PROCEEDINGS OF THE 2ND EUROPEAN SYMPOSIUM ON POLYMER SPECTROSCOPY AND
MEETING ON PROBLEMS OF COPOLYMER STATISTIC
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Preface - C. TOSI |
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Alphabetical list of participants |
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Words of welcome - G. CRESPI |
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Opening speech - C. TOSI |
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I - GENERAL LECTURES |
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- Pyro-field ion mass spectrometry; gas chromatography,
and infrared spectroscopy to investigate degradation behaviour and structure
of polymaleic anhydride as well as maleic anhydride - isobutene copolymers
- D.O. HUMMEL, F.H.cT. SADOWSKI, D. WIDDERSHOVEN &, H.-J. DtissEL. |
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Summary - Maleic anhydride (MAH) was polymerized homogeneously
in acetic anhydride under the influence of yradiation. The copolymerization
with isobutene (IB) succooded in benzene (heterogeneously) or in aceto ne
(homogeneously) to yield 8. coloudess, l : l alternating copolymer. PMAH,
PIB, and PIBMAH were investigated by 8 combination of pyrolytic gas chromatography,
infrared spectroscopy, and (pyro-) field ion mass spectroscopy. PMAH yields
00. and CO in aratio of 4 : l as well as a mixture of paraffinic, olefinic,
aromatic and alkyl-aromatic hydrocarbons. A degradation mechanism involving
side-group stripping, with consequent cyclization reactions and statistica
l main chain breaks is suggested.
PIEMAH yieldsCO. and CO in a ratio of3..'5: l as wellasIB,alkyl-substituted
MAH,saturated and unsaturated fatty acids, succinic acid, aliphatic and
alkyl-aromatic hydrocar- bons. According to these results, the structure
of PIBMAH is alternating, containing the IB-units in a head-to-tail fashion. |
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The microstructure of polybutadiene sequences in (acrylonitrile-butadiene)
copolymers studied by IR and NMR - Q. T. PHAM, J. VIALLE & J. GUILLOT |
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Summary - The microstructure of radical (acrylonitrile-butadiene)
copolymers, obtained in dimethylformamide solvent, has been studied by IR
and NMR. It has been shown that, in the butadienerich copolymers, the long
butadiene sequences bave the same microstructure as radical butadiene homopolymers.
While, in the acrylonitrilerich copolymers, the isolated butadiene unite.
ara in trans 1-4 configuration. The preferred trans 1-4 configuration
of butadiene could be due to the strong electronegativity of the -CN group
of the preceding acrylonitrile unito |
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52 -
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- On the stereochemical mechanism of a-olefin polymerization
- A. ZAMBELLI |
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Summary - Tho study of tho steroochomical mochanisms
of steroospecific polymorizations is complicatod, with respect to micromolecular
organic reactions, by the impossibility of separation and individuaI characterization
of the main and secondary roaction products (i.o., tho differontly arrangod
monomoric units).
Suchi a difficulty may often bo ovorcomo by combining techniquos of isotopic
substitution and spectroscopic analysis. For oxample, in the polymerization
of aolefins it was possible to clarify the mechanism of addition to the
doublo bond and that of storie contral. |
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- Low frequency motions of block copolymers by Neutron Scattering
Spectroscopy - D.A.PEACE&J.W.WHITE |
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Summary - Vibration and diffusion spectra determined
by modium resolution incohorent inelastic noutron scattering spoctroscopy,
LN.S.at,296°K,aroreportodforaserics of a, w dibromoalkane/styreno
or butadiono block copolymors, closely related by molecular structuro. The
LN.S. spoctra gonorally show more distinct features than those for infra.rod
spectra which have beati measurod far the same compounds because of the
amplitude and cros; section weighting of neutron E'cattoring in favour ofhydrogenous
modeRo Thie constitutos a usefuI seloction rulo between modes and alIows
sido group motions, such as methyl torsions, phenyl bonds and torsions,
to be identified. Even at the resolution used the froqueneies of theso modes
show depondonce on the mole cuI al' configuration and structuro. Since hydrogen
scattoring domina tes, the intensities of the modes also rolate to tho number
of hydrogen atoms displaced.
Donsity of states spectra far tho chain modos wero observed in ali cases
and fol' the butadiene copolymors (somo of which DI'e oils at room temperature)
evidence for internal diffusion of sidogroups or fegment!' of the chain
appears from the quasi.elastic scattering.
The frequencies of cyclohoxyI flipping and cyclopentyl roorientation in
polycyclohcxyl and polycyclopontyl methacrylatcs have been found and used
to supporto the association of mechanical relaxation phenomena in the;e
polymers with the!'e motions. |
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- The laser-Raman spectrum of polyethylene terephthalate
- J. DEROUAULT, M. J. GALL, P. J. HENDRA, V. ELLIS, M.E.A. CUDBY & H. A.
WILLIS |
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Summary - The laser-Raman spectra of samples of polyethylone
terephthalate (P.E.T.) of various degrees of crystallinity and various physical
states heve been recorded in the rango 4000-100 cm-l. The influence of crystallinity
on the vibra. tionaI spoctra is discussed from a generaI viewpoint and the
Raman bande of P. K T. which aro sonsitive to crystaIlinity aro describod
and discussod in terms of conformational and/or ordoring changos. Tho ovidence
suggests that intorchange interactions decrease whon the degree of crystaIlinity
increases. Further, three relationships al'(' drawn, which mg,y proyide
a versatile method to assess the crystallinity of films or hulk spocimens
of P.E.T. from the relative intonsities of Raman bi'.nds. |
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- Conformational isomorphism in crystalline polymers - P.
CORRADINI |
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Summary - The occnrrence of phonomena of conformational
isomorphism in crys- talline polymers is discussed. The possiblo cases of
conformational isomorphism cali Ot' clas!'ified on tho basis of two possibilitios:
<1> tho chain atoms may assume in the s,tme crystal, more or less randomly,
different nearly isosteric conformations (e.g., high temper- ature polymorph
of 1.4 trans polybutadieno and of l-4 cis polyisoprene); <2>
the geome. try oftho main chain being fixed, the atoms oftho lateraI groupsmay
assumo in thesamo cryst!Jl, moro or 10ss randomly, difforent conformations
(e.g., isotactic poly-S-3.methy! pentono). The concopt of conformational
isomorphism can be applied alBo to the caso or point a.nd lino dofocts in
polymers, whenovor thoy aro due to different conforma tiolls of portions
of the micromoleculos, tolerated by tho crystaI lattice. |
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- Investigation on the sequence Iength distributions of Iabelled
and of inactive ethyIene-propylene copolymersby pyrolysis and on their chemical
heterogeneity - M. SEEGER, J. EXNER & H.-J. CANTOW (Abstract) |
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- Nuclear magneti cresonance study on the adsorption of poly
(methyl-meth- acryIate) at a solidliquid interface - T. MIYAMOTO & H.-J.
CANTOW (Abstract) |
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- Vibrational spectra of disordered polymers - G. ZERBI (Abstract) |
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II - ROUND TABLE ON 'STUDIES ON POLYMER STRUCTURE BY IR SPECTROSCOPY |
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- Representation and description of configuration and conformation
of molecules - M. PERALDO |
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Summary - ThE' fir'st part oftbis parer is an examination
ofthe convenience of representing the configuration, alwa.ys expJicit by
local and schematized perspectives, quite independent ofany particnlar
conventional reference conformation ofthe molecnle, rather than by projections.
On tbe schematized perspectives, which explicitly and univocally represent
both constitutionandalso configuration independently of conformation, independent and not di8crepant information on loca l conformations may be easily
added. In this way one obtains a schematized, explicit, and univoca I representation
ofthe constitution,
configuration alleI, independentIy, alBo of the conformation of the molecule;
sometimes such a, representi'tion may even advantageously replace the not
schematized perspectives them selves.
The second part is an attempt to tackle frolli a generaI point of
view the probIem of de8cribing modelsand local perspectivas with phrases,
some of which may alBO be the nAna] nomenclature 'formulas', completely
neglecting any type oJ priority rules. It was found that with either
very simp]e steric reference it is possible, easy, and convenient to ]ist
stericalIy non-equivalent partA in the constitutional formula in the arder
they bave in the moI- ecule with respect to one of such two refeI'ences.
By exp]icitly declaring with a conven- ient graphical mark the particular
reference used, which clearly shows that configu- ration has al80 been considered,
the listA thus obtained alBo describe molecule configura- tion 8imply,
univocally, and even visualIy. It is noteworthy that, apart frolli the almost
inevitable choice ofthe reference, it is not necessary to choose names (whose
exact mean- ing must be remembered) in arder to distinguish positions or
sterica,lly not equiva]e.nt partA ofthe molecule. It is simp]y stated that
one is ' first ',the othor is ' second ',etc., in a reference
dil'ection; therefore one ]ists themandjor marks them, as 'first', 'second',
etc., respectivoly, or ano st3tes it.
Finally, a comparison is attemptod with other lmown systems in which priorities
play a more or Iess deci&ive role. |
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- Density by pIane and internaI standard bands in absorption
spectra of poly- mers - M, PERALDO |
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Summary - Literature often reports quantitative Iinoar rElationships
betwoen the composition of polymer &les and tho corresponding I R spectra.
Some of them are Iiable to criticism, perhap& with the exception of narrow
ranges, mainly because they are basod on unfounded assumptions on the indepondonco
of the sample composition oftho intensity ofthe particular a.bsorption band
used as thickness ' internaI standard '. The generaI featurc of the problem
wjJl be examined alleI, above all, will be evidenced the convenience a s
well as the case of replacing the method of intorna] standard, or at least
of its adjustment, by the bidimensionai density method (or density by piane,
i.e. tho ratio between the, weight and the cross section of the sample),
The conven- ience and case of replacing the t.hickness and density measurements
on polymer filmA wjlJ be evidenced t.oo, Moreover, by measuring the density
by pIane instead of tho t.hiclmess and of the density, the common relationships
between absorbance and absorptivity become even simpler and tho unit of
absorptivity appaltI' more obvious. |
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- Spectrosoopic studies on aliphatic polyesters - K. HOLLAND-MORITZ
& D. O. HUMMEL |
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Summary - Infrared and Raman spectra as well as electcon diffraction
patterns of a number of Dliphat.ic polyesters (PE) in the crystalline and
amorphous states bave been measured. In most of the CD ses Raman
lines and infrared bands of a PE do not coincide. Selection rules based
on group theory suggest that the repeating unit of these PE possesses a
centre of symmetry. Regarding different simple chain conformations and sym.
metry, only planar structures would fulfil this prerequisite. Presently,
the onlyexcep- tiGli is PE-2,4, where far almost, alI infrared bands a Raman
line of the samo frequency cali be found. This supports the X-ray results
of FULLER snd FROSH.
A semiempirical method was used far the assignment of the coupled bending
(1500 . . .140& cm-l), wagging (1400. . .1200 cm-l) and rocking vibrations
(720. . .910 cm-l) oi' the methylene chains in crysta:lline PE as well as
far the infiuence of the adjacent groups. |
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- An infrared study of the regularity bands of 1,4 trans
polybutadiene - F. CIAMPELLI&C.ToSI |
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Summary - In arder to obtain a deepor knowledge of thenature
of tho infrared regularity bands of 1,4 trans polybutadione, the
spectra of this polymer, of 1,4 trans polybutadiene l,4-d., and of
a series oftheir copolymers bave been examined. The [J.bsorptivities of
some oi" such bands were correlated with the distribution functions oi"
monomer unit.s in sequences of various lengths, and an approximate evaluation
was made of the least number of consecutive monomor units that allows their
detection. |
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III ROUND TABLE ON 'NMR SPECTROSCOPY OF POLYMERS'. |
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- Study of sequence length distribution of polyamethylstyrene
and its copolymers with butadiene by 220 MHz proton resonance spectroscopy
- H.-J. CANTOW, K.-F. ELGERT, E. SEILER & G. PUSCRENDORF (Abstract) |
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- Conformation ofpolyethylene by NMR - L. ZETTA & G. GATTI
(Abstract) |
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- Nuclear magnetic resonance spectra of isobutylene-chlorotrifluoroethylene
copolymers -L. CAVALLI (Abstract) |
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- NMR spectra of head-to-tail polypropylenes - M. PERALDO
(Abstract) |
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- Conformation of Liduronic acid moieties in chondroitin B
and in heparin - A. S. PERLIN, B. CASU, G. R. SANDERSON & J. TSE (Abstract) |
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IV - MEETING ON PROBLEMS OF COPOLYMER STATISTICS |
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- Copolymérisation radicalaire: effets pénultièmes de réaotivité
et distribution théorique des séquences - J. GUILLOT |
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Summary - As tho properties of a copolymer depend on its microstructure,
the influence of remote units on the reactivity of the polymeric radicals
and the consecutive modifications on both the kimtics and the sequence distribution
are examined.
Kinetical schemes and equations of copoJymerization are given according
to those penultima te effects. As a l'emark about a recent equation of G.E.
RAM, it is shown that the postulate of 'Sequence Reversibility' is no more
valid when antepenuJtimate effects occur. |
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Methods aro alBo given far the determining of reactivity ratios,
taking into account ali these offects. Calcnlations of the. theoretical
distribution of the comonomer unitA, performed on a computer - remote unitA
0ffoct<.; and conversion being considered - aro briefly discussed with some
experimental resnJts. In eoneJusion, some explana tions of such penultima
te effects aro given and the interest of the knowledge of the truo kinetical
mechanisms is elucidated. |
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- Statistical quantities in blended copolymers - T. SIMONAZZI,
F. SEVINI & C. TOSI |
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Summary - The mechEmical mixing of two copolymers of the SRme
monomor yields a copolymer in which ' ext3nsive ' quantities, such as the
eomposition, tho amount of soquences containing a given numbBr ofmonomer
units, the amount ofbonds between lik2 or unlike monomer units afe the weighed
averago of those of tho starting copolymers, whi]o othor quantities, d9rived
from tbc former on the basis of eertain mathematical rela- tionships, afe
related to the corresponding guantities of the starting copolymers in a
muchmore involved way. This is the case far thoproduct of reactivity ratios,
which measures the so-colled 'soquontial homogenoity' of copolymers. It
may bo proved that different ' apparent ' valnes of the product of reactivity
ratios of the blend are found, depemding on the quantity ehar(wteristie
far :oequenee distribution whieh is oxperirmmtally measured and utilized
for calculation.
In this pa,per we study the behaviour of blends of othyleno-propylene eopolymers.
Their apparent produet of reactivity ratios is determined through the ratio
between the fraetions of propylone-propylene and propylone-ethylene bonds,
whieh, in tu l'n, is cva.luated from thc methyl roeking bandA in the infrared
speetra. |
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- Improved treatment of copolymer randomness - C. TOSI |
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Summary - In the first parto of the paper, tbe studies recently
made on the randomness of copolymers are reviewed and the properties of
informa,tionalentropy, whieh expresses this quantity in mathematieal terms,
aro diseussed; partieular emphasis is focnsed on the possibility of extending
the concerto of informational entropy to the statistics of conformations
in biopolymers.
In the Acconci parto, the nature ofinformational cntropy is more deeply
inquired iuta and its behaviour with rcspect to the increase in information
obtaincd by carrying out successive experimental measurements on the copo]ymer
is investigated. It is shown that the maximum value taken on by informational
entropy corresponds to a geometrical distribntion of the fractions of sequ9nces
contairling an increasing number of monomer units, in full a.na logy with
the distribution of a system of physical partic!s aver the energy lovels;
this permits to express tho copolymerization oquation by a variational principio
on the informational entropy of the resulting copolymer. It is alg~ shown
that, provided that copolym(;rization obeys a Markoifian statistics, the
knowledge of the composition and of one parameter characteristic of sequence
distribntion is enough to define the value far informational entropy, ane!
the gain of information obtained by performing further measnrements on the
copolymcr is only apparent. |
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Some remarks on the free radicals steady state assumption
in the copolymerization theory - P. F. MARCONI |
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Summary - By applying the continuous timo Mark)V chains mathematics
to the stochastic evolution of Eroe radicals in the copolymcriza tion, it
is proved that the assumption of a very long polymeric chain and Markovian
propagation model involves necessarily the stoody state of each radical
type, which hypothesis up to day has been considered of dubions significance. |
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- Sequence statistics during polymer analogous reactions by
NMR data and Monte Carlo simulation - E. KLESPER, W. GRONSKI, V. BARTH &
A. J OHNSEN (Abstract) , |
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Alphabeticallist aJ Authars . |
