Acrylonitrile-ethylmethacrylate

4 Acrylonitrile and Methacrylonitrile Containing Copolymers 7.4.1 Acrylonitrile-ethylmethacrylate 

Kapur and Brar [179] prepared acrylonitrile-ethyl methacrylate (A/E) copolymers of different monomer concentrations in bulk by free radical initiation. Copolymer composition was determined by nitrogen analysis and the comonomer reactivity ratios were determined by the method of Kelen-Tiidos. C-NMR spectra of several A/E copolymers are discussed in terms of their triad monomer sequence and cotacticity. Terminal and penultimate reactivity ratios were calculated using the observed monomer triad sequence distribution determined from C-NMR spectroscopy for individual samples. Triad sequence distribution was used to calculate dyad concentrations, probability parameters, number average sequence lengths, and the comonomer mole fractions in the copolymers. The configurational sequence distributions in terms of all the 10 A-centred and 10 E-centred triad cotactic sequences have been determined and found to be in excellent agreement with those obtained using various cotactic probability parameters. 

The populations of all the 20 A- and E-centred tactic monomer sequence triads mentioned previously, in the A/E copolymer samples calculated using the probability parameters and those obtained from C-NMR spectra are given in Table 7.13. The observed and the calculated tactic triad sequence populations are in fairly good agreement. The - EE - sequence in a EEE and EEA triad has a slightly different value of P. Similarly the -AA sequence in AAA and AAE triad has a different value of P The cotacticity of -EA- sequence is random. The tacticities or -EE- and the -AA-diads in the copolymer are identical to tacticities in homopolymers. The cotacticity of the -AE- diad is also random and indicates that E and S monomer unit do not interact sterically during the copolymerisation. 

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C to 31°C. Another intelligent gel invented by Sonja Krause and Katherine Bohon at the Rensselaer Polytechnic Institute consists of poly(dimethylsiloxane) and poly(ethylene oxide). This material demonstrates the ability to pulsate back and forth between its expanded and contracted form in less than a millisecond when a small electrical potential is applied to it. Among the most popular materials used to make smart gels are the polymers poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA), poly(acrylonitrile) (PAN), poly(2-hydroxy-ethylmethacrylate), and poly(2-hydroxypropylmethacrylate). 

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