Mechanical Properties and Orientation of Atactic Poly(methyl methacrylate): Sub-Tg Annealing and Stereocomplex Formation

Thermal decomposition study of poly(methyl methacrylate)/carbon nanofiller composites

“…The melting of the stereocomplexes was indeed reported in several papers as an endothermic process by DSC at ∼200°C see, e.g. Reference 38. In our study this endotherm is observed on first heating but disappears after solvent removal (see thick vertical arrow in Fig.…”

Electrospinning Physical Gels: The Case of Stereocomplex PMMA

“…25 In our case, the comparison with a-PMMA is all the more relevant, as the only difference between the a-PMMA solution and the stereocomplex PMMA solution is the occurrence of physical gelation. Although stereocomplex-like interactions in atactic PMMA solutions in strongly complexing solvents (DMF is a strongly complexing solvent) have been detected by spectroscopic methods (NMR, FTIR) [26][27][28] and DSC, 28,29 the observation of physical gelation was not reported. Most likely the length of the isoatactic and syndiotactic sequences in atactic PMMA polymers was not sufficient to facilitate the formation of long helices and subsequent packing into bundles and gelation.…”

Stereocomplexation of Stereoregular Poly(methyl methacrylate) in Thin Film at Gold Surface

“…On the contrary, great intensity changes can be identified for several bands of the TIR and RAIR spectra cast from acetone solution, especially those at 1450, 1273, and 1257 cm -1 related to the ester group and 860 cm -1 corresponding to the main-chain CH 2 rocking vibrations (see Figure B). , These intensity changes are mainly attributed to dichroic effect and indicate some ordered arrangement of molecular chains in thin film. It should be pointed out that (i) acetone is a strong-complexing solvent for inducing stereocomplexation of PMMAs, while chloroform is attested to be a noncomplexing solvent, ,, (ii) the stereocomplexation of PMMAs was triggered mainly by dipole−dipole interaction of i- and s-ester groups, , (iii) the changes in most bands all correspond to the energetically most favorable conformation of the PMMA ester group which are always related to the formation of stereocomplex, , and (iv) the band at 860 cm -1 , a character band for the formation of PMMA stereocomplex, does not appear in TIR and RAIR spectra of the films cast from chloroform, while it appears clearly in those cast from acetone. Taking all those into account, the ordered arrangement of PMMAs may originate from complexation of stereoregular PMMAs.…”