such as the PLURONICS, which have been treated in Chapter if).
`A iew observations about its crystal-structure behavior are given below.
`in general. polypropylene oxide crystallizes with greater difficulty than poly-
`oityethylene. Staudinger found that the methyl groups of the polypropylene
`oxide chain fit better into the empty spaces of the meander configuration than
`into the zig zag configuration. Roseh (38; noted resistance tram steric hindrance
`when trying to twist the zigzag Stuart-Briegleb model into the meander form.
`Natta et al. (39) have reported X-ray patterns of cold-drawn crystalline poly-
`propylene oxide fibers with an identity period of 7.16 A. This value conforms
`with a valence angle of 109"30' and bond distances for C-0 of‘ 1.43 A and (,«C
`of L54 A. These authors claim the unit cell to be orthorhombic with distances
`
`of 10.52 and 4.67 A, which encompasses two almost centered chains. Calculated
`ilfld observed ClCl‘l‘\lIleS are in good Cl}',l'eell1Cl'll.
`Shari belfn and Hughes (40) and Stanley and Litt (4!) arrived at similar con-
`irliuions. However, the latter claim that the orthorhombic unit cell encowpa ;s~.:S
`three polypropylene oxide chains. These form twisted nonp‘:.inar zigzag chains
`in which the methyl groups alternate between the oxygen and rnetliy'ene groups
`
`Page13
`
`1"-'
`
`|-
`
`

`
`764
`
`M. RCSCH
`
`of the neighboring chain. The authors do not exclude the possibility of the exist-
`ence of optically active d,l unit cells. The-.c contentions conform with Rbsch’s
`{38) conclusion that steric l1'.|'lCll'fll'lCC leads to a nonplanar .’l;C£t'.!g chain and
`excludes formation ol .: ll"l€t1ndCl‘(.‘l'l:.lI]. So far the effect of degree of‘polymeriza-
`tion on the configurations ha‘. not yet been studied.
`
`C. Polyoxyethylene Fatty Acid and Fatty Acid Glycerol Esters
`
`There .tI‘f.‘ only a few known investigritions dealing with these nonmnic sur-
`factants (42-45). Marsdcn and 'vIcB.un have rep0l‘lCd in a study of supercooled
`dtethylene glycol-tnonolaurate (Glyco Products, inc.) long spacings lfl the range
`of 40 to 49 A (42,43). For this compound the length ol the zigzag chain is cal-
`culutt-d as being 22.7 A. A value of 48.9 A is computed for the lung spacings
`by taking twice the molecular length together with a distnncc of 5.5 A between
`the terminal (“H3 of the fatty acid chains, which is comp.:t.ibIe to the experi-
`mentally nbserycd value of 46 to 49 A. In COTltl'd\'l to tht inclined orientation
`characteristic for soaps. diethylene glycol monolaurate orients vertically tn the
`lattice plane. Thexc authors lound a surprisingly long spacing of 39.5 A for
`another technical glycerol monolnurate, which exceeds Mall-tin and Shui'lmg.:),"s
`(44) value tor the pure simple by 1.2 A. Polyctliylcne glycol 400 monolauratc
`has also been investigated in the litguid-crystalline state.
`Only one reference to the rt‘, distances of polyoxyethylene exters in bulk has
`been published by Doscher et al. (45). For a commercial
`tall «)il+ 10 F0
`addiict tRF.NEX) they found :15 -— 3.67 and 4.69 A, which is comparable to the
`d, value of soups.
`
`D. Polyoxyethylene Alkylaryl Hydroxy Compounds
`
`Initial work by Kiessit; (I3) dealt with the X-ray-diffraction patterns ol‘ ll
`technical diisohexylphcnol + 20 E0 adduct
`(IGEPALJ
`I-'t'om the Dehu-
`Scherrer first and second-order rings,
`:1 cf,
`long spacing of 80.3 A was dctcr~
`mined. Amtminy, a straight (I, zirzag Lllflln (with 3.5-A [B‘I'II'|ll1.tl distances},
`:1
`single molecular length of 82 A or IJ double molecular length ol I68 \ has hcvn
`calculated. The xingle molecular length is in agreement with the observed lontl
`spacing given above. On the othet‘ hand assuming rt meander chain, a vlnfllfi
`molecular length of Sl A .-and a double rnolccular length of 105A liavc bwn
`calculated. Thus,
`the .in_:-ie igtag molecular length ll'1'lilC oolyoxyethylcnv
`chain correuponds to a first approximation to Kiessig‘-; it" g pacing lound for
`the IGEPAL.
`
`He--~. ct al. (40) dctcrrvincd a :11 long '~'l'lClI}f’ of 97 A for a dotiecylphenwi. 1"‘
`dodecvlcre' »>l, +30 EO adduct HGL PAL,. A» .ume.nq n strai_'-;t zigzag st= 1;.-,tut-c
`tc '-"ii:--'; n‘-olecular length of lib A he» been cttlct l.--ted, wherct;
`51' ceminy.
`~!
`mc'1'lde structure 79 A W1‘
`-ibt ~‘ned. lror» n cnnpar. on l*:=twr°:en ll rt resui'~
`til the two l3ol)to:<)’etl1}'lc'
`. ali<* “aht:
`ll‘,
`it
`i; tlcd ed that there is no =HHPl"
`way to cshnlish structural I-‘lull ll}
`ins lur I mionic St.-'l:1C=.’antS. For c\tan'Pl"-
`
`Page 14
`
`

`
`CONFIGURATION OF THE POLYOXYETP YLENE Cl-lAiN
`
`765
`
`.i correlation between a .~eii;;lr rirvriig lTlC‘lCLUl£1I leigtli of 125 A and the observed
`
`I very tilted orientation
`gdluc at 9! A with the ri?i.y'phcnu; . + 30 E0, siir*'-\cst:-
`ulthe l.imell.ie tn the li:t.ll.!C!‘ plane. In contrast w:th the above diisnliexylphcnnl +
`30 E0 V{"1‘[lCtil orientation ol. the lameilae to the i.‘[tit.c planes w-its conri.,len_=.d
`lbilfilbien It is dillicult to coniprehend nah-,, on lent-rhening the nolyoxyetltg lene
`chain of the alkylphenol-.. 21 <:l:.~.np_: in ()I‘lCI'll..|llUf1 of the lamellate to the ldlllcc
`plane was 0bSCr"w€d.-Willi
`the ll”(ylpllF'l'|Ul + 30 E0 acldisct the double molecular
`length is obviously completely out of the rang: of compamon with the long
`spacing of 97 A.
`Kiessig (4/) presents the first COnlt')."I1:~~)I'l between two polyoxyetliylcnc
`;lll\'_\'lpl'!CI'tOi‘w with identical diisnliexylplicnol hydrophobic nroup an .i function
`otethylene oxide chuiiilength. [)il'w<.JhCX_\'ipl"lCfl0I
`- 201:0 exhibitsaloiiguprtcing
`of 80.3 A, whereas (.lilSOhE.'\_\rlpl1€.’l'l0l
`-
`:0 E0 .\7|VLl..r 99.6 A. Hence ri dillerencc
`oi‘ IO oxycthylene units corresponds to J,
`-r 19.3 A or an increase of L9 A per
`t').\'_‘\t.‘thyiCl1€ unit. This is in line with St.=udiiisver‘s value of‘ 1.9 A for the length
`or‘ the meander vxycthyiene unit or to the 'tvei'.igt: value of 2 A taken from the
`literature for the meander oxyc.-thylene unit.
`it ha\ been shown that the long spacing J, = 80.3 A corresponds to the single
`zigzag molecular length of diisoliexylt-liciiul + 20 H).
`In COIlll‘i’.l'«l,
`the long:
`spacing d,
`09.6 A ul d1lhiil1=‘X)'lphcl10l + .30 E0 corresponds analiigouslt with
`the dodecylphenol + 30 1:0 neither to the Sll:i'iC £l_1;.£11_F
`inoleciilar lerigth of
`II? A nor to the ]]':t":tl'lCl(‘.I' molecular length of )2 A. Since C0!1.\lkiCl'ii[lOIl\ of‘
`
`it is apparent that these
`.<.u_s»_i*.e.teil the meander turm For both liomnlngs.
`Ad.
`.\lt'llC[1J!'£!l relt1tion.=.liip'« are complex, as. will be discussed in Section ‘.2.4,E. In
`ii later investigation Hes’ Lind l(7msig I D) report-ed a long spacing ri’,
`= 89.6 A
`for mixtures of equal weights of tliisohr-wlplienol +20 and 30 H), which
`L'tJnlUTTn\ well with the theoretical -value ot 88.4 A.
`
`t- 9 to 10 E0
`investigated ;i-I-it-:ty~phenol
`Marsden and McBain (42.43)
`(‘TRITON X-I00). Since l.hl\ compound 1‘~ liquid it rooir. temperature and rend-
`ers no ditTr-action patterns, the long .\p1lCll‘.Q”!S were determined on LI chilled solid
`specimen and ii‘, .lmtiilnlCd L0 50 A il'll"-I i\ in line with the c:ilcu!.itcd molecular
`length ot‘ St A. ln aralogy with diisol.e.xvlpheni~l + 30 L0 the experimentally
`ulincrved long S]“.l(‘lIlg (I,
`is in agreement with the i..il.i.- crilculated for tlzc tirnple
`zigieag molecule. However, since the latr!1Cll{tl' zirrangemetit of single molecules
`is improbable, another crystal—l-attice arrangzcment proposed by lxehren .-ind
`Rosch (48)
`a
`i SITOWTI in l-igure 22.l0 must alw he considered The ]JI'ESCliL.C of
`tliv henzeie ring in .v molecule of a non?-mic 5-..ililCl.&ll’1iC.".tiSC." ti‘.-. hydrophobic
`and hydrophilic parts of the riolectiie to il‘.’t‘!'0Ll(, and, ciinxeituently resulting
`H] a lon:' spaci.-'._' of 43.8 A for nine u;.yt'.'h_\«icne units :43). With it) rixyctlyjene
`llllits
`the long spacing would be ll1ClCtt.\t’l
`to 52.3 A. Both VI‘.lUC\, and
`partici.l_-v.rly thei
`.:verat'_c.
`’1"B in go .1 al3f'tit.‘l?‘f:f‘ll with the ".}'1Cl