MODIFICATION OF PVC WITH LONG ALKYL CHAINSBY NUCLEOPHILIC SUBSTITUTION
Y. Nagasaki, K. Hashimoto, G. Grase, T. Kameda, T. Yoshioka*
Graduate School of Environmental Studies, Tohoku University
e-mail: yoshioka@env.che.tohoku.ac.jp
TEL/FAX: +81-22-795-7212

Abstract
We investigated modifying poly(vinyl chloride) (PVC) by with long alkyl chains by nucleophilic substitution with layered
double hydroxides(LDH) as basic catalysts. The degrees of substitution and elimination were analyzed by 1H-NMR. PVC
reacted not only with thiols and alcohols, but also with amines and calboxylic acids. Derivatives of thioglycolic acidreacted with PVC in a high degree of substitution. In cyclohexanone, reactivity was very low, but substitution selectivity
was extremely high. On the other hand, in N,N-dimethylacetamide (DMAc), reactivity was higher than cyclohexanone but
elimination reaction also occurred. Thermal stabilities of the modified PVC were analyzed by TG/DTA. LDH intercalatedwith various anions (CO32-, OH-, NO3-) was used, and the LDH intercalated carbonate displayed the highest reactivity.
LDH made by various hydroxides was used, and while Mg-Al and Li-Al LDH worked as catalysts, the reaction was notobserved with Cu-Al or Zn-Al LDH.
Keywords: Poly(vinyl chloride), Nucleophilic substitution, Layered double hydroxides

1. Introduction
Poly(vinyl chloride) (PVC) is a plastic that has many
exceptional properties like thermal resistance, durability
and workability. Therefore, it is used for pipes, cables,
medical use bags, etc. Some waste PVC is recycled, but
seriously degraded PVC and composite materials arelandfilled because recycling is difficult. To promoteresources recycling, a new way of recycling is necessary.
One option is upgrade recycling. It is a way of recyclingthat consists in dechlorinating PVC and introducing otherfunctional groups by substitution reaction [1]. We
achieved addition of antibacterial properties to PVC bynucleophilic substitution in an earlier paper [2]. New
functions added to PVC differ depending on thenucleophile. If nucleophiles with long alkyl chains areadded, an increase of plasticity is expected. In thisreaction, a base is needed to cause substitution.
However, not only substitution but also elimination occurs
by the base. To restrain elimination, we used layered
double hydroxides (LDH) as basic catalysts. LDH
consists of positively charged brucite-like layers [Mg1-xAlx(OH)2]x+ alternating with disordered, negatively charged
interlayers [Ax/nn- ・ mHzO]x-. Since the basic anion istrapped within the interlayers, PVC polymer can not be incontact with the anion. In this study, we investigatedmodifying PVC with long alkyl chains by nucleophilic
substitution with LDH as basic catalysts from astandpoint of upgrade recycling.

2. Materials and Methods
2.1. Materials
Plain PVC powder was used in order to avoid effects
from foreign materials. Solvent and nucleophile were also

provided from Kanto Chemicals. LDH was prepared bycoprecitation method.
2.2. Methods
PVC (0.5 g, 8 mmol) and nucleophile were dissolved in
50 ml of solvent. LDH was added and the reaction
started under N2 atmosphere at 80 °C. After reaction,
LDH was removed by filtration. The mixture wasprecipitated in methanol or hexane. The modified
polymer was purified using THF/hexane as a solventprecipitant system. The modified PVC was analyzed by
1H-NMR, FT-IR, and TG/DTA. The LDH was analyzed by
XRD.

3. Results and Discussion
3.1. The effect of the nucleophiles
The degree of substitution and elimination of PVC
modified with various nucleophiles are summarized inTable 1. Without LDH, the reaction was not observed.
This result indicates that LDH acts as a catalyst in thisreaction. In cyclohexanone reactivity was very low, but
substitution selectivity was extremely high. On the otherhand, in N,N-dimethylacetamide (DMAc), reactivity was
higher than in cyclohexanone but elimination reaction
also occurred. No effects from the chain length of thealkyl thiols were observed. In the case of using
derivatives of thioglycolic acid, the degree of substitution
improved. The reason for that is that the carbonyl groupin the beta-position withdrew electrons and stabilized thethiolate anion. PVC reacted not only with thiols andalcohols, but also with amines and calboxylic acids.

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013Table 1. The degree of substitution and elimination of PVC modified with various nucleophiles.
Nucleophile
Solvent
LDH
Substitution (%)
Elimination (%)
1.6n.d.
○Cyclohexanone
n.d.
n.d.
×
1-Dodecanethiol
○
6.6
4.2
DMAc
n.d.
n.d.
×
Cyclohexanone
1.6n.d.
○1-Octanethiol
DMAc
5.0
6.5
○
Cyclohexanone
2.1n.d.
○1-Hexadecanethiol
DMAc
3.0
7.1
○
Cyclohexanone
2.3
n.d.
○
Isooctyl thioglycolate
DMAc
○
17.8
3.9
Stearyl thioglycolate
DMAc
○
12.8
4.4
1-Dodecanol
DMAc2.0n.d.
○Dodecylamine
DMAc
5.8
6.8
○
Tridecanoic acid
DMAc
2.4
7.1
○
3.2. Analysis of the pyrolysis substituted PVCIn Fig. 1, the TGA/DTA of pure PVC and PVC modified
with various nucleophiles are compared. The pyrolysis
behavior of the substituted PVC with 1-dodecanethiol
and isooctyl thioglycolate was almost the same as forpure PVC. However the tempereture of the start ofdechlorination (TD-onset) fell as substitution and elimination
reactions were promoted. Cl- groups decreased bysubstitution and elimination during the PVC modification,
causing a lower degradation temperature. In the case ofPVC substituted with 1-dodecylamine, dechlorination
temperature decreased greatly. It is assumed that theelimination of the amino group took place first, and thenthe eliminated amine attacked PVC. As a result,dechlorination reaction was promoted.

The LDH intercalated with carbonate showed the highest
reactivity. Therefore, it was observed that intercalatedanions played an important role in the reactivity.
3.4. The effect of the hydroxides in LDH
The degree of substitution and elimination of PVC
reacted with LDH made by various hydroxides are
summarized in Table 3. Mg-Al and Li-Mg LDH worked as
catalysts, but the reaction was not observed with Cu-Alor Zn-Al LDH. It depended on the solubility product (Ksp)of carbonate. The small solubility product (Ksp) ofcarbonate indicates that bonding strength between metal
ion and carbonate is strong and therefore, the reactivityof carbonate is small.
Table 3. The degree of substitution and elimination of
PVC reacted with LDH made by various hydroxides.
(Solvent: DMAc, Nucleophile: 1-Dodecanthiol)
LDH typeSubstitution(%)
Elimination(%)
Mg-Al
6.6
4.2
Li-Al
14.2
8.9
Cu-Al
n.d.
n.d.
Zn-Al
n.d.
n.d.

4. Conclusions
Fig.1 TG/DTA of modified PVC.
(S: substitution, E: elimination)
3.3. The effect of the anions intercalated in LDH
The degree of substitution and elimination of PVC
reacted with LDH intercalated various anions aresummarized in Table 2.
Table 2. The degree of substitution and elimination ofPVC reacted with LDH intercalated various anions.
(Solvent: DMAc, Nucleophile: 1-Dodecanthiol)
LDH type
Substitution(%)
Elimination(%)
LDH- CO3
6.6
4.2
LDH- OH
4.0
4.5
LDH- NO3n.d.
n.d.

PVC modified with nucleophiles with long alkyl chains
was obtained by nucleophilic substitution. In the case ofusing derivatives of thioglycolic acid, the degree ofsubstitution improved. Additionally, the modification of
PVC caused a lower degradation temperature. Lastly, itwas observed that the intercalated anions andhydroxides played an important role in the reactivity.

References[1] T. Kameda, M. Ono, G. Grause, T. Mizoguchi, T.
Yoshioka Journal of Polymer Research., 18, (2011) 945947[2] M. Yoshihara, G. Grause, T. Kameda, T. Yoshioka
Journal of Material Cycles and Waste Management, 12,(2010) 264-270

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013