j app polym sci 43 1605-1607 1991 lárez perdomo

8/3/2019 J App Polym Sci 43 1605-1607 1991 Lrez Perdomo

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Unsaturated olyesters. ll. Polyester rom Maleic Anhydrideand 1,4-Butylene lycol

CRSTOBAI . I-AREZ . and GILBERTO . PERDOMO MENDOZA'Univers idad e LosAndes , acul tad e Cienc . ias , e rar tamento e Quinr i r.a , a Hec:hicera , er ida 101,Venezuela

SYNOPSIS

Th e polyesterification reaction of malei c anhydride and 1,4-butylene glycol wa s carriedout, usingp-toluensulphonic acid as catalyst, . he resulting material was characterized yIR and Ht-NMR spectroscopy, nd group analysis, and gel permeation chromatography.It is shown that there is a relationship between maleate to fumarat,e somerization andsteric interaction among condensed iroups on the one hand and the tendency of the reacting

system o crosslink or gel.

INTRODUCTION

In spite of'all the work which has been carried outon polycondensation of maleic anhydride ( MA ) withdiflerent glycols, t is not clear why the maleate of'umarate somerization occurs. Although it is quitecertain that the glycol structure plays an imp


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1606 LAP.F,Z V. AND PERDOMO MENDOZA

Table I Data from Polyesterification Reactions Table IV P rotonAssignments

Magnetic Resonance

SampleTemperature

( ' c ) Acid Number' ChemicalShift (ppm)

Time(min)

Assignment

30.7 ') n ' ) 1

" Mg KOH/g sarnple

sintered glass nnel. The filtrate was warmed andpetroleum ether added. The mixture was allowed ostand overnight and the upper layer decanted. fh e

remaining material was dried under vacuum (0.1Torr) a l 6o"C for J - -

Analyt ica l Techniques

Molecular weights were determined by end groupanalysis an d gel permeation chromatography.' Thinfilms we re obtained by casting of chlorofbrm solut,ionon NaCl disks, and the IR spectra aken on a ['erkinElmer 377 instrument. Proton magnetic resonanceanalyses were carried out in a Varian A-60 (6 0 MHz)spectrometer, amples being dissolved n CDC13 ndTMS used as internal ref'erence.

Table III Infrared Assignment of MainAbsorption Bands

Absorption (c m 1) Assignment

fumarate form

maleate formC H , C H , C H , O - C -C H , C H , C H , O C -

RESUTTS ND DSCUSSION

Table I summarizes he deta ils of the polymerizationprocess; Table II and V re fers to the characterizatio nof reprecipitated polyester. Th e percentage somer-ization was obtained from NMR spectra. IR an dNMR spectra are shown in Figr.r res and 2, and themain assignments ar e given in Tables III and IV.

Spectroscopic and solubility resu lts confirm thelinearity of this polyester. The two ab sorptions at6.27 and 6.85 pp m indicate the isomerization of ma-leate to fumarate, and NMR measurements ndicatethat it reaches 39%. En d group analysis ndicates arelatively high molecular weight and GPC shows w ofractions (Fig. 3). The fractions could not be easilyseparated by normal reprecipitation.

lJnsaturation wa s confirmed by olefinic absorp-t ions a t . 1070 m 1(H g- ) and 16411 m ' 1C-C in the Il l spectra, and from fumarate (6.811 pm )and maleate 6 .27 ppm) shi f t s n the NMR spect ra .Th e polyester is mainly hydroxv terminated asshown by end group.analysis and IR absorption at3 5 5 0 c m 1 .

The relatively high percentage of isomerizationIies between those for the polyesters rom 1,3-pro-pylene glycol an d 1,2-ethylene glycol. Though thereis one more methylene group in 1,4-butylene glycol,

g c : 1 6 0 ! 1 - ! 0 ' ' 1 a a

{ l n ^ ' ' l

12

A

18 818 8

190190190

6018 0

36 0480540

3 1 2 . 31 3 1 . 6

8 1 . 8u.513 .6

6.85

6.274.221.80

s i n g l e t C H C H

s ing le t-

CH CHs i n g l e t - C - O - Q H ,

- C - O - C H ,

" mS KOH/g sample.

Table II Data fromof the Polyester

End Group Analysis

AcidNumber'

HydroxylNumber

,;Isomerizat ion,,

;19

3550 (small, broad)3450 (small, broad)3070 (small, broad)2980 (medium, sharp)1725 (strong, sharp)1645 (medium, sharp)1190 (strong, sharp)

OH terminal hydroxyOH terminal carboxylC - H olefinicC - H methylenicC O esterC C olefinicC - O - C e s t e r

StretchingStretchingStretchingStretchingStretchingStretchingStretching

F i gu re I I nf ra re d s pe ct ra of the polyester.


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UNSATURATED POLYESTF]RS. II

Table V Data from GPC Analysis

1607

M""

80 7a 6 '0 50, ' ro" , , ,

to 2a 10 oo

Figure 2 Proton magnetic esonance pectra of thepolyester.

th e higher degree of isomerizat,ion, n comparisonwith the polyester from 1,3-propylene glycol,2 ma ybe explained as being due o spatial nteractions be -

tween ester groups in close proximity. Th e glycolsegment, within the polymer chain, could be ar-ranged n a twisted zig,-zag n such a way that somesort of ringlike structure is formed nearby wherethose close ester grclups ma y undergo spatial repul-sion, thus enhancing isomerization.

There may also be a critical point at which sidereactions ik e gelation and crosslinking become ki-netically or energetically more relev ant even thanisomerization or esterification, since he progress ofth e polyesterification eaction s quite slow, as mea-sured by acid number, without any perceptible signof any other process han conversion of maleate intcr

fumarate fbrms. In other words, whenever t is desired to obtain a high molecular weight polyester of'

2 0 2 a 3 0E L U I I O N V C L U M E

Figure 3 Gel permeation chromatographic trace of thepolyester.

2544 4673

MA, the glycol chosen as counterpart fbr the polyes-terification must not endure other side reactionssuch as that of cis-trans isomerization, which nor-mally proceed ogether with polymerization. So, headdition of glycol segments o double bonds ( mainlyto fumarate ) and, fumarate-fumarate double bondreaction, is avoided. The last two reactions ea d tolimited polymerization.

CONCLUSIONS

' I 'he spatial configuration of 'polyester chains is evenmore important than methylene groups within theglycol chain for cis-trans isomerization to occur.When it is impossible to inhibit this isomerization,it could be harmless to polyesterification if ' the crit-ical point fb r gelation or crosslinking is restrained.

We wish to thank CDCHT-tll ,A fbr financial supportduring the course of this work. We also thank ProlessorN. (]rassie or reading he manuscript and fbr his suggestions and comments.

REFERENCES

1. C. ,I. LarezY. and G. A. Perdomo Mendoza, PoNm.BuLl . , 2 (5 -6 ) , 51 : l ( 1989 .

2. C. J. L,arez Y. and G. A. Perdomo Mendoza, PoLvm.Bull. , 23, 577 ( 1990 .

ll . I . Vancz Szmercsnyi, L. K. Maros, and A. A. Za-h a r a n , J . A p p l . S c i . , 1 0 , 5 1 3 1 9 6 6 ) .

4. C. S. Fuller and C. L. Erickson, J. Am. Chem. Soc.,59 , i144 1937 .

5. C. S. Fuller, C. J. Frosch, and N. R. Pape, J. Am.Chem. Soc., 64, 1.54 1942 .

6. A. 'furner-Jones an d C. W. Buan, Acta Cryst. , 15,1 0 5 1 9 6 2 ) .

Receiued December 7, 1990Accepted January 3, 1991

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j app polym sci 43 1605-1607 1991 lárez perdomo

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