5-7 OCTOBER

ISFR

2011

115

TOLEDO (SPAIN)

CARBONATE CATALYZED NUCLEOPHILIC SUBSTITUTION OF POLY(VINYLCHLORIDE)
G. Grause, T. Hosoya, T. Kameda, T. Yoshioka
Graduate School of Environmental Studies, Tohoku University, Aramaki Aza Aoba 6-6-11, Aoba-ku Sendai 980-8579, Japane-mail: grause@env.che.tohoku.ac.jp

AbstractPoly(vinyl chloride) was modified by the nucleophilic substitution with iminodiacetic acid dimethylester and n-decathiol.
The reaction took place in dimethylformamide and cyclohexanone with K 2CO3 as a catalyst. Under the conditions used,the direct substitution with iminodiacetic acid was not successful; however, the acid might be accessible by the hydrolysisof the ester. The modification changed properties of the original polymer. It is expected that the iminodiacetic acidmodified PVC can be used as a cationic ion exchanger. n-Decathiol modified PVC might have the properties of flexible
PVC.

Keywords: Iminodiacetic acid; Iminodiacetic acid dimethylester; n-decathiol; PVC modification

1. Introduction

2. Materials and Methods

Modification of waste poly(vinyl chloride) (PVC) is one
possibility for the utilization of waste plastics.
Nucleophilic substitution is applicable to rigid and flexible
PVC, as well [1, 2]. Various groups can be introduced
into the polymer. Especially amines and thiols have
proven to be appropriate nucleophiles. The substitutionof chlorine by isothiocyanate resulted in an antibacterial
active material [3]. In this work it was tried to introduce
another two groups, iminodiacetic acid and n-decathiol,
into the polymer matrix (Fig. 1).
Iminodiacetic acid is well known as a chelater. It might bepossible to convert used PVC into a polymer with cationic
ion exchange properties, if iminodiacetic acid isintroduced.
The introduction of long-chain aliphatic thioether groups
into the polymer matrix would weaken the interaction
between polymer chains. Therefore, it can act as aplasticizer for a new kind of flexible PVC without the riskof releasing monomeric plasticizer molecules.

Plain PVC powder was used in order to avoid effects
from foreign materials. K2CO3 was also provided from
Wako Chemicals. Solvents, iminodiacetic acid, andn-decathiol were delivered from Kanto Chemicals.
Iminodiacetic acid dimethylester was prepared by theesterfication of iminodiacetic acid with methanol. Thesodium salt of iminodiacetic acid dimethylester wasobtained by the reaction of sodium hydride with thedimethylester. Water was removed from all the chemicals
used in order to avoid the introduction of hydroxyl-groups
into the modified PVC.

a)

ClClClR

RNClClHSRClRNClClR

R

Cl-HClCOOHCOOHCOOHCOOHb)

The modification of PVC was carried out in a three neckflask at 100 °C in dimethyl formamide andcyclohexanone, respectively. 1.0 g of PVC was dissolvedin 50 ml solvent and 16 mmol of nucleophile and 1.11 gof K2CO3 was added as a catalyst. After a reaction timeof 4 h, the product was precipitated by the addition of amethanol/water mixture, filtrated, and dried.

-HClRClRS

Fig. 1. Nucleophilic substitution of PVC with a) iminodiacetic acid and b) n-decathiol.

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6th International Symposium on Feedstock Recycling of Polymeric Materials

180 160 140 120 100 80 60 40 200ppm

Fig. 2. 13C-NMR of iminodiacetic acid dimethylester
modified PVC
Substitution and elimination yield were calculated from
1H-NMR data.

3. Results and Discussion
The nucleophile substitution of PVC with iminodiaceticacid, iminodiacetic acid dimethylester, and theiminodiacetic acid dimethylester sodium salt was carriedout in dimethyl formamide. 13C-NMR (Fig. 2) showed thesuccessful introduction of the dimethylester in thepolymer, while the acid did not show any reactivity (Table1), probably due to the reduced nucleophilicity by themesomeric effect of two neighboring acetyl-groups. Theeffect of sodium salt was weaker as that of the K 2CO3
catalyzed reaction. The elimination of about 10% of thechlorine during the reaction with iminodiacetic acid wasprobably the result of the addition of K2CO3 as a catalyst
and not caused by the nucleophile.
n-Decathioether groups were successfully introduced into
the PVC polymer using cyclohexanone as a solvent.
From the 1H-NMR (Fig. 3), it can be seen that about
2.5% of the chlorine was substituted by n-decathiol(Table 1). Another 9% of the chlorine was eliminated.
Since no change in the color was observed, it can beassumed that the length of cumulated double bonds waslimited.
The introduction of n-decathioether groups had anoticeable effect on some properties of the material.

Fig. 3. 1H-NMR of n-decathiol modified PVC
Compared with the original PVC sample, the solubility ofthe modified PVC was significantly improved in somesolvents such as chloroform.

4. Conclusions
The modification of PVC with iminodiacetic acid
dimethylester and n-decathiol results in a polymer withdifferent properties compared with the original polymer.
Even if iminodiacetic acid cannot be introduced directly,
the acid modified polymer is accessible by the hydrolysisof the ester, in order to make use of its capacity as achelating agent.
The modification of PVC with n-decathiol caused alsochanges in the properties of the original material.

References[1] T. Kameda, Y. Fukuda, G. Grause, and T. Yoshioka.
Chemical modification of rigid poly(vinyl chloride) by thesubstitution with nucleophiles, J. Appl. Polym. Sci. 116(2010) 36-44.
[2] T. Kameda, Y. Fukuda, G. Grause, and T. Yoshioka.
Chemical modification of flexible and rigid poly(vinylchloride) by nucleophilic substitution with thiocyanate
using a phase-transfer catalyst, Mater. Chem. Phys. 124(2010) 163-167.
[3] T. Kameda, M. Ono, G. Grause, T. Mizoguchi, and T.
Yoshioka. Antibacterial effect of thiocyanate substitutedpoly(vinyl chloride), Journal of Polymer Research (2010)
1-3.

Table 1. Substitution and elimination yield of various nucleophiles.
Nucleophile
Iminodiacetic acid
Iminodiacetic acid methyl ester
Imonodiacetic acid dimethyl ester sodium salt
n-Decathiol

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Substitution [%]3.6
2.8
2.5Elimination [%]1029368.8

Solvent
Dimethyl formamide
Dimethyl formamide
Dimethyl formamide
Cyclohexanone

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