Synthesis, Molecular Characterization, and Phase Behavior of Miktoarm Star Copolymers of the AB_n and A_nB (n = 2 or 3) Sequences, Where A Is Polystyrene and B Is Poly(dimethylsiloxane)

Abstract

Novel miktoarm star copolymers of polystyrene[poly(dimethylsiloxane) n ] or PS(PDMS) n (n = 2 or 3) type as well as of the inversed sequence, namely, (polystyrene) n [poly(dimethylsiloxane)] or (PS) n PDMS (n = 2 or 3), were synthesized by combining living anionic polymerization with chlorosilane chemistry. The miktoarm star copolymers were extensively characterized through size exclusion chromatography, vapor pressure/membrane osmometry, proton nuclear magnetic resonance, and differential scanning calorimetry, in order to verify the successful synthesis. All samples with varying volume fractions and narrow dispersity indices (D̵ < 1.1) were morphologically characterized by transmission electron microscopy and small-angle X-ray scattering, in order to study their self-assembly behavior as well as to examine the effect of the complex architecture on the final adopted morphologies. For specific PS(PDMS) n (n = 2 or 3), morphologies different from those expected from theoretical predictions (self-consistent field theory or Gaussian statistics) were obtained, while for the inversed sequences, namely, (PS) n PDMS (n = 2 or 3), no discrepancies were evident. This fact further confirmed the impact of the number of arms as well as the flexibility of the segments (PS being stiffer than PDMS) on the structure/property relationship.

Conventional Non‐Fluorescent Polymers: Unconventional Security Inks for Data Storage and Multidimensional Photonic Cryptography

“…This is very interesting as it offers a feasible way to visually discriminate polymers with different topologies for the first time. Though conventional methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and MALDI‐MS, can visualize the topology of polymers or determine the topology by the mass of terminal groups, [ 19 ] they generally suffer from a number of drawbacks, such as poor handleability, time‐consuming, tedious operations, and expensive. This polymer topology‐induced emission change offers a unique way for data encryption and anticounterfeiting.…”

Thermal and Bulk Properties of Triblock Terpolymers and Modified Derivatives towards Novel Polymer Brushes

“…For the semicrystalline PDMS block, additional transitions were observed at approximately −40 °C and −70 °C, indicating the melting and crystallization of the siloxane crystals, respectively, due to the increased molecular weight of the specific segment (sample 1) compared to the remaining terpolymers. The lower than expected value for the T g of the PS block is extensively analyzed in the literature [ 41 , 42 ].…”

“…The specifics regarding TEM and SAXS measurements are provided elsewhere [ 42 ]. The triblock terpolymers were cast from a dilute solution in toluene (5 wt%), and the solvent evaporation was completed in approximately 7 days.…”

Quo Vadis Carbanionic Polymerization?

“…Avgeropoulos’ group reported the synthesis and self-assembly of various types of well-defined miktoarm star polymers and dendrimers consisting of PS and immiscible polydiene blocks or PDMS via anionic polymerization high-vacuum techniques and appropriate chlorosilane chemistry. − On the other hand, other groups developed new multifunctional initiators for the anionic polymerization of styrene and dienes generating star homo/copolymers. , These DPE-based new initiators were soluble in hydrocarbon solvents and did not require polar additives during the polymerization …”