The solution and solid-state thermochromism of unsymmetrically substituted polysilanes

Optical and Electrochemical Transducers Based on Functionalized Conjugated Polymers

“…[66±68] More precisely, it has been suggested that these optical effects are driven by a delicate balance between repulsive steric interactions and attractive interchain (or intrachain, due to chain folding) interactions; the latter being necessary to get a planar conformation in the case of thermochromic polythiophenes. [12,39] On the other hand, as observed with poly(3,3¢-dialkyl-2,2¢bithiophene)s (Fig. These assumptions are in agreement with Fourier transform infrared spectroscopy (FTIR) measurements, which have revealed that some disorder is created in the side chains and the main chain upon heating.…”

Optical and Electrochemical Transducers Based on Functionalized Conjugated Polymers

“…These assumptions are in agreement with Fourier transform infrared spectroscopy (FTIR) measurements, which have revealed that some disorder is created in the side-chains and the main chain upon heating [16][17][18][19]. Similar mechanisms can be proposed for substituted polydiacetylenes and polysilanes [12,39]. On the other hand, as observed with poly(3,3'-dialkyl-2,2'-bithiophene)s ( possible by the adequate steric hindrance created by the methyl group at the 4-position, which forces the formation of a nonplanar conformation when highly conjugated (coplanar) polythiophene assemblies are disrupted [66][67][68].…”

“…This intriguing effect has been extensively studied and has led to the development of various thermochromic polythiophene [4,5,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], polysilane [30][31][32][33][34][35][36][37][38][39][40][41], and polydiacetylene [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] derivatives (Figure 2.1). As an example of thermochromism reported for some neutral conjugated polymers, Figure 2.2 shows the temperature-dependent UV-vis spectrum of sodium poly[2-(4-methyl-3-thienyloxy)ethanesulfonate] in...…”

Chain dimensions and intermolecular interactions of polysilanes bearing alkyl side groups over the UV thermochromic temperature

“…Those are below the theta temperature estimated for PSi-3-84k, clearly indicating the formation of aggregation. Similar behavior were found for the other high molar mass poly(dialkylsilane)s[14,38]. Since the appropriate Guinier ranges are not available for the data, we compared the data with the particle scattering function of rigid…”

“…Miller, Shukla, and their coworkers [14,38] found that chain dimensions for some poly(dialkylsilane)s with the weight-average molar mass Mw of ~10 6 g mol 1 are irrespective of temperature but significant aggregates were observed at or below the transition region by light and neutron scattering measurements, suggesting attractive intermolecular interactions at low temperatures.…”