Thermodynamic properties of liquid-crystalline carbosilane dendrimers of the second and the fourth generation with methoxyphenylbenzoate terminal groups

Thermochimica Acta 614 (2015) 226–231

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Thermodynamic properties of liquid-crystalline carbosilane dendrimers of the second and the fourth generation with methoxyphenylbenzoate terminal groups N.N. Smirnovaa , Ya. S. Samosudovaa , A.V. Markina,* , V.P. Shibaevb , N.I. Boikob a b

Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/5, 603950 Nizhny Novgorod, Russian Federation Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation

A R T I C L E I N F O

A B S T R A C T

Article history: Received 9 December 2014 Received in revised form 8 June 2015 Accepted 19 June 2015 Available online 27 June 2015

In the present work temperature dependences of heat capacity of liquid-crystalline carbosilane dendrimers with terminal methoxyphenylbenzoate groups of the second and the fourth generations have been determined in the range from 6 to 370 K by the precision adiabatic vacuum calorimetry. In the above temperature range the phase transformations have been detected and their thermodynamic characteristics have been determined and analyzed. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity C op ðTÞ, enthalpy Ho ðTÞ  Ho ð0Þ, entropy So ðTÞ  So ð0Þ

Keywords: Liquid-crystalline carbosilane dendrimers Generation Methoxyphenylbenzoate terminal groups Adiabatic vacuum calorimetry Heat capacity Thermodynamic functions

and Gibbs energy Go ðTÞ  Ho ð0Þ, for the range from T ! 0 to 370 K. The standard entropies of formation of dendrimers in liquid-crystalline state at T = 298.15 K and the standard entropies of hypothetic synthesis at the same temperature were estimated. It was shown that thermodynamic properties dendrimers under study do not depend on generation number and are defined by nature of terminal groups. ã 2015 Elsevier B.V. All rights reserved.

1. Introduction Dendrimers are specially class of high-molecular compounds whose molecules are highly ordered spatially hyperbranched topologically completely acyclic compositions with structure of continuously branching tree [1,2]. Liquid-crystalline (LC) dendrimers, which molecules combine structural units (commonly referred to as mesogenic groups) capable to impart the liquidcrystalline properties with amorphous dendritic architecture have attracted progressively growing attention of researchers engaged in the chemistry and physics of liquid crystals, physical chemistry of polymers, and supramolecular chemistry [3–8]. This interest is related to the search for new materials for nanotechnology and electronics which need molecules – particles with a size of several nanometers – that are capable of ordering and changing their properties under application of external fields. Carbosilane liquid-crystalline dendrimers hold a particular position among a wide scope of studied dendrimers. This is connected with their kinetic and thermodynamic stability and vast possibilities to change their dendritic architecture via specific reactions typical of silicon [3–8].

* Corresponding author. Fax: +7 831 462 31 55. E-mail address: [email protected] (A.V. Markin). http://dx.doi.org/10.1016/j.tca.2015.06.024 0040-6031/ ã 2015 Elsevier B.V. All rights reserved.

The structure and phase state of different generation LC carbosilane dendrimers with various types of terminal groups are examined in detail at the present time [9–12]. However the data on thermodynamic properties of liquid-crystalline dendrimers are absent. In this connection the aim of this study is calorimetric investigation on the temperature dependence of heat capacity of LC carbosilane dendrimers of the second and the fourth generations with terminal methoxyphenylbenzoate groups G-2 (Und-MPhB)16 and G-4(Und-MPhB)64 in the range 6–370 K, detection of possible phase transformations and determination of their thermodynamic characteristics, calculation thermodynamic functions C op ðTÞ, H (T)  H (0), S (T)  S (0) and G (T)  H (0) over the temperature range from T ! 0 to 370 K and standard entropies of formation of dendrimers in liquid-crystalline state at T = 298.15 K and the revealing of dependences of dendrimers thermodynamic functions on their composition. 2. Experimental 2.1. Sample The scheme of synthesis and structure of liquid-crystalline carbosilane dendrimers of the second and the fourth generations with terminal methoxythenyl benzoate groups are shown on Fig. 1.

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Fig. 1. The scheme of synthesis and structure of liquid-crystalline carbosilane dendrimers of second and fourth generations with terminal methoxyphenylbenzoate groups.

The samples of dendrimers under study were synthesized in Moscow State University at the Laboratory of Polymers Chemical Transformations of High-molecular Compounds by the method described in detailed elsewhere [13]. Obtained dendrimer samples were cleaned by the methods of preparative gel permeation chromatography (a «KNAUER» device, column Waters 8  300 on ultrasilicagel with pore size (dimension) 103 Å, THF as an eluent, detector is the refractometer Waters R-410). Purity and individuality of studied dendrimers were

approved by GPC analysis and NMR 1H-spectroscopy (a Bruker WP-200 and WP-250 spectrometer in CCl4 and CDCl3 solutions). NMR 1H data for G-2(Und-MPhB)16: (CCl4, 200 MHz): d = 0.1 (s, 36H), 0.2 (s, 192H), 0.7 (m, 112H), 1.4 (m, 268H), 1.8 (m, 32H), 2.6 (m, 32H), 3.9 (t, 48H), 7.0 (d, 32H), 7.2 (d, 32H), 7.3 (d, 32H), 8.3 (d, 32H). NMR 1H data for G-4(Und-MPhB)64: (CDCl3, 250 MHz): d = 0.08 (s, 180H), 0.03 (s, 768H), 0.54 (m, 624H), 1.27 (m, 268H), 1.72 (m, 128H), 2.54 (m, 128H), d = 3.78 (t, 196H), 6.89 (d, 28H), 7.08 (d, 128H), 7.18 (d, 128H), 8.18 (d, 128H).

Table 1 Samples information. Sample

Source

State

Mole fraction purity

Purification and analysis methods

G-2(Und-MPhB)16

Present work

Liquid-crystalline

0.99

G-4(Und-MPhB)64

Present work

Liquid-crystalline

0.99

GPCa NMR 1H-spectroscopy, X-ray diffraction analysis GPCa NMR 1H-spectroscopy, X-ray diffraction analysis

a

Gel permeation chromatography.

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The polarising microscopic investigations were performed using a Mettler FP-800 central processor equipped with a hot stage Mettler FP-82 and control unit in conjunction with a Lomo R-112 polarising microscope. X-ray difraction measurements were made using CuKa radiation (l = 1.542 Å) from 1.5 kW sealed tube. Monodispersity of compounds was confirmed by GPC analysis. The information for the studied dendrimers is listed in Table 1 as phase behavior and structure was published in detail in Ref. [13].

observed the fusion of liquid crystals crI with the formation of isotropic liquid in the temperature range from 345 to 355 K (the range LMNO, curve 2 and the plot IJK, curve 1, Fig. 2). Otherwise the temperature dependences of heat capacity of compounds under consideration had not any features. Heat capacity smoothly increased with the temperature rise and following relation C op [G-2(Und-MPhB)16] < C op [G-4(Und-MPhB)64] (Fig. 2) takes place always.

2.2. Apparatus and measurement procedure

3.2. Thermodynamic characteristics of phase transformations

To measure the heat capacity C op of the tested substances in the range from 6 to 370 K a BKT-3.0 automatic precision adiabatic vacuum calorimeter with discrete heating was used. The calorimeter design and the operation procedure were described earlier [14,15]. The calorimeter was tested by measuring the heat capacity of special-purity copper (OSCH) and reference samples of synthetic corundum and K-2 benzoic acid. The analysis of the results showed that an uncertainty of measurements of the heat capacity of the

The thermodynamic characteristics of devitrification and glassy state dendrimers under study are listed in Table 2. The glass transition temperature T og was determined by the Alford and Dole method [16–18] from the inflection of the plot of S (T) = f(T). The devitrification interval and an increase in the heat capacity on devitrification were determined graphically. The configuration entropy was calculated by Eq. (1), which was suggested in work [19]:

substances at helium temperatures was within to 2  102 C p , with rising temperature up to 40 K it decreased down to 0:5  103 C op and was equal to 2  103 C op at T > 40 K. Temperatures of phase transformations can be determined with standard uncertainty u(T) = 0.02 K. 3. Results and discussion 3.1. Heat capacity The tested substances under conditions of our apparatus were undercooled and then vitrified on cooling from room temperature to the temperature of the measurement onset (6 K) at the average rate of 0.01 K/s. On subsequent heating under the measurement of heat capacity it was observed the devitrification of dendrimers amorphous part (the region BC on Fig. 2) over the range from 230 to 275 K. The crystalline part of the samples underwent physical transformations since 280 K. It was detected the transition of semicrystalline state crIII to crystals crII (the range CFGH, curve 2 on Fig. 2), which formed liquid crystals crI (the range HGIK, curve 2 on Fig. 2) for G-4(Und-MPhB)64. Liquid-crystalline state was formed less complicated for the dendrimer of the second generation (the plot CFGH, curve 1 on Fig. 2) in conditions of thermodynamic equilibrium experiment. For all dendrimers it was

Fig. 2. Temperature dependence of the heat capacity of G-2(Und-MPhB)16 (curve 1) and G-4(Und-MPhB)64 (curve 2).

Soconf ¼ DC op ðT og Þln

T og

(1)

T o2

where is T o2 —Kauzmann temperature [20], usual value of the ratio T og =T o2 for monomeric and polymeric glass is equal to (1.29  0.14) [19,21]. It appears that this relation is correctly for all dendrimers under consideration. It was shown in papers [19,22] that the numerical value Soconf is close to the value So ð0Þ and configuration entropy may be used to estimation absolute values of entropies glassy substances whereas So ð0Þ  Soconf [23].   The increase in the heat capacity on devitrification DC op T og is associated with vibration excitation of atoms and atomic groups capable to substantive movements. Its additive contribution per «bead» is about 11 J K1 mol1 [24]. This makes possible to define   their quantity k ¼ DC 0p T og =11 in each dendrimer under study. It is interesting that the quantity of excited atomic groups goes up 2.5 times from second to fourth generation. It is likely that the same glass transition temperature value is caused by vibration excitation of identical by composition and nature atomic groups and the growth of k occurs at the expense of increasing free volume in internal spheres of fourth generation dendrimer. Parameters of phase transformations, including in liquidcrystalline state, are listed in Table 3. The transition crIII @ crII is connected with formation of liquid-crystalline state for G-4 (Und-MPhB)64, which is undergoing the rearrangement of crystals crII to crI on further heating. Where is no such transformation for the second dendrimer and the liquid-crystalline state formation is designated as a transition crII @ crI. When subsequent heating all dendrimers were melting with formation of isotropic liquid l. The phase behavior and phase transition temperatures of the dendrimers previously were determined by polarizing optical microscope (POM) with LOMO P-112 polarizing microscope equipped by Mettler TA-400 heating stage [13]. The transition temperatures have been taken the temperatures, responding the maximal apparent heat capacity values in transition intervals which are given below: Dendrimer

Temperature intervals of transformations crIII @ crII

crII @ crI

crI @ l

G-2(Und-MPhB)16 G-4(Und-MPhB)64

– 277.49–289.63

274.60–295.02 292.01–298.99

338.90–364.70 345.83–358.55

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Table 2 Glass transition and glassy state characteristics of G-2(Und-MPhB)16 and G-4(Und-MPhB)64 liquid-crystalline carbosilane dendrimers with methoxyphenylbenzoate terminal groups at pressure p = 0.1 MPa.a Dendrimer

Gross-formulae

E560=892Si45?96 E2288=3676Si189?384

G-2(Und-MPhB)16 G-4(Und-MPhB)64 a

M (g mol1)

T og þ 1

10424 42634

254 258



DC op T og

(K)

(kJ K

1



mol

1

)

3.65  0.04 15.7  0.2

Soconf (J K1 mol1)

So ð0Þ (J K1 mol1)

929  10 3998  40

930 4000

Standard uncertainty u is u(p) = 10 kPa; reported uncertainties correspond to the combined expanded uncertainties for 0.95 level of confidence (k  2).

Table 3 Thermodynamic characteristics of phase transformations for studied liquid-crystalline carbosilane dendrimers samples at pressure p = 0.1 MPa.a Dendrimer

Transitions crIII @ crII T otr

crII @ crI

Dtr H (kJ mol ) o

(K) G-2(Und-MPhB)16 G-4(Und-MPhB)64 a

– 287.2  0.2

– 412  4

1

Dtr S

o

(J K1 mol1) – 1433  15

crI @ l

Dtr H

T otr

Dtr S

(J K1 mol1)

T ofus (K)

Dfus Ho

Dfus So

581.2  5.8 373.4  3.8

351.1  0.1 351.2  0.1

69.76  0.71 174.2  1.8

198.7  2.0 496.1  5.0

o

o

(K)

(kJ mol1)

287.2  0.2 294.6  0.2

166.8  1.8 110.2  1.0

(kJ mol1)

(J K1 mol1)

Standard uncertainty u is u(p) = 10 kPa; reported uncertainties correspond to the combined expanded uncertainties for 0.95 level of confidence (k  2).

Phase transition enthalpies have been calculated as areas, which are limited responding figures, e.g. for the transition crI @ l is IJKI for G-2(Und-MPhB)16 (Fig. 2). Phase transition entropies were evaluated by the second law of thermodynamics with using enthalpies and temperatures values. Also dendrimer samples under consideration are melting at the same temperature (Table 2) irrespective of generation number. It should be noted that phase transitions thermodynamic characteristics in liquid-crystalline state were reproduced by repeated heating and cooling. The dendrimer samples form inclined type smectic crystals [25] in liquid-crystalline state. The structure of dendrimers was confirmed by means of X-ray diffraction investigations. WAXS results showed one diffuse peak with intermesogenic distance about 5 Å, that slightly raises with the increase of the generation number (D = 4.89 Å for G-2(Und-MPhB)16 and D = 4.94 Å for G-4 (Und-MPhB)64). SAXS measurements revealed two sharp reflections being first and second order from the layer spacing (d = 42.7 Å and 46.6 Å, respectively). They also increase with the growth of the generation number. These results suggest the existence of orthogonal disordered smectic A mesophase for compounds in question. As a result, the dendrimers possess lamellar structure where the layers of mesogenic groups alternate with the layers of dendritic cores. 3.3. Standard thermodynamic functions To calculate the standard thermodynamic functions of G-2 (Und-MPhB)16 and G-4(Und-MPhB)64 (Tables 4 and 5) their C op values were extrapolated from measurement onset (6 K) based on Debye’s heat capacity function:   QD (2) ; C op ¼ nD T where D is the function of Debye’s heat capacity, n and QD are specially selected parameters. The calculation of Ho ðTÞ  Ho ð0Þ and So ðTÞ  So ð0Þ was executed by the integration of C op ¼ f ðTÞ and C op ¼ f ðlnTÞ curves, respectively, and the Gibbs energy Go ðTÞ  Ho ð0Þ was calculated with Gibbs– Helmholtz equation from the enthalpies and entropies at the corresponding temperatures.

Table 4 The thermodynamic functions of liquid-crystalline carbosilane dendrimer of the second generation with methoxyphenylbenzoate terminal groups G-2(UndMPhB)16 (M = 10,424 g mol1) at pressure p = 0.1 MPa.a H ðTÞ  H ð0Þ

S ðTÞ  S ð0Þ

(kJ mol1)

(J K1 mol1)

   Go ðTÞ  Ho ð0Þ (kJ mol1)

0.0583 0.798 2.79 6.392 11.98 19.62 40.77 105.9 197.9 313.0 448.5 602.7 775.8 969.1 1183 1415 1669 1971 2345 2481

15.5 110 267 472.0 719.7 997.2 1600 2900 4215 5495 6728 7914 9069 10,206 11,330 12,437 13,540 14,747 16,133 16,612

0.0195 0.297 1.22 3.049 6.012 10.29 23.25 68.09 139.3 236.5 358.8 505.3 675.1 867.9 1083 1321 1581 1863 2172 2287

Liquid-crystalline state crI 287.2b 19.50 2648 290b 19.50 2707 298.15 19.60 2866 320 20.48 3300 340 21.89 3724 350b 22.15 3944 351.1b 22.15 3967

17,194 17,396 17,938 19,344 20,627 21,267 21,331

2287 2338 2482 2890 3289 3499 3520

Liquid state l 351.1b 22.15 370 22.31

21,530 22,702

3520 3941

T (K)

C op ðTÞ (kJ K1 mol1)

Semicrystalline state crII 5 0.0463 10 0.262 15 0.546 20 0.9111 25 1.321 30 1.735 40 2.482 60 4.001 80 5.204 100 6.284 120 7.252 140 8.172 160 9.150 180 10.18 200 11.16 220 12.08 240 13.47 260 17.43 280b 19.37 287.2b 19.50

4037 4459

a Standard uncertainty of temperature u(T) = 0.01 K. Eombined expanded relative uncertainties for the heat capacity Uc ðC op Þ are 0.02, 0.005 and 0.002; the combined   expanded relative uncertainties Uc;r H ðTÞ  H ð0Þ are 0.022, 0.007 and 0.005;     Uc;r S ðTÞ  S ð0Þ are 0.023, 0.008 and 0.006; Uc;r G ðTÞ  H ð0Þ are 0.03, 0.01 and 0.009 in the ranges 6 K  T  15 K, 15 K  T  40, and, 40 K  T  370 K, respectively for 0.95 level of confidence (k  2). b Extrapolated.

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Table 5 The thermodynamic functions of liquid-crystalline carbosilane dendrimer of the fourth generation with methoxyphenylbenzoate terminal groups G-4(UndMPhB)64 (M = 42,634 g mol1) at pressure p = 0.1 MPa.a C op ðTÞ

H ðTÞ  H ð0Þ

S ðTÞ  S ð0Þ

   Go ðTÞ  Ho ð0Þ

(kJ K1 mol1)

(kJ mol1)

(J K1 mol1)

(kJ mol1)

0.239 3.42 12.4 28.45 52.12 83.63 171.6 435 806 1281 1843 2482 3202 4000 4882 5849 6903 8127 9703 10,321

63.9 463 1175 2088 3138 4283 6792 12,058 17,361 22,642 27,752 32,667 37,467 42,162 46,808 51,409 55,991 60,882 66,718 68,894

0.0799 1.21 5.23 13.31 26.34 44.87 100.1 288.4 582.6 982.8 1487 2092 2793 3589 4479 5461 6535 7702 8978 9482

Liquid-crystalline state crII 287.2b 82.97 10,733 294.6b 82.97 11,329

70,327 72,374

9482 9994

Liquid-crystalline state crI 294.6b 82.97 11,439 298.15 82.97 11,731 320 83.31 13,544 340 84.69 15,224 350b 85.17 16,074 b 351.2 85.23 16,176

72,748 73,736 79,604 84,696 87,158 87,450

9994 10,253 11,929 13,572 14,432 14,536

Liquid state l 351.2b 85.23 360 85.67 370 86.65

87,946 90,060 92,419

14,536 15,320 16,232

T (K)

Semicrystalline state crIII 5 0.191 10 1.18 15 2.46 20 4.032 25 5.458 7.180 30 40 10.35 60 15.91 80 21.16 100 26.12 120 29.95 140 34.00 37.90 160 180 42.04 200 46.14 220 50.10 240 55.45 260 70.45 280b 82.96 b 287.2 82.97

16,350 17,102 17,963

 426) J K1 mol1, and –(218,543  1746) J K1 mol1 accordingly, that corresponds to reactions: 560E(gr) + 446=2(g) + 45Si(cr) + 48?2(g) ! E560=892Si45?96(lc), 2288E(gr) + 1838=2(g) + 189Si(cr) + 192?2(g) ! E2288=3676Si189?384(lc). In parentheses are indicated the physical states of the reagents (gr stands for graphite, g for gas, cr for crystal and lc for liquidcrystalline). It was interesting to make the hypothetical synthesis of liquidcrystalline carbosilane dendrimers G-n(Und-MPhB)m from appropriate carbosilane dendrimes with terminal allyl groups [G-n(All) m] and appropriate substituted silanes [28,29] and to calculate its entropy at T = 298.15 K and standard pressure (Table 6). The values of standard entropies of synthesis of studied dendrimers per mole of methoxyphenylbenzoate ester of 11tetramethyldisiloxyundecanoic acid have been also computed by us to reveal the dependence of dendrimers thermodynamic properties on the nature of terminal groups and generation number (Table 6). As can be seen, the entropies of synthesis reactions of dendrimers with the same terminal groups but different generations take the same value at this case. Thus, it was concluded that thermodynamic parameters of its synthesis do not depend on number generation and are defined by nature of terminal groups. Besides the fusion temperatures T ofus and also the temperatures of polymorphous transformations (Table 3) for compared dendrimers take the same values. This indicates that thermodynamic properties are more specified by nature of terminal groups rather than generation number. Such conclusion was made us earlier by systematic investigation of carbosilane dendrimers [30,31]. 4. Conclusions

Standard uncertainty of temperature u(T) = 0.01 K. Eombined expanded relative uncertainties for the heat capacity Uc ðC op Þ are 0.02, 0.005 and 0.002; the combined   expanded relative uncertainties Uc;r H ðTÞ  H ð0Þ are 0.022, 0.007 and 0.005;        U c;r S ðTÞ  S ð0Þ are 0.023, 0.008 and 0.006; U c;r G ðTÞ  H ð0Þ are 0.03, 0.01 and 0.009 in the ranges 6 K  T  15 K, 15 K  T  40, and, 40 K  T  370 K, respectively for 0.95 level of confidence (k  2). b Extrapolated. a

From the absolute entropies values of liquid-crystalline carbosilane dendrimers under study at T = 298.15 K (Tables 4 and 5) and absolute entropies of simple substances [C(gr), Si(cr)] [26] and [H2(g), O2(g)] [27] at T = 298.15 K the standard entropies of formation of compounds under consideration were estimated. Obtained values of standard entropies of formation for dendrimers G-2(Und-MPhB)16 and G-4(Und-MPhB)64 are DfSo = (53,306

The heat capacity temperature dependences of liquid-crystalline carbosilane dendrimers of the second and the fourth generations with terminal methoxyphenylbenzoate groups G-2 (Und-MPhB)16 and G-4(Und-MPhB)64 have been measured over the range from 6 to 370 K. The phase transformations were revealed and their thermodynamic characteristics have been determined and analyzed. Particularly, the phase transitions in liquid crystalline state have been detected and their thermodynamic quantities were interpreted with structural parameters. From experimental data the standard thermodynamic functions of studied carbosilane dendrimers, namely, the heat capacity C op ðTÞ, enthalpy H (T)  H (0), entropy S (T)  S (0) and Gibbs energy G (T)  H (0) have been calculated over the range from

Table 6 Standard entropies of synthesis of liquid-crystalline (LC) carbosilane dendrimers at T = 298.15 K. G-n(All)m

H-Si-Und-MPhB

G-2(All)16 h.e.

+

G-4(All)64 h.e.

+

a

G-n(Und-MPhB)m

DrSo

16H-Si-Und-MPhB cr

!

64H-Si-Und-MPhB cr

!

G-2(Und-MPhB)16 LC 3239  28 (202  2) G-4(Und-MPhB)64 LC 12798  115 (200  2)

Reported uncertainties correspond to the combined expanded uncertainties for 0.95 level of confidence (k  2).

(J K1 mol1)a

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T ! 0 to 370 K and entropies of formation of dendrimers in liquidcrystalline state at T = 298.15 K have been calculated. The standard thermodynamic properties of studied dendrimers have been compared and some dependences of dendrimers thermodynamic functions on their composition were obtained. Acknowledgements The work was performed with the financial support of the Ministry of Science and Education (Contract N 4.127 5.2014/K) and the Russian Foundation for Basic Research (project 15-03-02112). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.tca.2015.06.024. References [1] A.M. Muzafarov, E.A. Rebrov, Polym. Sci. Ser. C 42 (2000) 2015. [2] D.A. Tomalia, Macromol. Symp. 101 (1996) 243. [3] J. Barbera, B. Donnio, R. Gimenez, R. Gimenez, D. Guillon, M. Marcos, A. Omenat, J.L. Serrano, Molecular morphology and mesomorphism in dendrimers: a competition between rods and discs, J. Mater. Chem. 11 (2001) 2808–2813. [4] A.I. Kuklin, A.N. Ozerin, A. Kh. Islamov, A.M. Muzafarov, V.I. Gordeliy, E.A. Rebrov, G.M. Ignat’eva, E.A. Tatarinova, R.J. Mukhamedzyanov, L.A. Ozerina, E. Yu. Sharipov, Complementarity of small-angle neutron and X-ray scattering methods for the quantitative structural and dynamical specification on dendritic macromolecules, J. Appl. Cryst. 36 (2003) 679–683. [5] R.M. Richardson, S.A. Ponomarenko, N.I. Boiko, V.P. Shibaev, Liquid crystalline dendrimer of the fifth generation: from lamellar to columnar structure in thermotropic mesophases, Liq. Cryst. 26 (1999) 101–108. [6] N. Boiko, X. Zhu, R. Vinokur, E. Rebrov, A. Muzafarov, V. Shibaev, New carbosilane ferroelectric liquid crystalline dendrimers, Ferroelectrics 243 (2000) 59–66. [7] S.A. Ponomarenko, N.I. Boiko, V.P. Shibaev, R.M. Richardson, I.J. Whitehouse, E. A. Rebrov, A.M. Muzafarov, Carbosilane liquid crystalline dendrimers: from molecular architecture to supramolecular nanostructures, Macromolecules 33 (2000) 5549–5558. [8] S.A. Ponomarenko, N.I. Boiko, V.P. Shibaev, S.N. Magonov, Atomic force microscopy study of structural organization of carbosilane liquid crystalline dendrimer, Langmuir 16 (2000) 5487–5493. [9] V.P. Shibaev, N.I. Boiko, Liquid crystalline silicon-containing dendrimers, Silicon-containing Dendritic Polymers, Springer, 2009237–283. [10] V.P. Shibaev, Liquid crystalline polymers, Polymer Science: A Comprehensive Reference, 1, Elsevier B.V., 2012259–285. [11] U. Ruiz, P. Pagliusi, C. Provenzano, V.P. Shibaev, G. Cipparrone, Supramolecular chiral structures: smart polymer organization guided by 2D polarization light patterns, Adv. Funct. Mater. 22 (2012) 2964–2970.

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