Zhenghe Zhang

Synthesis of fluorine-containing block copolymers via ATRP 2. Synthesis and characterization of semifluorinated di- and triblock copolymers ☆

Abstract A series of semifluorinated fluorocarbon/hydrocarbon di- and triblock copolymers were prepared by atom transfer radical polymerization (ATRP). The mono- and difunctional macroinitiators, which were obtained from bulk ATRP of styrene, butyl acrylate and methyl acrylate, initiated solution ATRP of 2-[(perfluorononenyl)oxy]ethyl methacrylate and ethylene glycol mono-methacrylate mono-perfluorooctanoate, respectively. The formation of the block copolymer was confirmed with size exclusion chromatography and 1 H NMR spectrum.

Recent advances in organic–inorganic well-defined hybrid polymers using controlled living radical polymerization techniques

Hybrid organic–inorganic materials comprised of well-defined polymers have been widely recognized for a variety of applications due to their extraordinary properties based on the combination of the different building compositions. During the past decades, many kinds of well-defined hybrid polymers with a variety of architectures have been constructed by polymerization in the presence of inorganic compositions, or by the coupling reaction of functional polymers with inorganic nanoparticles. Thus, techniques could be utilized for the preparation of well-defined organic–inorganic hybrid polymers, including controlled living radical polymerizations (CLRP), such as atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain transfer (RAFT) polymerization. Organic–inorganic hybrid polymers based on polyhedral oligomeric silsesquioxane (POSS), poly(dimethylsiloxane) (PDMS), silica nanoparticles, graphene, carbon nanotubes (CNTs) and fullerene will be discussed in this paper.

One-pot synthesis of POSS-containing alternating copolymers by RAFT polymerization and their microphase-separated nanostructures

The poly(styrene-alt-maleimide isobutyl POSS) (PSMIPOSS) alternating copolymer is one-pot synthesized via reversible addition-fragmentation transfer (RAFT) polymerization. The results show that a POSS-containing alternating copolymer with a high degree of polymerization (DP) and a low polydispersity index (PDI) is successfully constructed by alternating copolymerization of maleimide isobutyl POSS with styrene, and the molecular weight of the PSMIPOSS alternating copolymer can be well controlled by the amount of RAFT agent. Poly(styrene-alt-maleimide isobutyl POSS)-block-polystyrene (PSMIPOSS-b-PS) block copolymers are also one-pot prepared by RAFT polymerization, and their self-assembly behavior in the bulk is investigated by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), which exhibit a series of short-range order phase transitions from the POSS sphere, POSS cylinder to lamella structures with the weight fraction of MIPOSS ranging from 13% to 64%. The thermal properties of POSS-containing copolymers are evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The results display that MIPOSS units can enhance the thermal properties of copolymers effectively.

One-pot synthesis of well-defined amphiphilic alternating copolymer brushes based on POSS and their self-assembly in aqueous solution

Poly(maleimide isobutyl polyhedral oligomeric silsesquioxane-alt-vinylbenzyl polyethylene glycol) (P(MIPOSS-alt-VBPEG)) amphiphilic copolymer brushes with a sequence of alternating MIPOSS and polyethylene glycol (PEG) side chains were synthesized via ordinary radical polymerization and reversible addition–fragmentation transfer (RAFT) polymerization. A series of alternating copolymer brushes prepared by RAFT polymerization had a low polydispersity index (PDI) of less than 1.25. The thermal properties of these copolymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results displayed that the MIPOSS units could effectively enhance the thermal properties of the hybrid copolymers. The self-assembly behavior of the P(MIPOSS-alt-VBPEG) amphiphilic copolymer brushes in aqueous media was also studied by fluorescence spectrophotometry (FS), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results showed that these alternating copolymer brushes could form spherical aggregates in water.

Synthesis of POSS-functionalized liquid crystalline block copolymers via RAFT polymerization for stabilizing blue phase helical soft superstructures

A series of POSS-functionalized liquid crystalline block copolymers (LC BCPs), PHEMAPOSS-b-P6CBMA, containing a crystalline polyhedral oligomeric silsesquioxane (POSS) block and a mesogenic cyanobiphenyl block, were prepared via reversible addition–fragmentation transfer (RAFT) polymerization for the first time and utilized to stabilize blue phase (BP) liquid crystals through facile doping. Using the advantages of both the POSS and polymer, a new strategy, which is distinct from the commonly adopted strategy for polymer stabilization of the BP, has been established. This new BP system with a wide BP range covering the typical room temperature range (i.e. 25–30 °C) leaps over intricate processing barriers, which are inevitable in conventional photo-induced polymer stabilization. In particular, improved electro-optical (E-O) properties of the BP, including lower driving voltage, lower hysteresis and a higher Kerr constant (K) compared with the common BP stabilized via photopolymerization, were obtained by optimizing the concentration of the doped LC BCP. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to evaluate the thermal properties of the LC BCPs, and the results indicated that the introduction of POSS enhanced the thermostabilities of the copolymers effectively. Such an ingenious strategy provides a brilliant and easy way to form large size BP displays and other devices that are incompatible with UV light exposure during the working process.