Editing Tacticity (section)

==Techniques for measuring tacticity==

Tacticity may be measured directly using [[proton]] or [[carbon-13]] [[NMR]].  This technique enables quantification of the tacticity distribution by comparison of peak areas or integral ranges corresponding to known diads (r, m), triads (mm, rm+mr, rr) and/or higher order ''n''-ads, depending on spectral resolution.  In cases of limited resolution, stochastic methods such as [[Bernoulli process|Bernoullian]] or [[Markov chain|Markovian analysis]] may also be used to fit the distribution and predict higher ''n''-ads and calculate the isotacticity of the polymer to the desired level.<ref>{{cite journal|doi=10.1021/ma60057a006|title=Carbon-13 NMR Determination of Pentad Tacticity of Poly(vinyl alcohol)|year=1977|last1=Wu|first1=Ting Kai|last2=Sheer|first2=M. Lana|journal=Macromolecules|volume=10|pages=529|issue=3|bibcode = 1977MaMol..10..529W }}</ref>

Other techniques sensitive to tacticity include [[x-ray powder diffraction]], [[secondary ion mass spectrometry]] (SIMS),<ref>{{cite journal|doi=10.1002/(SICI)1096-9918(199701)25:1<41::AID-SIA211>3.0.CO;2-T|title=Influence of Tacticity on Polymer Surfaces Studiedby ToF-SIMS|year=1997|last1=Vanden Eynde|first1=X.|last2=Weng|first2=L. T.|last3=Bertrand|first3=P.|journal=Surface and Interface Analysis|volume=25|pages=41–45}}</ref> vibrational spectroscopy (FTIR)<ref>{{cite journal|doi=10.1021/ma00207a013|title=Normal-mode analysis of infrared and Raman spectra of crystalline isotactic poly(methyl methacrylate)|year=1990|last1=Dybal|first1=J.|last2=Krimm|first2=S.|journal=Macromolecules|volume=23|pages=1301|issue=5|bibcode = 1990MaMol..23.1301D }}</ref> and especially two-dimensional techniques.<ref>{{cite journal|doi=10.1021/ma00149a011|title=Observation of the stereochemical configuration of poly(methyl methacrylate) by proton two-dimensional J-correlated and NOE-correlated NMR spectroscopy|year=1985|last1=Schilling|first1=Frederic C.|last2=Bovey|first2=Frank A.|last3=Bruch|first3=Martha D.|last4=Kozlowski|first4=Sharon A.|journal=Macromolecules|volume=18|pages=1418|issue=7|bibcode = 1985MaMol..18.1418S }}</ref>  Tacticity may also be inferred by measuring another physical property, such as melting temperature, when the relationship between tacticity and that property is well-established.<ref>{{cite journal|doi=10.1021/ma8014992|title=Pressure Dependence of the Glass Transition in Atactic and Isotactic Polypropylene|year=2008|last1=Gitsas|first1=A.|last2=Floudas|first2=G.|journal=Macromolecules|volume=41|pages=9423|issue=23|bibcode = 2008MaMol..41.9423G }}</ref>