JOURNAL OF POLYMER SCIENCE VOL. 61, ISSUE 171 (1962)

NOTES Preparation and Intra-Intermolecular Polymerization of

S,S'-Diviny lmercaptals

In connection with our investigations concerning the intra-intermolecular polymer- ization of S,S'-divinyldithiolcarbonate,l we have also studied the polymerization of S,S'-divinylmercaptals. A recent note by Maboyan and Saakyanz concerning the synthesis of analogous compounds prompts us to report the preparation and polymeriza- tion of formaldehyde-S,S'-divinylmercaptal (formula 111, where R = -H) :

KOH (HO-CHz-CHz4)zCH-R CHz

200-250" (1) \+CH?CH %H

(111) tert-butanol / I I

( Cl-CHz-CHz-S)zCH-R S

\CH? (11) KO-C(CHa)a

I R

I

R

We have found that the unsaturated mercaptalv (111) can be prepared either by dehydro- halogenation of the p-chloroethylmercaptals (I) or by dehydration of the p-hydroxy- ethylmercaptals (11). The latter method is recommended since it affords better yields (30-40%) and does not require the use of chloroethylmercaptals, which are strong vesi- cants. Formaldehyde-S,S'-divinylmercaptal (111, R = -H), b.p. 105-107" at 120 mm. Hg:

the infrared spectrum of the monomer showed absorption maxima for CHFCH- at, 1592 and 870 em.-'. The vinyl absorption at 1592 cm.-' is the strongest absorption in the spectrum.

ANAL. Calcd. for C5H&: C 45.41, H 6.10, S 48.49. Found: C 45.45, H 6.25, S 48.62.

The monomer wm polymerized with azobisisobutyronitrile rn initiator. Either solu- ble and linear or insoluble and crosslinked polymers could be obtained, depending on the polymerization conditions. Polymerization in solution and low conversion favored the formation of linear polydivinylmercaptal. The polymers are soluble in chloroform, benzene, and tetrahydrofuran, and their infrared spectra show only weak absorption in the vinyl region. These findings are in agreement with the proposed structure IV con- taining cyclic units in the main chain.

ANAL. Calcd. for (CJ&S& (IV, R = -H): C 45.41, H 6.10, S 48.49. Found: C 45.14, H 6.00, S 48.72.

s11

S12 JOURNAL OF POLYMER SCIENCE, VOL. 61, ISSUE 171 (1962)

Further polymerization and copolymerization studies of S,S '-divinylmercaptals are currently under way and will be reported in detail a t a later date.

This research wzts supported by the Department of the Army, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D.C., under Contract PA-49-113-MD-2032. Grateful acknowledgment is also made to Mr. Thomas Reilly for his help in the synthesis of the 8-chloroethylmercaptals.

References

1. Ringsdorf, H., and C. G. Overberger, Makromol. Chem., 44/46,418 (1961). 2. Matsoyan, S. G., and A. A. Saakyan, Vysolcomolekulyarnye Soedinaiya, 3, 1754

(1961).

HELMUT RINGSDORF C. G . OVERBERGER

Department of Chemistry Polytechnic Institute of Brooklyn Brooklyn, New York

Received March 2, 1962

High Resolution NMR Spectra of Polyvinyl Chloride, Polyvinylidene Chloride and Vinyl Chloride-Vinylidene Chloride Copolymer

The proton magnetic resonance of solutions of polyvinyl chloride (PVC), polyvinyli- dene chloride (PVDC) , and vinyl chloride-vinylidene chloride copolymer in o-dichloro- benzene was measured on a Varian Associates High Resolution Spectrometer (Model V-4311) operating at 60 Mc. and equipped with a Variable Temperature NMR Probe Accessory (Model V-4340). The experiments were done at high temperature (about 100OC.) to get the good solubility of the polymers and to attain a better resolution of the spectra. The dissolved sample (10% concentration) was sealed into a capillary tube under an atmosphere of nitrogen gas to avoid oxidative degradation during the course of experiment.

The obtained spectra of the methylenic protons of the three kinds of polymers are re- produced in Figure 1, (a) and (b). We have attempted to study the local regularity of the polymers by analyzing the spectra. The methylenic protons in the segment,s of syn- diotactic configuration are expected to give a triplet structure. The appropriate en- velope of a triplet structure (dotted curve, Figure la) was constructed and employed as the basis for calculation of the syndiotactic and isotactic contents ( N , and N J of the PVC molecule. The average chain length in number, (s) and (i), of monomer unit.s for both types of stereospecificity and the energy difference, J , between syndiotactic and iso- tactic chain propagation during the polymerization process were calculated with the aid of the theory' developed by one of the authors (Table I).

TABLE I Local Regularity of PVC

~~ ~

1 64 36 2 .8 1 .6 -0.59 2 44 56 1 . 8 2.3 0.24 3 65 35 2 . 9 1 . 5 -0.62