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Computer simulations of aggregation of comblike macromolecules with liquid-crystalline side groups in selective solvent
Polovnikov Kirill Under supervision of: Prof. Dr. Igor I. Potemkin


Comblike macromolecules

Oleg E. Perelshtein et al., Mac. R. Comm 28, 2007 Renato V. Iozzo, Annu. Rev. Biochem. 67, 1998


Self-organization of comblikes with stiff side chains

c = 1%

M. Moller et al., Chem. Int. Ed., 51, 2012


Plan


1% solution of symmetric rod-coil macromolecules A

B 1%

AS 0.5
BS 0.5



Organization of a singular comblike macromolecule 1% solution of comblikes



A B 1%

AS 0.5
BS 0.5

Impact of the architecture on resulting structures!


Dissipative particle dynamics
Concervative forces Dissipative forces Random forces





Verlet scheme



aij a ii + 3.27 aii = 25kT

ij

( =3)




Rod-coil semi-dilute solution
A B

«Hockey puck» micelle
Williams, D. R. M.; Fredrickson, G. H Macromolecules, 1992

F=F

elast

+F

rods

-S / k

F elast = Bn 2=( 1-2 AS ) n2 V F rods = BS 2 +( 1- ) ln ( 1- ) V
n ­ average concentration of spacers in the corona; -- volume fraction of rods in the core
Snapshot of the simulation box

a AS = 25, a BS = 40




Rod-coil semi-dilute solution
Means of aggregates analysis


a

BS

Q
16 21 25 26

s
0.28 0.64 0.78 0.82


0.79 0.82 0.87 0.88

Orientational tensor
,

40 50 60 70

3 1 Q = e e - 2 2 1 Q = 3 e ei - i 2Z i



Z -- total number of aggregates in the box

Parameter of nematic ordering:

s = max i ; i = {1, 2, 3 }


Form factor

1 Z E 2= x y + x z + y z E2 = 1-3 2 E1
E 1= x + y + z , k =


i

( r ik )2

Q




Singular comblike macromolecule: star OR bundle

m>d
d m

m



Singular comblike macromolecule: star OR bundle

a AS = 25

a BS = 40

N

rods

=15

dense grafting

a AB = 28
sparse grafting

m = 15 d=5

m = 10 d=5

m=7 d=5

d = 10 m=5

d = 12 m=5

d = 15 m=5


Semi-dilute solution of comblikes c = 1%


necklaces

corn-like bundles

sphere-likes

bundles


1. Regime of soluble backbone
a A S = 25




Semi-dilute solution of comblikes: soluble backbone

a AS = 25

a B S = 40




Semi-dilute solution of comblikes: soluble backbone

spheres

a AS = 25

a B S = 40




Semi-dilute solution of comblikes: soluble backbone




Semi-dilute solution of comblikes: soluble backbone

a AS = 25

a BS =50




Semi-dilute solution of comblikes: soluble backbone

corn-likes

a AS = 25

a BS =50




Semi-dilute solution of comblikes: soluble backbone




Semi-dilute solution of comblikes: soluble backbone

a BS = 40

a BS = 50

a BS =70

sphere-like

corn-like

bundle

= 0.4

=0.6

=0.8




Semi-dilute solution of comblikes: soluble backbone



a BS = 40
a
S


a BS =70

BS


Branching allows for nematic-isotropic transition Improved monodispersity System susceptibility to external stimulus Applicability in sensors





a

BS


1. Regime of extremely soluble backbone
a AS = 15




Semi-dilute solution of comblikes: extremly soluble backbone

sphere-unit necklace

a AS = 15 a BS = 40




Semi-dilute solution of comblikes: extremly soluble backbone

corn-unit necklace

a AS =15 a BS = 50


Isolated micelles

Bound micelles


Results


Comblike solution shows enhanced sensetivity to the solvent dual quality than rod-coil solution; Nematic-isotropic transitions detected; Bound micelles for extremely soluble backbone were acheived for different starting conformations; Further investigation in the area of sparse graftings is promising as may reveal more complex structures (e.g., multilayer vesicles)






Acknowledgements
We would like to thank Grosberg A.U., Ivanov V.A. and Tamm M.V. for prolific discussions Our thank's to R. Gumerov for processing soft RFBR is also gratefully acknowledged






Thank you for attention!