Optimization of monomer content and degree of linearity in lithographically interesting novolac copolymers using NMR spectroscopy

Quantitation of microstructure of novolac resins: Development of improved one‐ and two‐dimensional NMR methodologies

“…Thus, the intensities of the carbon atoms (even of the same type: primary, secondary, or tertiary) are not totally dependable. 10 In this article we propose an improved method of calculating the U n value from the intensities of the fully relaxed 1 H-NMR spectra using two-dimensional heteronuclear single quantum correlation (HSQC), double quantum filtered correlation spectroscopy (DQF-COSY), and total correlation spectroscopy (TOCSY) experiments. The natural abundance of hydrogen nuclei is highest compared to the other NMR active nuclei, and thus for quantitative estimation from NMR spectroscopy the 1 H-NMR intensities would be much more dependable.…”

“…The degree of linearity (U 4 ) of this novolac copolymer was also calculated using the inverse gated broadband protondecoupled quantitative 13 C-NMR spectrum. 10 The problem of the nuclear Overhauser effect and the consequent unequal polarization transfer from corresponding hydrogen to carbon atoms was obviated by using the inverse gated pulse sequence. Broadband decoupling enables us to obtain heteronuclear decoupling along with homonuclear decoupling.…”

Quantitative estimation of the degree of derivatization: an alternative methodology using 1‐D and 2‐D NMR experiments

“…Inverse-gated 1 H-decoupled 13 C NMR spectra have been used for the quantitative estimation of the degree of protection. 8 -10 For precise quantitation based on the NMR signals, two important parameters are (i) the nuclear Overhauser effect (NOE) and (ii) relaxation time.…”

“…8 -10 For precise quantitation based on the NMR signals, two important parameters are (i) the nuclear Overhauser effect (NOE) and (ii) relaxation time. Although the decoupling of 1 H interaction while recording 13 C signals allows one to obtain a simplified spectrum, NOE must also be taken into account for quantitation purposes. The inverse-gated decoupling technique successfully removes NOE differences from the 13 C NMR spectrum.…”

“…12 However, when the monomers become incorporated in the polymer, carbon atoms in the same chemical but different microstructural environments are not associated with the same J values, owing to the effects of high polydispersivity I p . A much longer pulse delay along with heteronuclear decoupling (broadband decoupling) therefore required for recording the fully relaxed 13 C NMR spectrum. 13 In this paper, we describe a method to assess the percentage of t-BOC incorporated using the fully relaxed 1 H NMR spectrum with the help of 13 C NMR, 2-D HSQC and TOCSY techniques.…”