topochemical polymerization of monomers with conjugated triple bonds

Die Makromolekulare Chemie 154 (1972) 35--48

Institut fur Physikalische Chemie der Universitat Mainz, Sonderforschungsbereich Chemie, Physik und biologische Funktionen dcr Makromolekule, Mainz-Darmstadt

Topochemical Yolymerizatioii of Monomers with Conjugated Triple Bonds *)

G. WEGNER

Main Lecture, Symposium M-14, IUPAC, Boston, July 1971 **)

(Eingegangen am 8. September 1971)

SUMMARY: Solid-state polymerization of monomers with conjugated triple bonds turns out to be

a versatile method for synthesis of crystalline polymers of high molecular weight exhibiting a fully conjugated backbone. The reaction is best described as an 1.4-addition polymerization of the conjugated triple bonds giving rise to a polymer with three cumulated double bonds per repeating unit. The all-trans configuration of the substitucnts is a consequence of the solid-state reaction mechanism and is already predetermined by the packing of the molecules in the monomer lattice. I t was shown by X-ray analysis in the case of poly(2.4- hexadiin-1.6-diol-bis-phenylurethane) that the polymer diacetylenes can be described by either a butatriene structure or by a mesomeric en-in-structure.

Polymerization of the colorless monomer crystals is achieved by irradiation with UV- or high-energy radiation or by simply annealing the monomer crystals below their melting point. Deep red, blue or black polymer crystals are obtained exhibiting strong dichroism with the fibre axis as the direction of main absorption. These crystals possess semiconducting properties (EA = 0.6-1.0 eV, depending on the substituents a t the conjugated backbone).

ZUSAMMENFASSUNG: Die Festkorperpolymerisation von Monomeren mit konjugierten Dreifachbindungen ist

eine vielseitige und einfache Methode zur Synthese von kristallinen Polymeren mit einer vollkommen konjugierten Hauptkette und hohem Molekulargewicht. Die Polymerisation lal3t sich am besten als eine 1.4-Additionsreaktion der konjugierten Dreifachbindungen beschreiben. Dabei entsteht ein Polymeres mit 3 kumulierten Doppelbindungen pro Grund- baustein. Die trans-Konfiguration der Substituenten ergibt sich zwanglos aus dem Mecha- nismus der Festkorperpolyrnerisation und wird durch die Packung der Monomermolekiile im Kristallgitter vorherbestimmt. Aufgrund der Strukturdaten aus einer Rontgenstruktur- analyse des Polymeren aus 2.4-Hexadiin-1.6-diol-bis-phenylurethan muR angenommen

* ) Part VI of the Series “Topochemical Reactions of Monomers with Conjugated Triple

**) XXIII IUPAC Symposium on Macromolecular Chemistry, Boston, 1971 (Macromole- Bonds”.

cular Preprint. Vol. 11, p. 908).

35

G. WEGNER

werden, da13 die polymeren Diacetylene entweder durch die Butatrien-Struktur oder eine mesomere en-in-Struktur beschrieben werden konnen. Die Polymerisation der farblosen

Monomerkristalle wird durch Bestrahlung mit UV- oder energiereicher Strahlung oder aber durch Tempern der Monomerkristalle unterhalb ihres Schmelzpunktes bewirkt. Tief rot, blau oder schwarz gefarbte Polymerkristalle werden dabei erhalten, die einen starken Dichroismus aufweisen. Die Faserachse ist die Richtung der Hauptabsorption. Die Polymerkristalle sind Halbleiter. Die Aktivierungsenergie der Leitfahigkeit liegt in Abhangigkeit von den Substituenten an der konjugierten Hauptkette bei 0,6-1,0 eV.

I. Introduction

The technique of solid-state polymerization has developed from a mere scientific curiosity to a promising tool of preparative polymer chemistry during the period of the last 10 years. One of the reasons for current interest in these solid-state or topochemical polymerizations is due to the fact that they provide a means of direct synthesis of polymer single-crystals which in many cases exhibit an extended chain morpho- logy1-3). Another important feature of such topochemical polyreactions is tha t stereospecific polymer synthesis can be achieved without any catalyst, making use of the packing properties of organic molecules within their lattice only. A good example for such lattice-controlled polymerizations is the synthesis of polymers with the cyclobutane ring in the main-chain, starting from derivatives of p-phenylene-bis-acrylic acid which was reported recently by HASEGAWA et al .495). This is a logi- cal extension of the work of SCHMIDT et al. on the solid-state dimeriza- tion of cinnamic acidse) into polymer chemistry, and polymers having stereospecific arrangement of the substituents a t the cyclobutane ring are obtained. Such polymers cannot be prepared by usual polymerization techniques in solution.

The subject of this report is the lattice-controlled polymerization of monomers with two conjugated triEle bonds as a structural element. This polymerization turned out to be a versatile method of synthesis of crystalline polymers exhibiting a fully conjugated main-chain. It is surprising tha t solid-state reactivity of compounds with conjugated triple-bonds has been known to organic chemists for almost one hundred years7), but i t was only recently tha t the true nature of the resulting

36

Topochernical Polymerization of Monomers with Conjugated Triple Bonds

product could be elucidated. This is quite strange since there are many reports on the “spontaneous” polymerization of compounds with conjugated triple bonds*-11). It must be admitted, however, that the ex- treme insolubility of the resulting polymers must have been a serious barrier against any attempt to obtain deeper insight into the mechanism of this solid-state reaction (e.g.11)).

The first attempt to elucidate the structure of the reaction products of the solid-state polymerization of conjugated diacetylenes was reported by S E H E R ~ ~ ) in 1954. He isolated the polymerization products of some diindicarboxylic acids and concluded from the investigation of their thermal decomposition products tha t the polymerization could be described according to Eq. (1)

R R R < - .-m::: ...

R R R R

R = -(CH2),,-C02H n = 0, 1 , 2, ...

This concept was taken over by B O H L M A N N ~ ~ ) and was subsequently introduced into many reviews on solid-state polymerization (e.g. 1 9 1 3 ) ) .

The formulation of Eq. (1) is not in agreement, however, with the state- ment of many authors tha t the shape of the monomer crystals does not change during polymerization. If Eq. (1) was correct, a considerable contraction of the crystal in the direction of propagation should occur which, finally, would be destructive to the lattice and shape of the crystal. Therefore, Eq. (1) cannot be correct, since i t neglects morphological features which are essential to the understanding of solid-state processes.

11. Preparation and Structure of the Polymers

Many compounds possessing two conjugated triple bonds are highly reactive in the solid state, but they are not reactive if dissolved or lique- fied. Deeply colored crystalline polymers are formed by irradiating the colorless crystals of the reactive compounds by UV- or high-energy radiation or by simply annealing the monomer crystals a t elevated temperatures below their melting points.

A good example is the polymerization of 2.4-hexadiin-1.6-diol-bis- phenylurethane (I, Eq. (2)) (mp 172 “C). This monomer crystallizes from

37

G. WECNER

different solvents in different modifications only one of which shows a very high solid-state reactivity14). This modification is obtained by crystallizing from a mixture of hot dioxane and water as colorless, needle-like crystals. It contains 1/2 mole of dioxane per mole of the monomer. If these crystals are annealed a t 110 "C for a period of 24 hours or are irradiated with UV-light (A < 300 wp) for some hours, copper colored polymer crystals are obtained with a 95 yo yield. The residual monomer can be cxtracted by hot dioxane or similar solvents, leaving behind a polymer with the original shapc of the monomer crystals still containing 1/2 mole of dioxane per mols of base units (Fig. 1). The polymer crystals are soluble only in hot: hexamethylphosphoricacid tris- amide (HMPA) with some decomposition. They show metallic brilliancy

Fig. 1. Crystals of the polymer from 2.4- hexadiin -1.6 -diol- bis-phenylurethane as polymerized from the modification containing 1/2 mole of dioxane per mole of

the monomer

and are highly dichroic with the needle axis as the direction of main absorption. They also show fibrillization parallel to the needle axis and considerable mechanical strength within the direction of this axis.

R-C-C-C-C-R

R R-C-C-CIC-R h . V "'\ /R

___t c=c=c=c \ a b / c = c = c= c

\c / / \ ...

/R R-C=C-C-C-R orheat /

R c = c = c = c R

111 R, e.g.

I V

H- Of CHZ- CH,-CWj-CH,-C- C- C s C-CH,+O-CH,-CH*+-O- H VI

38

Topochemical Polymerization of Monomers with Conjugated Triple Bonds

The observations led us to the conclusion, which was later fully confirmed by detailed X-ray structure analysis, that the polymerization gives rise to polymer chains parallel to the axis of maximum elongation of the monomer crystals and to a main-chain which represents a strong chromophor. Bearing in mind the chemical structure of the monomer, and making use of current knowledge on packing properiies of organic molecules within their lattice15) a reasonable model of the polymerization process could be developed according to Eq. (2)14716).

The reaction is best described as a 1.4-addition polymerization of the conjugated triple bonds yielding a polymer with three cumulated double bonds per repeating unit and a fully conjugated main-chain (111, Eq. (2)). X-ray structure analysis of this polymer showed that the assumed model was correct but can be refined by describing the polymer by the mesomeric formula IV (Eq. (2)). This is concluded from the experimentally obtained values of the bond lengths of the three different types of bonds within the main-chain: a = 1.21 A, b = 1.41 A, c = 1.36 A1@.

Tab. 1. Solid-state reactivity of diacetylenes as depending on the nature of the substituents a t the conjugated triple bonds; general structure : R-CEC-C~C-R

Substituent R

-CH2Ph -CHz-OH -CHZ-OCOPh - CH2- OC02Ph -CHp-OCO-<I)

COzH -CHZ-OCONHPh - CH2- OCONH-a-Naphthyl -CH2-OCONHC4Hp - CH2- OSOz(p-TOlyl) - C(CH3)2-OCONHPh -(CHZ)ECOZH --(CH2)&02H, Ba-salt H3C- C~C-CEC-CH~OH

mP

["CI

101 112

70-71 108-110

153

172 205

77-78 96

160 113 -

44

Reac- tivity&)

- + - -

++t

+ + + + + +

++ + + +

+ + + + + + -t

Polymeri- zation

temp. b)

["CI

- 80 - -

95

110 163 60 65

90 100

30

-

Color c)

- brown-red

- -

blue-violet

red-violet purple red purple blue red

blue black black red

-

a) - : no reactivity; + : yield < 1 %, + + : yield < 20%, + + + : > 20% after 5 hrs of UV-irradiation in suspension a t 25'C (200 W high-pressure Hg-lamp) or after 10 hrs of annealing-time below the mp (e.g. 14.21)).

c ) of the polymer crystals as polymerized. b) For best result in thermal polymerization.

39

G. WEGNER

It is this peculiar structure of the main chain which provides the chromophore responsible for the deep color and metallic brilliancy of polydiacetylenes and it is the parallJ arrangement of the polymer chains within the polymer crystals as the consequence of the solid-state reaction mechanism which is responsible for the dichroic behavior of the polymer single crystals. The all-trans configuration of the substituents is already predetermined by the packing of the molecules in the monomer lattice. It is worth noting tha t X-ray analysis confirmed that the planes of the phenyl rings of the substituents R in the case of the polymer from I are inclined at about 90” t o the fibre axis, a conclusion which was derived a t first from inspection of the polymerization behavior of diffirently substituted diacetylenes14). That is, replacement of the phenyl groups of hexadiindiol-bis-phenylurethanes by the u-naphthyl residue did not decrease the solid state reactivity (cf. Tab. 1). Because of the similar physical and chemical properties of all solid-state polymerized diacetylenes, the same general structure I11 or IV can be safely assumed for these substances.

111. Scope of the Reaction

It is essential for the understanding of the reaction mechanism of solid-state polymerizations t o investigate the influence of substituents onto the reactivity pattern.

As a rule, only those diacetylenes show solid-state reactivity which have substituents capable of forming hydrogen-bonds or possessing a high dipole moment. Substituents involving sulfonic acid esters, urethanes, amides, carboxylic acid groups or salts thereof are particularly useful GC t o engineer” highly reactive diacetylenes. Diacetylenes with pure aliphatic or aromatic substituents or having very voluminous side groups are usually not polymerizable. Tab. 1 gives a qualitative survey on the influence of various substituents onto the polymerizability of the conjugated triple bonds.

From inspection of these data it turns out tha t the influence of the substituents cannot be explained by mesomeric or inductive effects onto the single monomer molecule, but the influence of the substituents onto the structure of the lattice has t o be invoked. It seems tha t only those diacetylenes are reactive having substituents which favour an arrangement of the monomer molecules within their lattice by which the in- dividual molecules are arrayed in a ladder-like structure with the con-

40


jugated triple bonds forming the rungs and the substituents forming the side pieces of a ladder (e.g., by involvement of hydrogen bonds). With such an arrangement, a distance of about 3 A is achieved between in- dividual triple bonds of adjacent molecules. Polymerization takes place along these ladders by successive tilting of rungs or by cooperative shearing of the whole ladder. This mechanism is shown in Fig. 2 in a

A I I

I

j/+ I I

p I

I

I

R=le.g.l:

- H ~ C - O - S - N H ~ 0

Or:

- H z C - O - d m k $ Q b

Fig. 2. Scheme of the topochemical polymerization of diacetylenes; R stands for a polar substituent (c j . Table 1 or 2), the broken lines between substituents R indicate interactions

due to hydrogen-bonding or strong dipol-dipol-interaction

rather simplified manner. It can be visualized that the centre of gravity of the monomer molecules as well as the side groups R need not to be moved during the polymerization process, which is brought about by a shearing operation of the conjugated triple bonds. Therefore, the lattices of the monomer and of the polymer should be very similar or essentially isomorphous.

This model of a solid-state polymerization which we call “shearing polymerization” was essentially confirmed by X-ray analysis of the monomeric 2.4-hexadiin-1.6-dio117), diacetylenedicarboxylic acid17,18) and of the polymer of 116). Recent work by HASEGAWA et ~ 1 . 1 9 ) shows tha t the solid-state polymerization of p-phenylene-bis-acrylic acids mentioned above follows a very similar “shearing mechanism”.

41

G . WEGNER

It must, however, be pointed out tha t the polymer formed by a solid state reaction is forced to accept a crystalline lattice for kinetical reasons which may not correspond to the thermodynamically stable modification of the polymer under investigation. Therefore, relaxation processes can take place as the polymerization advances in the monomer crystals, thus destroying the original texture of the solid-state polymerized polymer. This is quite general for all solid-state polymerizations3) and is also observed in some cases with diacetylenes. I n these cases polymer single crystals like those from the highly reactive modification of 2.4-hexadiin-1.6-diol-bis-phenylurethzne cannot be obtained, but less ordered structures of the smectic or nematic type are formed. This is true for one other modification of lhe same monomer as well as for 2.4-hexadiindiol or for the bis-stearylurethane of this diol.

An even deeper insight into the scope and mechanism of the topochemical polymerization of diacetylenes can be gained by looking a t the polymerization behavior of sym. substituted diphenyldiacetylenes20) which is summarized in Tab. 2. As i t could be predicted, diphenyldiacetylene cannot be polymerized. A surprising effect is, however, that, if a class of compounds is reactive a t all, only the ortho- and meta-

Table 2. Solid-state reactivity of derivatives of diphenyldiacetylene as dependent on the nature and position of the substituents a t the phenyl rings, general structure :

R'-Ph- CKC- C=C-Ph-R'ZO)

Substituent R'

-H -NO2 -NO2 --NO2 -NH-COCHs -NH-COCH,q -NH-COCHz -NH-COPh - NH- COPh

-NHCONHPh -NH-COPh

-NHCONHPh -NHCONHPh

Posi- tion

-

0

m

P 0

m P

m P

0

0

in

P

mP

["CI

88 215 152 290 235 252

> 345 216 232 308 205 310

>345

no 2.0 3.5

no 19 25 no 0.2 3.0

no 4.0

15.0 no

Yield b)

no

no 36.5 (172'C, 24 hrs) 88.8 (12OoC, 48 hrs) no

no 16.5 (150°C, 70 hrs) 25.4 (14OoC, 51 Iirs) no

Colorc)

-

dark red dark red

red violet green-blue

violet violet

light blue green-blue

-

-

-

-

a) After one hr of UV-irradiation, conditions as given in Table 1. b) Thermal polymerization (annealing time, temp.). c) of the polymer crystals as polymerized.

42


disubstituted compounds are reactive, bu t the para-disubstituted iso- mer does not polymerize a t all. This fact is most clearly demonstrated within the serics of the diacetylaminodiphenyldiacetylenes. The or tho- and metadisubstituted compounds belong to the most reactive diacetylenes known to the author, whereas the p-disubstituted derivative does not react a t a l l even after prolonged UV-irradiation or annealing for many days.

A plausible explanation for the observed effects can be given by close inspection of the reaction scheme sketched in Fig. 2. It has to be con- sidered that shearing or successive tilting as i t is required by the proposed polymerization mechanism is possible in real molecules only by using the free rotation around single-bonds. The idea is easily understood by looking a t a simplified mechanical model of the reaction as it is shown in Fig. 3 A. It consists of a frame in which two rods “a” and two rods

I

I

/

a

A c -

/ / / b

/ / /

Fig. 3. Simplified mechanical model of the mechanism of motion of the polymerization of diacetylenes (A); B : spe- cial case of A, no shearing action is possible ; C : molecular model according to B, this compound does not show solid-state reactivity (see Table 2)

L‘”’ are connected by four rods “c” which become axes of rotation. Such a frame is easily deformed by pulling in the direction of the arrows thereby considerably shortening the distance between the two rods “a”. The angle between the axes of rotation “c” and the rods “a” may be changed freely without affecting the possibility of shearing the whole frame. However, there is one exception which is shown in Fig. 3B. A totally stiff frame is obtained and no shearing is possible a t all, if the

43

G. WEGNER

axes of rotation “c” are placed into the plane of the rods “a” which is the plane of shearing.

Two molecules connected by hydrogen-bonds t o form a stiff frame corresponding to the model B arc shown in Fig. 3 C. These two molecules are part of the ladder which could possibly be formed within the lattice of the p-disubstituted diacetylaminodiphenyldiacetylene. Here, the axes “c” are provided by the C-N-single-bonds between phenyl rings and amide side-groups, the two rods “b” are contributed by the N-H.-.O=C- bonds and the two rods “a” by the two conjugated triple bonds with a phenyl ring a t each side. A very stiff frame is obtained by putting to- gether models of molecules in the described manner which cannot be sheared. It is, therefore, plausible that this compound or similar disubstituted diphenyldiacetylenes do not show any solid-state reactivity. However, if the polar substituents at the phenyl rings are placed into the ortho-or neta-position relative to the conjugated triple-bonds, the axes of rotation, tha t is the C-N-bonds between phenyl rings and amide groups, are placed at an angle of 60” or 120”, respectively, to the plane of the triple bonds. This corresponds to the model shown in Fig. 3A. Therefore, shearing is possible and consequently ortho- and meta-disubstituted diphenyldiacetylenes with polar substituents exhibit solid- state reactivity.

It is worth mentioning tha t the mechanism of thermal and of radiation induced polymerization of diacetylenes may be quite different.21). The activation energy of the photoinduced polymerization of the bis-p- toluene sulfonic acid ester of 2.4-hexadiindiol (11, Eq. (2) (A < 300 mp)) was determined to be ca. 3 kcal/mole. The thermal polymerization of the bis-phenyl-, bis-naphthyl- and bis-p-tolyl urethanes of 2.4-hexadiin-1.6-

1/T. lo3( O K - ’ )

Fig. 4. ARRRENIUS plots for the thermal polymerization of three differently substituted urethanes of 2.4-hexadiin-1.6-diol. General formula : R-C=C-CrC-R

o R = CH2-O-CO-NH-a-naphthy1, 0 H = CHz-0-CO-NH-p-tolyl, R = CH2-0-CO-NH-Ph; Ea = 19 kcal/mole

44


diol in the dark showed an activation energy of 19 kcal/mole being in- dependent of the substituents. This value was derived from the ARRHE- NIUS plot of the slopes of the original time-conversion curves (Fig. 4).

IV. Polymer Properties

The interesting property of the polymeric diacetylenes t o form single- crystals exhibiting strong dichroism has already been mentioned. As a rule, the direction of main-absorption is that of the morphologically longest axis of the crystals which coincides with the fibre axis. The polymer crystals possess semiconducting properties which are now under investigation in our laboratory. Preliminary results are summarized in Tab. 3. The absolute values of conductivity are rather low but obviously depend on the type of substituents. The activation energy of the dark- conductivity was found t o be within the limits expected for polyenes22). The polymers show also photo-conductivity.

Table 3. Preliminary results for the electric dark-conductivity of polymer crystals from solid-state polymerization of diacetylenes25)

/R /c=c=c=c \

... \

... General structure :

R

Substituent R

H

- CH2-0- CONH-< 3- CH3

-CH~-O-CONH-< -)

2.10-10

3.4.10-11

2.8.10-12

4.4 . l o 4 3

8.10-11

EA [el’].)

0.84

0.8

0.78

0.99

0.92

8) Measured from polycrystalline samples and calculated according to (I = 00 exp (-&/LkT)

Almost all polymers are soluble in hexamethylphosphoricacid tris- amide (HMPA) or mixtures of this solvent with lithiumchloride and form highly viscous deep orange t o violet solutions. rj8p/c-values as high as 2.0 (l./g) in the case of thermal polymerization of I (Eq. 2) or 0.25 (l./g) in the case of I1 (Eq. (2)) can easily be obtained. These data were obtained with a polymer concentration of 1.0 (g/l.) in HMPA containing 5 % of lithium chloride a t 25°C. On addition of basic reagents like tertiary

45

G. WEGNEXI

R: ...- C y - O - ~ - N H ( C H ~ ~ - N H - ~ - C H ~ . . - 0 0

amines t o these solutions, the polymers depolymerize rapidly. Decom- position clso takes place by heating these polymers a t temperatures above 200 "C ; no melting could be observed so far.

h *V OR AT ELEVATED TEMPERATURE

V. Solid-state Reactivity of Polymers Involving Conjugated Triple Bonds

It seemed interesting t o prove whether the solid-state rxictivity of monomers with conjugated triple bonds can be found also with polymers having conjugated triple bonds in the base unit. Such polymers could be synthesized easily23). The polyurethanes obtained from 2.4- hexadiin-1.6-diol (V) or 3.6.13.16-tetraoxaoctadeca-8.10-diin-1.18-dio1 (VI) and hexamethylme diisocyanate as well as the polyester from V and adipoylchloride quite rapidly develop a deep red color on exposure t o UV-light or on annealing a t elevated temperatures below their melting points. During this process the polymers become insoluble. Another method to prepare polymers with conjugated triple bonds in the base- unit by oxidative coupling of acetylenes was reported by HAY and his coworkers24). These polymers also show very similar solid-state reactivity.

H 0 f CH2- CH, - W H , - C S C - C S C - CH, f 0 - CH, - CH,+O - H

VI

The solid-state reaction is catalyzed by radical initiators and is in- hibited by radical scavengers. Solutions of these polymers in various

Fig. 5. Scheme of the topochemical crosslinking reaction of polymers containing two conjugated triple bonds per repeating unit

46


solvents do not show any reactivity when exposed to light or heat. The reaction leading to discoloration and crosslinking can be rationalized in analogous manner to that of low-molecular weight diacetylenes with similar structure (compare Fig. 5). I t is a solid-state-reaction taking place within the crystalline regions of the polymers. It involves the conjugated triple bonds which are transformed by a 1.4-addition reaction into three cumulated double bonds.

The work reviewed in this paper was supported by the DEUTSCHE FORSCHUNGSGEMEINSCHAFT and by the BASF AG, Ludwigshafen (X-ray structure analysis). The author gratefully acknowledges the help of Dr. E. HXDICKE (Ludwigshafen) and Dip1.-Phys. I. KAISER (Mainz) in X-ray work and gives his thanks to Prof. E. W. FISCHER (Mainz) and Prof. C. H. KRAUCH (Ludwigshafen) for many helpful discussions and suggestions. He also thanks Prof. W. KERN (Mainz) for his pertinent interest in this work.

1 ) H. MORAWETZ, J. Polymer Sci. Part C 12 (1966) 79. 2 ) B. WUNDERLICR, Angew. Cliem. 80 (1968) 1007. 3) G. WEGNER, A. MUNOZ-ESCALONA, and E. W. FISCRER, I3er. Bunsenges. Physik. Chem.

4) M. HASEGAWA, F. SUZUKI, H. NAKANISIII, and Y. SUZUKI, J. Polymer Sci. Part B 6

6) M. HASEGAWA, Chem. High Polymers [Tokyo] [Kobunshi Kagaku] 27 (1970) 337. 6 ) G. M. J. SCHMIDT, Photochemistry of the Solid-state, in : Reactivity of the Photo-

7) A. BAEYER and L. LANDSBERG, Ber. Deut. Chem. Ges. 15 (1882) 61. 8 ) K. BOWDEN, J. HEILBRON, E. R. H. JONES, and K. H. SARGENT, J. Chem. SOC. 1947,

9 ) J. B. ARMITAGE, C. L. COOK, N. ENTWISTLE, E. R. H. JONES, and M. C. WHITING, J.

74 (1970) 909.

(1968) 293.

exited Organic Molecule, Wiley, New York 1967.

1582.

Chem. SOC. 1952, 1998. lo) F. BOHLMANN, Angew. Chem. 69 (1957) 82. 11) F. STFIAUS, L. KOLLEK, and W. HEYN, Ber. Deut. Chem. Ges. 63 (1930) 1868; F. STRAUS,

12) A. SEEER, Liebigs Ann. Cliem. 589 (1954) 222. 13) Y. TABATA, in: Advances in Macromolecular Chemistry, Academic Press, London 1968,

14) G. WEGNER, Z. Naturforsch. b 24 (1969) 824.

L. KOLLEK, and H. HAUPTMANN, ibid. 63 (1930) 1886.

Vol. 1, p. 297.

47

G. WEGNER

15) A. I. KITAIGORODSKII, Organic Chemical Crystallography, Consultants Bureau, New

16) E. H ~ I C K E , E. C. MEZ, C. H. KRAUCH, G. WEGNER, and I. KAISER, Angew. Chem.

17) E. HADICKE, K. PENZIEN, and W. SCHNELL, Angew. Chem. 83 (1971) 1024. 18) J. D. DUNITZ and J. M. ROBERTSON, J. Chcm. SOC. 1947, 1145. 19) M. HASEGAWA, private Communication. 20) G. WEGNER, J. Polymer Sci. Part B 9 (1971) 133. 21) G. WEGNER, Makromol. Chem. 145 (1971) 85. 22) Y. OKABIOTO and W. BRENNER, Organic Semiconductors, Reinhold Publ., New York

23) G. WEGNER, Makromol. Chem. 134 (1970) 219. 24) A. S. HAY, D. A. BOLON, K. R. LEIMER, and R. F. CLARK, J. Polymer Sci. Part B 8

25) W. SC~ERMANN and G. WEGNER, unpublished results.

York 1961.

83 (1971) 253.

1964.

(1970) 97.

48

topochemical polymerization of monomers with conjugated triple bonds

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