Dendrimers in Solution of Linear Polymers: Crowding Effects

Abstract

We study dendrimers embedded in a solution of linear chains with various degrees of polymerization and concentrations. We distinguish the term “crowding”, addressing the impact of the polymer environment on the dendrimer, from the term “semidilute”, which refers to the state of the polymer environment only. Depending on the length of linear chains, two regimes are observed. Dendrimers in a solution of chains much shorter then their own size display good solvent characteristics at all concentrations. In a dense solution of long chains the dendrimer conformation statistics changes qualitatively. It displays Gaussian scaling with respect to the spacer length instead of the cube root behavior expected for a compact globule. We have found a very good description of the simulation data by using a geometrical ansatz where for crowding given by the matching of the characteristic length scales of the two subsystems; i.e., the ratio of the dendrimer size and the correlation length of the semidilute solution provides the relevant scaling variable. Our study reveals that dendrimer conformations in the strongly crowed state neither are in a compact globular state nor do they correspond to a mean-field θ-state. Instead, a novel scaling variable combining the properties of both species reflects the conformation statistics.

Confined Microenvironments from Thermoresponsive Dendronized Polymers

“…To mimic this striking principle, creation of man‐made confined microenvironment by synthetic chemistry through molecular crowding has drawn tremendous attention, in order to achieve rational conformation or morphologies, functions or properties, which are unfeasible through conventional procedures. [ 7 ] Molecular crowding was revealed for densely substituted crowded arenes, and the bulky dodecyl ether substituents provided a liquid‐like environment to guarantee the formation of 1D stacking columns with a macroscopic dipole moment parallel to the stacking direction. [ 8 ] Confined microenvironment can also be created through cooperative interactions of topological molecules.…”

A method to estimate the size of single-chain nanoparticles under severe crowding conditions

“…3. Eqn (7) provides values of R FG (6.64, 8.65 and 11.27 nm) that are systematically lower (see Fig. 3, green solid squares) than the R FG data from MD simulations (7.3, 9.4 and 12.1 nm).…”

“…For the case of real ring polymers in the melt, it is convenient to express eqn (7) where R e ¼ l(N e /12) 1/2 and l is the monomer length. 25 Eqn ( 8) is strictly valid for N [ N e .…”

“…5 Interestingly, the fractal, crumple globule behaviour of ring polymers under crowding was applied as a tentative model to explain the packing of chromatin bbers into segregated "territories" in the cell nucleus. 6 Moreover, the effect of macromolecular crowding on polymer conformations is of signicant interest in the case of other complex topologies (e.g., dendrimers 7 ) for both academic and practical applications (i.e., dendrimers as processing aids in industrial extrusion processes).…”

“… 6 Moreover, the effect of macromolecular crowding on polymer conformations is of significant interest in the case of other complex topologies ( e.g. , dendrimers 7 ) for both academic and practical applications ( i.e. , dendrimers as processing aids in industrial extrusion processes).…”