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Progress in Organic Coatings 64 (2009) 124–127

Contents lists available at ScienceDirect

Progress in Organic Coatings

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ynthesis of organic–inorganic polymer hybrids from poly(vinyl chloride)nd polyhedral oligomeric silsesquioxane via CH/� interaction

akeru Iwamuraa, Kaoru Adachib, Masato Sakaguchia, Yoshiki Chujob,∗

Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, JapanDepartment of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan

r t i c l e i n f o

rticle history:eceived 24 June 2008eceived in revised form 15 August 2008ccepted 18 August 2008

a b s t r a c t

The synthesis of poly(vinyl chloride) (PVC)/polyhedral oligomeric silsesquioxane (POSS) polymer hybridswas performed utilizing CH/� interaction. Poly(vinyl chloride) as an organic component was dissolvedin THF with octaphenethylsilsesquioxane (Phenethyl-POSS) or octacyclohexylsilsesquioxane (Cyclohexyl-POSS) as an inorganic component. The resulting mixture was placed at 40 ◦C for 2 weeks. The obtained

eywords:olymer hybridoly(vinyl chloride)olyhedral oligomeric silsesquioxane

polymer hybrid was dried in vacuo at 60 ◦C for 2 days. The transparent polymer hybrids were obtainedwhen Phenethyl-POSS was employed as an inorganic component. In contrast, polymer hybrid becameturbid when Cyclohexyl-POSS was used. These results suggest that the CH/� interaction was found to actas an important role for the dispersion of Phenethyl-POSS in the PVC matrix.

© 2008 Elsevier B.V. All rights reserved.

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. Introduction

Synthesis of organic–inorganic polymer hybrid material hasttracted much attention as a preparation method for new charac-eristic materials. Especially, the organic–inorganic hybridizationan be used for the preparation of composite materials ofrganic–inorganic materials. Moreover, the properties of organicr inorganic materials are reflected in the obtained materials. Untilow, a sol–gel reaction has been employed as a general methodo obtain the organic–inorganic polymer hybrids [1]. However, its not necessary to use a sol–gel reaction for the preparation ofrganic–inorganic polymer hybrids.

In recent years, the polyhedral oligomeric silsesquioxanePOSS) has been attracting a great deal of attention [2].he term silsesquioxane is the general name for organosil-cate species with the empirical formulas (RSiO1.5)n (R = H,ydrocarbon) and closely related compounds. The structuresf silsesquioxanes have been known as irregular, ladder, cage,nd partial cage structures [3]. Since the caged part of

ilsesquioxane has similar structure to silica gel, these com-ounds can be regarded as an inorganic compound. We haveeveloped the synthesis of organic–inorganic polymer hybridsased on silsesquioxanes [4]. However, we have not sufficiently

∗ Corresponding author. Tel.: +81 75 383 2604; fax: +81 75 383 2605.E-mail address: chujo@chujo.synchem.kyoto-u.ac.jp (Y. Chujo).

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300-9440/$ – see front matter © 2008 Elsevier B.V. All rights reserved.oi:10.1016/j.porgcoat.2008.08.035

ried utilization of a silsesquioxane as an inorganic compo-ent.

We have recently investigated organic–inorganic polymerybrids utilizing the weak intermolecular interactions such as–� interation [5] and CH/� interaction [6]. In these studies,e succeeded in the preparation of organic–inorganic poly-er hybrids by using the weak intermolecular interactions

etween the organic polymer and the sol–gel matrix. For exam-le, organic–inorganic polymer hybrids were prepared utilizinghe CH/� interactions between the CH groups of poly(vinyl chlo-ide) (PVC) and the phenyl groups of sol–gel matrix which waserived from phenyltrimethoxysilane [6]. Therefore, we expect thatrganic–inorganic polymer hybrids can be prepared by using theeak intermolecular interactions between the organic polymer

nd the organic functional groups introduced into the cage-likeilsesquioxanes. In this article, we report on the results of the syn-hesis of organic–inorganic polymer hybrids from PVC and cage-likeilsesquioxanes via CH/� interaction (Scheme 1).

. Experimental

.1. Materials

Poly(vinyl chloride) (DP = 1100) was purchased from Wako Purehemical Industries, Ltd. PVC was purified by reprecipitation from

ts THF solution into methanol and dried in vacuo. Octaphenethyl-ilsesquioxane (cage mixture, n = 8, 10, 12) (Phenethyl-POSS) and

T. Iwamura et al. / Progress in Organic Coatings 64 (2009) 124–127 125

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noTiaorsstoCsthesis of homogeneous polymer hybrids of polymers having activeCH groups and the aromatic rings of POSS.

The FT-IR spectra of PVC/Phenethyl-POSS and PVC/Cyclohexyl-POSS are shown in Fig. 3. The IR spectrum of PVC showed the

Scheme 1. Synthesi

ctacyclohexylsilsesquioxane (Cyclohexyl-POSS) were purchasedrom Sigma–Aldrich Co. Tetrahydrofuran (THF) was dried overodium and distilled under nitrogen atmosphere. The other sol-ents and reagents were used as supplied.

.2. Measurements

Scanning electron microscopy (SEM) measurements were con-ucted using a JEOL JSM-5600B system. The FT-IR spectra werebtained on a PerkinElmer 1600 infrared spectrometer. Thermo-ravimetric analysis (TGA) was performed using a TG/DTA6200,EIKO Instruments, Inc., with heating rate of 10 ◦C/min in air.ynamic mechanical analysis (DMA) was conducted on a DMS 210

SEIKO Instruments, Inc.). The sample was measured at 1 Hz. Theemperature for the measurement was raised from 20 to 180 ◦C athe rate of 2 ◦C/min.

.3. Synthesis of organic–inorganic polymer hybrids from PVCnd silsesquioxane (typical procedure)

PVC (0.50 g) was dissolved in 20 mL of THF with the pre-cribed amounts of Phenethyl-POSS (0.25 g, Table 1, Run 1),yclohexyl-POSS (0.25 g, Table 1, Run 2). After being stirred at roomemperature for 1 h, the mixture was placed in a polypropylene ves-el covered with a wiping paper and left in air at 40 ◦C for 2 weeks.he obtained polymer hybrid was dried in vacuo at 60 ◦C for 2 days.

. Results and discussion

The effect of the organic functional groups introduced to theilsesquioxanes on the homogeneity of polymer hybrid was firstnvestigated. PVC as an organic component was dissolved in THF

ith Phenethyl-POSS or Cyclohexyl-POSS as an inorganic compo-

able 1ynthesis of PVC and R8-POSS polymer hybrids.

un PVC (g) R8-POSS Appearance

R- (g)

0.501 Phenethyl 0.247 Transparent0.499 Cyclohexyl 0.253 Turbid

FP

C/R8-POSS hybrid.

ent. The resulting mixture was placed at 40 ◦C for 2 weeks. Thebtained polymer hybrid was dried in vacuo at 60 ◦C for 2 days.he results are summarized in Table 1. Only in the system employ-ng Phenethyl-POSS, the transparent polymer hybrid was obtainedfter removal of the solvent (Fig. 1). The PVC/Phenethyl-POSS hybridbtained had good film forming property. The dispersion in theesulting polymer hybrid was also examined by SEM. When theample was prepared from Phenethyl-POSS having aromatic rings,ilica domains could not be found in a micron order. Fig. 2a showsransparent polymer hybrid prepared from Phenethyl-POSS. On thether hand, the samples prepared from non-aromatic POSS such asyclohexyl-POSS showed phase separation (Fig. 2b). These resultsuggest that the CH/� interactions are quite effective for the syn-

ig. 1. Appearance of PVC/Phenethyl-POSS hybrid (Table 1, Run 1) andVC/Cyclohexyl-POSS composite (Table 1, Run 2).

126 T. Iwamura et al. / Progress in Organic Coatings 64 (2009) 124–127

Fig. 2. SEM images of (a) PVC/Phenethyl-POSS hybrid (Table 1, Run 1) and (b) PVC/Cyclohexyl-POSS composite (Table 1, Run 2).

-POSS

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Fig. 3. IR spectra of PVC, Phenethyl

bsorption band at 2975 cm−1 based on the CH stretching fre-uency. In the IR spectrum of PVC/Phenethyl-POSS hybrid, thisbsorption band was observed at 2972 cm−1. Additionally, the

romatic CH stretching absorption bands at 3106 and 3063 cm−1

ere shifted to lower frequency after hybridization (3105 and062 cm−1). This result might indicate an existence of CH/� inter-ction between methine proton adjacent to the chlorine atom andhenethyl group adjacent to the silicon atom. In the case of the

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Fig. 4. DMA results of PVC/Phenethyl-POSS hybrid: (a) profiles of tan ı

, and PVC/Phenethyl-POSS hybrid.

ransparent hybrid prepared from PVC and Phenethyl-POSS, theH stretching absorption band was shifted to lower frequency afterybridization.

The dynamic visco-elasticity of the polymer hybrids was inves-igated using dynamic mechanical analysis to evaluate the effectf Phenethyl-POSS content. The results of DMA for the polymerybrids are shown in Fig. 4. With an increase in Phenethyl-POSSontent, the peak temperature of tan ı and the value of E′ were

versus R8-POSS (wt%) and (b) profiles of E′ versus R8-POSS (wt%).

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ecreased. These results suggest that the hybridization of PVC andhenethyl-POSS may contribute in weakening the intermolecularnteraction of PVC. As a result, the glass transition temperaturend Young’s modulus of the obtained polymer hybrids might beecreased.

. Conclusions

The hybrid of PVC and polyhedral oligomeric silsesquioxaneaving phenethyl groups was prepared by utilizing the CH/� inter-ctions between the CH groups of the organic polymer and thehenethyl groups of POSS. The results show the possibility of thereparation of the hybrid materials without chemical bonds. Usagef the CH/� interactions may have some advantages in prepara-ion process. It can be incorporated into preformed organic polymerithout modification of the polymers. From the viewpoint of the

ybrid preparation, many kinds of hydrophobic polymers are appli-able to hybridization by using CH/� interaction.

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