chapter -3 ir – spectroscopy and gpc part-a infrared...

Chapter -3 IR – Spectroscopy and GPC

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PART-A

INFRARED SPECTROSCOPY

3.1.[A] INTRODUCTION:

Infrared (IR) spectroscopy is one of the most common spectroscopic technique

used by organic and inorganic chemists. It is the absorption measurement of different

IR frequencies by a sample positioned in the path of an IR beam. The main goal of IR

spectroscopic analysis is to determine the chemical functional groups present in the

sample. IR spectroscopy may also be conveniently applied to study the progress of

polymerization reactions by focusing on intensity changes of the absorption bands,

which are either characteristic of the monomeric starting materials or the final

polymeric product. Infrared radiation was discovered in 1800 by Sir William Herschel

[1].

IR spectroscopy is the spectroscopy which deals with the infrared region of the

electromagnetic spectrum with a longer wavelength and lower frequency than visible

light. It covers a range of techniques, mostly based on absorption spectroscopy. IR

spectroscopy is used in quality control, dynamic measurement and monitoring

applications such as the long-term unattended measurement of CO2 concentrations in

green houses and growth chambers by infrared gas analyzers. It is also used in

forensic analysis, for both criminal and civil cases.

The process development in the carbon fiber industry could, in principle, be

applied to light weight automobile parts that would reduce energy consumption.

Therefore, many types of precursors are under investigation to test the feasibility for a

large scale economical production route to carbon fibers [2-4]. IR has been used to

characterize polymer blends, dynamics, surfaces and interfaces as well as

chromatographic effluents and degradation products. The empirical information on IR

spectra is based on the concept of nearly independent vibration atomic groups in the

macromolecule (group frequencies concept) [5]. Studies of polymers were among the

first applications of the method [6,7]. In recent years, with the introduction of

commercial Fourier Transformation Infrared (FT-IR) spectrometer that are operable

over the entire IR frequency range, has many applications of IR analysis that were

impossible or at least extremely difficult using conventional dispersive instruments


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are now readily accomplished [8]. FT-IR spectroscopy has several advantages over

conventional depressive IR spectroscopy [9,10] technique.

Slevamalar and co-workers prepared new functional methacrylic monomer 4-

benzyloxy carbonyl phenyl methacrylate by reacting benzyl-4-hydroxy benzoate with

methacryloyl chloride in presence of triethylamine and copolymerized this monomer

with glycidyl methacrylate (GMA). They characterized the copolymers by FT-IR, 1H-

NMR and 13C-NMR spectroscopic techniques [11]. Patel et al[12] synthesized 4-

chloro-3 methyl phenyl methacrylate with 8-Quninolinyl methacrylate in different

feed ratios and FT-IR spectroscopy were used to characterize the copolymers..

Nermina et al [13] prepared 2,4,6- trichlorophenyl acrylate emultion template porous

polymers and polymers were characterized by scanning electron microscope, FT-IR

spectroscopy, elemental analysis and mercury intrusion porosimetry. Synthesis of

alkali soluble copolymers of butyl acrylates/acrylic acid and its characterization by

FT-IR were done by Jin et al [14]. Yang and co-workers [15] synthesized copolymers

of MMA with N-(p-tolyl) maleimide (NPTMI) and determined the molecular weight

of these copolymers by GPC. The results showed that the nM and wM increases

when the NPTMI feed content is increased.

Bozkurt and Karadedelia [16] synthesized copolymers of 4(5)-vinylimidazole

and ethyleneglycol methacrylate phosphate and characterized the copolymers by 1H-

NMR and FT-IR spectroscopy. Durgun and co-workers [17] synthesized [2-oxo-2-(4-

methyl) phenyl amino] ethylene methacrylate and copolymerize with Styrene, these

copolymers were characterized FT-IR spectroscopy. Vijayanand and co-workers [18]

polymerized 3,5-dimethyl phenyl acrylate with methyl methacrylate and characterized

the polymers by FT-IR and 1H-NMR spectroscopy. 1,4-pentadiene-3-one-1-p-

hydroxyphenyl-5-phenyl methacrylate monomer was synthesized by Reddy B S R and

Arun [19]. The copolymerized this monomer with methyl acrylate and with N-vinyl

pyrrolidone using different feed compositions. All these polymers were characterized

by FT-IR spectroscopy. Gao and co-workers [20] prepared di-block copolymers

consisting of poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} with poly(butyl

acrylate). They used GPC in order to characterize the prepared copolymers and

reported that these copolymers had high molecular weights and relatively narrow

polydispersities (polydispersity index < 1.20).


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Ray and co-workers [21] reported acrylic based copolymeric hydrogel

nanopartical used in drug delivery system and characterized it by FT-IR analysis. Gao

and coworkers [22] prepared three component system comprises of poly(acrylamide-

co-acrylic acid) /poly(vinyl pyrrolidone) [p(AM-co-AA)/PVP] polymer blend by

dispersion polymerization technique. Fourier transform infrared spectra (FT-IR) of

prepared polymer blend shows that intramolecular hydrogen bonding interaction

occurred between the dispersed phase and the continuous phase. Soykan and co-

workers [23] synthesized N-(4-bromophenyl)-2-methacrylamide monomer and

copolymerized it with 2-hydroxy methacrylate with different feed ratio. Further they

characterized copolymers by FT-IR, NMR spectroscopy. J.Sim and co-workers [24]

synthesized PSA are made from OH functional acrylate matrix which is reacted with

2-methacryloyloxy ethyl isocynate (MOI) to give UV curable double bond. Bozkurt

and karadedelia [25] synthesized copolymers of 4(5)-vinylimidazole and

ethyleneglycol methacrylate phosphate and characterized the copolymers by 1H-NMR

and FT-IR spectroscopy.

Radical photopolymerization of (meth)acrylates in the presence of dissolved

poly heteroarylenes has been investigated. The kinetics of radical polymerization of

unsaturated monomers in presence of polyheteroacrylenes and model compounds has

been studied by differential scanning photocalorimetry and infrared spectroscopy

[26]. Gokceoren and co-workers [27] analysed the free radical copolymerization of N-

vinyl carbazole(NVCz) with acrylic acid (AA), itaconic acid (IA)and N-isopropyl

acrylamide(NIPAAm) at different feed ratios were conducted in 1,4-dioxane at 50℃.

The copolymers were characterized by UV and FT-IR spectroscopic techniques.

Hiren and co-workers [28] synthesized methylmethacrylate and maleimide

copolymer. The copolymer was characterized by FT-IR analysis. Taghizadeh and

Ghazemi [29] reported acrylic based copolymer which are used as pressure sensitive

adhesive. The characteristic absorption bands of –COC, -C=O, and –CH2 and –CH3

are shown at 1165, 1733 , and 2850-3000 cm-1 respectively. The disappearance of a

band at 1600 cm-1 is an indication of the absence of monomer impurities.

Chen and co-workers [30] studied the kinetics of radical polymerization of -

hydroxyethyl methacrylate by in-situ IR spectroscopic method. The variation of C=C

peak intensity was monitored continuously by IR spectroscopy during the


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polymerization. The conversion rate and the apparent polymerization rate constant

were calculated using C=O absorption peak of the system as an internal standard.

Hummel and co-workers [31] studied the reaction kinetics for the thermal

polymerization of aliphatic bismaleimides by IR spectroscopy. It was observed that

the intensity of the absorption band at 3100 cm-1 (=CH band of the maleimide moiety)

decreased with time as the polymerization progressed. Manju and co-workers [32]

prepared methyl methacrylate (MMA) with 2-ethoxyethyl methacrylate (2-EOEMA)

and their copolymers. They characterized these monomers and polymers by FT-IR, 1H

and 13C NMR spectroscopy.

IR spectroscopy technique is much simpler as compared to other methods of

vibrational spectroscopy. In order to record an IR spectrum, in most cases the polymer

is brought on to discs of NaCl or KBr either as a thin solid film (made from polymer

solution in a volatile solvent) or as an homogeneous suspension in paraffin oil,

alternatively, solid polymers can be milled together with a large excess of KBr, and

the resulting powder can be compressed to a (homogeneous, transparent) disc. Today

the FT-IR spectroscopy has several advantages over conventional depressive IR

spectroscopy technique.

Characterization of VMA copolymers by FT-IR spectroscopy is given in this

part of the chapter.

3.2. [A] EXPERIMENTAL:

FT-IR Spectrum of homo and copolymers were recorded using Perkin-Elmer

FT-IR series 300, spectrum GX spectrophotometer on solid KBr pellet.


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Figure 3.1: FT-IR Spectra of Poly(VMA), Poly(VMA-co-MA) and Poly(MA).


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Table 3.1: FT-IR spectral data for poly(VMA), poly(MA) and poly(VMA-co-MA).

Sample

Code

No.

υCHO

stretching

(cm-1)

υC=C

stretching

in aromatic

ring (cm-1)

δC-O-C

bending

(cm-1)

υC=O

stretching

(cm-1)

υCOO

ester

ketone

(cm-1)

δsyCH3

(cm-1)

δasyCH3

(cm-1)

ortho

disubtituted

benzene

in aromatic

ring (cm-1)

υC-CH3-CH

streching

(cm-1)

υC-O-C

bending

(cm-1)

υCH3-O

stretching

(cm-1)

1 2736,2849 1503,1597 1270,1201 1702 1758 1390 1465 732 - - -

2 2848 1503,1598 1270 1702 1753 1388 1465 732 2942 1150 3070

3 2851 1505,1599 1271 1701 1757 1390 1466 732 2950 1148 3069

4 2737,2852 1504.1599 1271 1671 1737 1388 1466 732 2948 1149 3069

5 2739,2851 1503,1599 1271 1701 1738 1390 1466 732 2952 1149 3069

6 2852 1458,1622 1272 1701 1740 1384 1458 733 2923 1119 3069

7 - - 1265 1736 - 1385 - - 29551197,

11643000


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Figure 3.2: FT-IR Spectra of Poly(VMA), Poly(VMA-co-MCMA) andPoly(MCMA).


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8

Table 3.2: FT-IR spectral data for poly(VMA), poly(MCMA) and poly(VMA-co-MCMA).

Sample

Code

No.

υCHO

stretching

(cm-1)

υC=C

stretching

in aromatic

ring

(cm-1)

δC-O-C

bendin

g

(cm-1)

υC=O

stretching

(cm-1)

υCOO

ester

ketone

(cm-1)

δsyCH

3

(cm-1)

δasyCH3

(cm-1)

ortho

disubtituted

benzene

in aromatic

ring (cm-1)

υC-H

streching

in

aromatic

ring

(cm-1)

υC-H

streching

in

alkyl

group (cm-

1)

δlactone

ring

stretching

(cm-1)

1 2736,2849 1503,1597 1270 1702 1735 1390 1465 732 3072 2995,2944 -

8 2736,2850 1503,1597 1267 1700 1734 1388 1465 732 3072 2987,2943 1756

9 2853 1503,1599 1265 1702 1732 1387 1465 732 3072 2983,2935 1758

10 2853 1503,1572 1264 1702 1731 1387 1465 732 3073 2983,2937 1757

11 2741,2852 1502 1264 1703 1731 1388 1450 733 3075 2988,2927 1756

12 2856 1502,1571 1263 1703 1731 1387 1445 733 3077 2988,2926 1754

13 - 1570 1262 - 1731,1756 1388 1442 - 3085 2988,2928 1756


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Figure 3.3: FT-IR Spectra of Poly(VMA), Poly(VMA-co-4CMA) and Poly(4CMA).


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Table 3.3: FT-IR spectral data for poly(VMA), poly(4CMA) and poly(VMA-co-4CMA).

Sample

Code

No.

υCHO

stretching

(cm-1)

υC=C

stretching

in

aromatic

ring

(cm-1)

δC-O-C

bending

(cm-1)

υC=O

stretching

(cm-1)

υCOO

ester

ketone

(cm-1)

δsyCH3

(cm-1)δasyCH3

(cm-1)

ortho

disubtituted

benzene

in aromatic

ring (cm-1)

υC-H

streching

in

aromatic

ring (cm-1)

υC-H

streching

in alkyl

group

(cm-1)

δlactone

ring

stretching

(cm-1)

1 2736,2849 1503,1597 1270 1702 1735 1390 1465 732 3072 2995,2944 -

14 2736,2856 1501,1597 1270 1659 1728 1390 1465 733 3072 2995,2930 1758

15 2737,2852 1502,1568 1270 1690 1729 1379 1453 732 3074 2995,2939 1759

16 2737,2856 1502,1567 1271 1690 1729 1379 1453 733 3074 2995,2938 1758

17 2737,2856 1503,1568 1271 1664 1728 1388 1452 733 3074 2995,2931 1760

18 2856 1506,1564 1274 1664 1728 1380 1452 733 3074 2995,2934 1760

19 - 1568 1274 - 1729 1378 1452 - 3074 2991,2929 1762


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Figure 3.4: FT-IR Spectra of Poly(VMA), Poly(VMA-co-PCPMA) andPoly(PCPMA).


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Table 3.4: FT-IR spectral data for pol y(VMA), poly(PCPMA) and poly(VMA-co-PCPMA).

SampleCodeNo.

υCHO

stretching(cm-1)

υC=C

stretchingin

aromaticring

(cm-1)

δC-O-C

bending(cm-1)

υC=O

stretching(cm-1)

υCOO

esterketone(cm-1)

δsyCH3

(cm-1)δasyCH3

(cm-1)

orthodisubtituted

benzenein aromaticring (cm-1)

υC-H

strechingin

aromaticring

(cm-1)

υC-H

strechingin

alkylgroup(cm-1)

υC-H

out ofplane

bending inphenyl

ring(cm-1)

υC-Cl

(cm-1)

1 2736,2849 1503.1597 1270 1702 1758 1390 1465 732 - - 2995,2944 -

20 2737,2850 1501,1596 1268 1667 1755 1389 1463 732 3073 869 2939,2850 661

21 2737,2852 1501,1596 1268 1670 1754 1389 1464 733 3073 872 2987,2933 662

22 2737,2852 1501,1597 1268 1664 1753 1390 1464 733 3075 874 2987,2934 664

23 2729,2852 1501,1597 1269 1668 1753 1390 1487 733 3075 875 2995,2938 664

24 2729,2852 1501,1596 1263 1673 1752 1389 1487 734 3100 877 2995,2935 668

25 - - 1256 1666 1751 1390 1487 - 3123 878 2995,2936 666


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Figure 3.5: FT-IR Spectra of Poly(VMA), Poly(VMA-co-GMA) and Poly(GMA).


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Table 3.5: FT-IR spectral data for poly(VMA), poly(GMA) and poly(VMA-co-GMA).

Sample

Code

No.

υCHO

stretching

(cm-1)

υC=C

stretching

in

aromatic

ring (cm-

1)

δC-O-C

bending

(cm-1)

υC=O

stretching

(cm-1)

υCOO

ester

ketone

(cm-1)

δsyCH3

(cm-1)

δasyCH3

(cm-1)

ortho

disubtituted

benzene in

aromatic ring

(cm-1)

υC-O

streching

of epoxy

group (cm-1)

υC-H

stretching in

alkyl group

(cm-1)

1 2736,2849 1503,1597 1270 1702 1735 1390 1465 732 - 2944

26 2737,2849 1502,1596 1267 1666 1728 1390 1464 732 990 2939

27 2737,2849 1503,1597 1269 1664 1728 1391 1464 734 990 2926

28 2737,2852 1503,1597 1269 1664 1729 1390 1466 733 990 2937

29 2739,2852 1502,1598 1269 1701 1726 1389 1463 733 992 2934

30 2852 1501,1597 1269 1701 1726 1390 1458 735 989 2939

31 - - 1271 - 1723 1389 1450 - 989 2934


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Figure 3.6: FT-IR Spectra of Poly(VMA), Poly(VMA-co-8-QMA) and Poly(8-

QMA).


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QMA).


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QMA).


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Table 3.6: FT-IR spectral data for poly(VMA), poly( 8-QMA) and poly(VMA-co-8-QMA).

SampleCodeNo.

υCHO

stretching(cm-1)

υC=C

stretchingin

aromaticring

(cm-1)

δC-O-C

bending(cm-1)

υC=O

stretching(cm-1)

υCOO

esterketone(cm-1)

δsyCH3

(cm-1)

orthodisubtituted

benzenein aromaticring (cm-1)

υC-O-C

strechingin

aromaticring

(cm-1)

υC-H

strechingin

aromaticring(cm-1)

υC=O

stretchingof 8-o-sub.Quinolinoylring (cm-1)

1 2736,2849 1503,1597 1270 1702 1758 1390 732 1201 3072 -

32 2735,2851 1503,1596 1268 1700 1757 1389 731 1201 3069 1466,1503

33 2737,2852 1502,1595 1267 1669 1756 1388 731 1201 3069 1467,1502

34 2737,2856 1507,1603 1240 1659 1756 1390 731 1174 3069 1464,1507

35 - 1502,1596 1262 1665 1754 1388 731 1154 3069 1467,1502

36 - 1503,1595 1263 1663 1748 1387 710 1162 2930 1469,1503

37 - 1504,1578 1274 - 1727 1380 - 1224 3046 1471,1504


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3.3. [A] RESULTS AND DISCUSSION:

Figure 3.1 to 3.6 shows the comparative FT-IR spectra of the homopolymers

as well as copolymers of VMA with MA, MCMA, 4-CMA, PCPMA, GMA and

QMA respectively. The important IR frequencies and their assignments are tabulated

in tables 3.1 to 3.6. These spectra provides qualitative information about the various

functional group and structure of the copolymers. The copolymer spectra shows all

the bands contributed by both the components of the copolymer system.

In the spectrum of poly(VMA), two sharp bands at 2736 cm-1 and 2849 cm-1

due to CHO of aldehyde group are observed, where as the band at 1702 cm-1 due to

C=O stretching for aldehyde and ketone double bond. The band at 1270 cm-1may be

due to C-O-C bending of CH3-O aromatic ring. The sharp band at 732 cm-1 confirms

the presence of ortho-disubstituted benzene. The spectrum of poly (VMA) shows

three bands at 1465, 1503 and 1597 cm-1 which are characteristic absorptions of

phenyl ring. The band at 1735 cm-1 may have contribution from ester-ketone group

and interestingly the relative intensity of this band is decreased with decrease in VMA

content in the copolymers. The band at 1390 cm-1 confirms the presence of methyl

group and the strong absorption at 1465 cm-1 may be due to C-H bending vibrations

of CH3 group.

The IR spectrum of poly(MA) shows the C-H stretching vibration of alkyl

group at 2955 cm-1 and 3000 cm-1. Bands at 1385 cm-1 may be assigned to the C-H

bending vibrations of methyl group. Two strong absorptions, one at 1736 cm-1 and the

other at 1265 cm-1 have contributions respectively from C=O and C-O stretching

mode of the ester group.

The IR spectrum of poly (MCMA) shows the band at 3085 cm-1 due to C-H

stretching vibration of the aromatic ring. The two medium bands at 2988 and 2928

cm-1 are due to symmetric and antisymmetric stretching of CH3 groups where as

absorption at 1442 cm-1 may be due to bending vibration of CH2 group. The strong

absorption at 1388 cm-1 may be C-H stretching vibrations of CH3 and CH2 groups.

The broad band at 1731 cm-1 is due to C-O stretching vibration of ester group and

band at 1756 cm-1 is due to lactone ring. The sharp band at 1262 cm-1 and a broad

band at 1147 cm-1 are assigned to C-O stretching vibration of ester group.


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The IR spectrum of poly(4-CMA) shows the band at 3074 cm-1 is due to C-H

stretching vibration of aromatic ring. The two medium bands at 2991 and 2929 cm-1

are due to symmetric and asymmetric stretching of CH3 groups where as 1442 cm-1

may be due to bending vibration of methylene group. The broad band at 1729 cm-1 is

assigned to C=O stretching vibration of ester group and band at 1762 cm-1 is due to

lactone ring. The absorption band at 1378 cm-1may be C-H stretching vibration of

methyl and methylene groups.

In the IR spectrum of poly (PCPMA), the medium bands at 2995 and 2936 cm-

1 may be assigned to the asymmetric and symmetric C-H stretching vibration of

methyl and methylene groups. The C-H stretching vibration of aromatic ring is

observed at 3123 cm-1. The sharp band at 1751 cm-1 may have contribution from C=O

stretching vibration of ester group. The spectrum of this compound shows the

characteristic absorption of ortho substituted phenyl ring at 1487 and 1666 cm-1. The

sharp band at 666 cm-1 is attributed to C-Cl stretching frequency.

In the IR spectrum of poly (GMA), the band at 2934 cm-1 is due to C-H

stretching vibration of methyl group. A broad peak at 989 cm-1may have contribution

from C-O stretching of epoxy group. The symmetric C-H bending mode of CH3 group

is assigned to band at 1389 cm-1. The 1723 cm-1peak have contribution from C=O of

ester group of GMA.

In poly(8-QMA) spectrum, two sharp bands at 1727 and 1224 cm-1 may have

contribution from υC=O and υC-O stretching vibration of ester group. The poly(8-QMA)

spectrum also show strong band at 1471 cm-1 which may be due to the characteristic

absorption of the 8-o-substituted quinolinyl ring system.

The relative intensities of characteristic group frequency bands in the

copolymers are observed cancelled according to the change in the copolymer

composition and the extent of change in the relative band intensities of characteristic

group frequencies of each component may have some correlation with the copolymer

composition.


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PART-B

GEL PERMEATION CHROMATOGRAPHY (GPC)

3.1.[B]. INTRODUCTION

An elegant method used for the analysis of fraction of polymer is Gel

Permeation Chromatography (GPC). GPC is one of the most powerful and versatile

analytical technique available for understanding and predicting polymer performance.

Gel permeation chromatography (GPC) which is more correctly termed as size

exclusion chromatography (SEC), is a separation method for polymers and provides

relative molecular weights [33-36]. The technique when applied by biologist for the

separation of proteins from a mixture is called gel filtration chromatography and by

colloid chemists to separate colloidal dispersion according to size is called size

exclusion chromatography. The molecular weight and molecular weight distribution

are most fundamental characteristic of a polymer sample and it is the only technique

for characterizing a polymer by its complete molecular weight distribution, which

includes, wM , M z and M n [37]. Porath and Flodin [38] reported the first effective

demonstration that polymers may be separated by the size dependence of degree of

solute penetration into a porous packing.

The GPC technique was developed by Moore [39] at the Dow Chem. Co.,

U.S.A. in the early 1960’s and the preparatory column technology developed by him

was licensed to Waters associated by DOW. Waters subsequently commercialized the

GPC technique by introducing the first GPC instrument (GPC-100) to the market in

1964. This was a major step over the classical fractionation procedures that typically

required many days, even weeks, to fully characterize the molecular weight

distribution (MWD) of a polymer sample [40]. Since then, the rapid development in

high pressure solvent transport system, high sensitivity detectors of low cell volume,

polystyrene gel bead processing technology, data acquisition and processing

softwares, have made it possible today to obtain the polymer molecular weights and

MWD data in less than 20 min. with high accuracy and reproducibility.

Commercial synthetic polymers have broad distributions of molecular weight,

and it is therefore necessary to report an average molecular weight when

characterizing a polymer. The molecular weight distribution (MWD) is characterized

by several parameters, the most important of which are as follows:


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The number average molecular weight: i

i

NiMiMn

Ni

The weight average molecular weight:

2

i

i

NiMiMw

NiMi

The z average molecular weight:

3

2i

i

NiMiM z

NiMi

Where: Ni = the number of molecules in the ith molecular weight state

Mi = the molecular weight of the ith molecular weight state.

In addition, the ratio of wM to nM is often used as a measure of the

“broadness” of the distribution. This ratio is usually termed as “polydispersity”.

nM values provide information on polymer viscosity and strength, while wM

value relate to flexibility and properties affected by the degree of polymer

crystallinity. The wM values are sensitive to the amount of high molecular weight

molecules present while the nM values reflect sensitivity to the amount of low

molecular weight molecules present.

All the average molecular weights and its molecular weight distribution

(MWD) are the most fundamental characteristic of a high molecular weight polymers

and has great practical importance since they directly affect many of its characteristic

physical properties such as tensile, modulus of elasticity (before cross-linking), melt

viscosity, brittleness, hardness, softening temperature, elongation at tensile break,

impact strength, tear strength, low temperature toughness, resistance to environmental

stress cracking, drawability, adhesive task, strength and cure time. Even differences in

a polymer molecular weight distribution (MWD) may affect the important processing

properties. For a given set of process conditions, such molecular variations may result

into common production problems, such as flashing. The relative amount of different

size and shape of the molecules in a polymer known as the molecular weight


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distribution is a critical parameter to be controlled for producing a polymeric product

with desired performance characteristics.

The literature survey reveals that there are some reports on the applications of

GPC technique to understand the physical behavior of the high polymers. Vijayanand

and others [41] determined the number average and weight average molecular weight

and polydispersity index of homo polymer and 3,5-dimethyl phenyl acrylate(DMPA)

and its copolymer with MMA by gel permeation chromatography. The polydispersity

values of the copolymers suggest that chain termination takes place by

disproportionation when the mole fraction of MMA in the feed is high and radical

recombination was predominant when the mole fraction of DMPA was high in the

feed.

Naghash Hamid Javaherian [42] reported Triphenylvinyl silan(TPVS)

containing Vinyl acetate (VAc) , Butyl acrylate (BA) and N-Methyloacrylamide

(NMA) copolymers were prepared by emulsion polymerization. The resulting

copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR)

and Gel permeation chromatography (GPC). The obtained copolymers have high solid

content (50%) and can be used in weather resistant emulsion paints as a binder. Li

Wang and co-workers [43] utilizes GPC technique for calibration of standard

polystyrene by using THF as eluant on a WATER 1515 GPC instrument,eluting rate

at 1 ml/min.

Zhu and co-workers [44] reported on preparation and self assembly behavior

of poly styrene – block–poly(dimethyl amino ethyl methacrylate) amphiphilic block

copolymers using atom transfer radical polymerization (ATRP). The molecular

weight of synthesized polymers were obtained by GPC. Novel way to prepare block

copolymers is presented by Jiang and co-workers [45]. Copolymers of α-methyl

styrene and GMA were synthesized (PAG). Further block copolymerization was done

between PAG and STY as well as MMA. The resulting block copolymers were

characterized by GPC. nM for poly(AMS)-block-poly(STY) was 44700 while for

poly(AMS)-block-poly(MMA) was 63100 where as nMwM / was found to be 4.63

and 1.77 respectively. Shen et al. [46] reported on synthesis and properties of novel

brush type copolymer bearing thiophene backbone and 3-(N-carbazolyl) propyl

acrylate side chain for light emitting application. GPC technique was used to find

molecular weight of the synthesized polymers.


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Sreekuttan and co-workers [47] prepared new acrylic monomer 4-

propanoylphenyl acrylate (PPA) and copolymerized it with methyl methacrylate

(MMA). The molecular weights ( wM and nM ) of the copolymers were determined by

GPC. Brar and Saini [48] copolymerized acrylonitrile and 2-methoxyethyl acrylate at

three different molar feed compositions weres carried out by atom transfer radical

polymerization (ATRP) using 2-bromopropionitrile as initiator and CuCl/2,2′-

bipyridine as catalyst system in ethylene carbonate at 60°C by ATRP. The prepared

copolymers were characterized by GPC and the result indicates linear increase in

molecular weight with conversion and low polydispersities were observed for all the

copolymers. Isemura and co-workers [49] synthesized poly(2-(perfluoroalkyl)ethyl

acrylate-co-alkyl acrylate) and determined molecular weight distribution by size

exclusion chromatography using an appropriate mobile phase such as a mixture of

HCFC225 and THF.

Kadir and co-workers [50] synthesized copolymers from phenyl methacrylate

(PMA) and methyl methacrylate (MMA). Yavuz and Erol [51] prepared copolymers

of (2-oxo-2-tert-butylamino) ethylene methacrylate (TBAMA) with styrene in 1,4-

dioxane by free radical polymerization and determined weight average and number

average molecular weights using gel permeation chromatography. Chen and co-

workers [52] synthesized fluorine containing polyacrylate and determined molecular

weight of the synthesized polymers by GPC. They reported average molar mass

( nM ) as 51,332 and the polydispersity is 5.8.

Due to extensive research development especially in the field of pumping

system, column technology, detector system, method of calibration, data acquisition

and processing softwares have been possible and consolatory huge number of

references are available in the literature on the GPC techniques [53-56]. G.Wang and

Hu Wu [57] synthesized microwave- assisted controlled copolymerization of styrene

and acrylonitrile catalyzed by FeCl3 / isophalic acid. The resultant copolymer

characterized by GPC, FT-IR and NMR.

The characterization of VMA copolymers with several vinyl monomers by

GPC is discussed in this part of a chapter.


Page 103

3.2.[B]. EXPERIMENTAL

a. Average Molecular Weight and Polydispersity

A Jasco GPC instrument equipped with PU1580 multi solvent delivery

system, Rheodyne 7725i manual injector and Shodex RI 7A detector was used for

GPC analysis. Flow rate of DMF was 1.0 ml/min and temperature of the column was

kept 40°C. The sample size was 20 micro liters of a 0.1 % w/v solution was selected

in mobile phase so that dynamic range of the RI detector was not exceede.

GPC system was calibrated with ten narrow molecular weight polystyrene

standards having reported peak molecular weights from 875 to 495000. The sample

was filtered through 5 micron PTFE filter. A calibration curve of retention time vs log

molecular weight was established and used for the determination of molecular

weights of copolymers. Clarity GPC software was used to calculate the nM , wM , zM

and nMwM / values.

b. Solution Viscosity Measurement

Schott-Gerate viscosity measurement system consisting of water bath with

mechanical stirrer, precise temperature controller, Ubbelohde viscometer and

automatic flow time measuring device was used to determine the viscosity of

polymers and all the measurements were carried out at 25+0.1ºC temperature. 50 mg

polymer sample was dissolved in 50 ml DMF and the resulting solution was filtered.

Both, solvent flow time (to) and solution flow time (t) were measured on the same

viscometer. The intrinsic viscosity [] was calculated by single point method using

the following expression [58],

Intrinsic Viscosity [] = ]ln[2

1relspC

Where, C = Concentration g.dl-1

rel = relative viscosity = (t / to)

sp = specific viscosity = [rel - 1]


Page 104

Table 3.7: GPC and viscosity data for homo and copolymers of VMA with MA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

2 23162 48640 99130 2.10 0.165

4 22560 42864 94230 1.90 0.155

6 24785 46595 83590 1.88 0.201

7 28350 42808 43980 1.51 0.136

Table 3.8: GPC and viscosity data for homo and copolymers of VMA with MCMA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

8 26790 51972 81072 1.94 0.181

10 28080 51386 75035 1.83 0.186

12 29005 53949 60286 1.86 0.219

13 27948 48070 62495 1.72 0.199

nM wM zM

nM wM zM


Page 105

Table 3.9: GPC and viscosity data for homo and copolymers of VMA with 4-CMA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

14 25670 49286 95600 1.92 0.196

16 25990 55878 80360 2.15 0.142

18 23500 52875 71250 2.25 0.138

19 8406 28384 75297 3.37 0.122

Table 3.10: GPC and viscosity data for homo and copolymers of VMA with PCPMA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

20 26760 50041 87160 1.87 0.09

22 25325 48370 58464 1.91 0.114

24 24150 47575 51750 1.97 0.131

25 25601 46850 42597 1.83 0.140

nM wM zM

nM wM zM


Page 106

Table 3.11: GPC and viscosity data for homo and copolymers of VMA with GMA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

26 26110 51697 63600 1.98 0.164

28 25890 50486 48431 1.95 0.184

30 25624 46635 70030 1.82 0.215

31 28230 47426 68755 1.68 0.209

Table 3.12: GPC and viscosity data for homo and co32450polymers of VMA with 8-QMA.

Sample

Code No.

Polydispersity

nMwM /

Intrinsic

viscosity

[] dl.g-1

1 26190 53250 162863 2.03 0.176

32 28572 54001 60399 1.89 0.166

34 27430 50745 32450 1.85 0.155

36 27455 48595 40786 1.77 0.173

37 21305 40480 37142 1.90 0.143

nM wM zM

nM wM zM


Page 107

Figure 3.7: GPC curves for poly(VMA) and poly(VMA-co-GMA).


Page 108

3.3.[B]. RESULTS AND DISCUSSION

The values of average molecular weights, polydispersity and intrinsic viscosity

obtained by GPC for the copolymers of VMA with MA, MCMA, 4-CMA, PCPMA,

GMA and 8-QMA are presented in Tables 3.7 to 3.12.

It is observed from the GPC data of poly(VMA) that the values of nM , wM ,

zM and nMwM / are 26190, 53250, 162863 and 2.03 respectively whereas intrinsic

viscosity [] is 0.176 dl.g-1.

In poly(VMA-co-MA), the values for nM , wM , zM and nMwM / which

ranges from 22560 to 24785, 42864 to 48640, 83590 to 99130 and 1.88 to 2.10

whereas intrinsic viscosity [] is 0.155 to 0.210dl.g-1. For poly(MA) the values of nM

, wM , zM and nMwM / is 28350, 42808, 43980 and 1.51 respectively and

intrinsic viscosity [] is 0.136 dl.g-1. It is observed from these results that molecular

weights and polydispersity index decreases as VMA content decreases in copolymer

while intrinsic viscosity changes randomly i.e. increases or decreases in copolymer.

In case of poly(VMA-co-MCMA), with different feed compositions the GPC

data reveals that the values of nM , wM , zM and nMwM / which ranges from

26790 to 29005, 51972 to 53949, 60286 to 81072 and 1.83 to 1.94 respectively

whereas intrinsic viscosity [] is 0.181 to 0.219 dl.g-1. For poly(MCMA) the values of

nM , wM , zM and nMwM / are 27948, 48070, 62495 and 1.72 respectively and

intrinsic viscosity [] is 0.199 dl.g-1. The results indicates that decreases in the VMA

content in the copolymers, molecular weights and viscosity increases while

polydispersity index changes randomly.

The GPC and viscosity data for poly(VMA-co-4-CMA), provided the values

of nM is from 23500 to 25670, wM is from 49286 to 52875, zM is from 71250 to

95600 and nMwM / ranges from 1.92 to 2.25 whereas intrinsic viscosity [] ranges

from 0.138 to 0.196 dl.g-1. For poly(4-CMA) the values of nM , wM , zM and

nMwM / are 8406, 28384, 75297 and 3.37 respectively and intrinsic viscosity [] is

0.122 dl.g-1. The result reveals that molecular weights and intrinsic viscosity changes

randomly and polydispersity index increases as the VMA content decreases in

copolymer.


Page 109

In poly(VMA-co-PCPMA),the values for nM , wM , zM and nMwM / are


whereas intrinsic viscosity [] ranges from 0.09 to 0.131 dl.g-1. For poly(PCPMA) the

values of nM , wM , zM and nMwM / are 25601, 46850, 42597 and 1.83

respectively and intrinsic viscosity [] is 0.140 dl.g-1. The data reveals that molecular

weights decreases while intrinsic viscosity and polydispersity increases as VMA

content decreases in copolymer chain.

In poly(VMA-co-GMA), the values for nM , wM , zM and nMwM / are


whereas intrinsic viscosity [] ranges from 0.164 to 0.215 dl.g-1. For poly(GMA) the

values of nM , wM , zM and nMwM / are 28230, 47426, 68755 and 1.68

respectively and intrinsic viscosity [] is 0.209 dl.g-1. It is observed from these results

that molecular weights and polydispersity index decreases while viscosity increases as

VMA content decreases in copolymer. The comparative GPC curves of poly(VMA),

poly(VMA-co-GMA) and poly(GMA) are shown in figure 3.7.

For different copolymers of VMA with 8-QMA, the values for nM , wM , zM

and nMwM / and intrinsic viscosity [] ranges from 27430 to 28572, 48595 to

54001, 32450 to 60399, 1.77 to 1.89 and 0.155 to 0.173 respectively. For poly(QMA)

the values of nM , wM , zM and nMwM / are 21305, 40480, 37142 and 1.90

respectively and intrinsic viscosity [] is 0.143 dl.g-1. The result reveals that

molecular weight and polydispersity index decreases as the content of VMA in the

copolymer decreases.

The overall examination of GPC and intrinsic viscosity of the copolymers

system leads to the conclusion that, the values of various average molecular weights

of the copolymer increase in the order nM < wM < zM which is as per the expected

trend reported in the literature [59]. The theoretical values of nMwM / for polymers

produced via radical recombination and disproportionate are 1.5 and 2.0 respectively

[60].


Page 110

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