One-step synthesis of sequence-controlled multiblock polymers with up to 11 segments from monomer mixture

Switchable polymerization holds considerable potential for the synthesis of highly sequence-controlled multiblock. To date, this method has been limited to three-component systems, which enables the straightforward synthesis of multiblock polymers with less than five blocks. Herein, we report a self-switchable polymerization enabled by simple alkali metal carboxylate catalysts that directly polymerize six-component mixtures into multiblock polymers consisting of up to 11 blocks. Without an external trigger, the catalyst polymerization spontaneously connects five catalytic cycles in an orderly manner, involving four anhydride/epoxide ring-opening copolymerizations and one L-lactide ring-opening polymerization, creating a one-step synthetic pathway. Following this autotandem catalysis, reasonable combinations of different catalytic cycles allow the direct preparation of diverse, sequence-controlled, multiblock copolymers even containing various hyperbranched architectures. This method shows considerable promise in the synthesis of sequentially and architecturally complex polymers, with high monomer sequence control that provides the potential for designing materials.

Symmetric RAFT-agent for synthesizing multiblock copolymers with different activated monomers

With a bifunctional symmetric RAFT agent well-defined polymer structures can be achieved. This paper shows the possibility to synthesize block copolymer systems consisting out of different activated monomers. With the novel bifunctional symmetric RAFT agent water-born polymer systems with a block structure (B-b-A-b-B) can be polymerized. The symmetric RAFT agent is designed to polymerize both more activated monomers (A) and less activated monomers (B). Due to the ability of a controlled radical polymerization of different activated monomers the dispersity of the resulting polymers is broader compared to common RAFT polymerizations. In regard to industrial applications like emulsifiers, stabilizers or viscosity modifiers the broader molecular weight distribution has no impact. Overall, this paper shows the possibility towards new functional polymers with unique properties.

Membrane Separation of Gaseous Hydrocarbons by Semicrystalline Multiblock Copolymers: Role of Cohesive Energy Density and Crystallites of the Polyether Block

The energy-efficient separation of hydrocarbons is critically important for petrochemical industries. As polymeric membranes are ideal candidates for such separation, it is essential to explore the fundamental relationships between the hydrocarbon permeation mechanism and the physical properties of the polymers. In this study, the permeation mechanisms of methane, ethane, ethene, propane, propene and n-butane through three commercial multiblock copolymers PEBAX 2533, PolyActive1500PEGT77PBT23 and PolyActive4000PEGT77PBT23 are thoroughly investigated at 33 °C. This study aims to investigate the influence of cohesive energy density and crystallites of the polyether block of multiblock copolymers on hydrocarbon separation. The hydrocarbon separation behavior of the polymers is explained based on the solution–diffusion model, which is commonly accepted for gas permeation through nonporous polymeric membrane materials.

Precise Synthesis and Thermoresponsive Property of Poly(ethyl glycidyl ether) and Its Block and Statistic Copolymers with Poly(glycidol)

In this paper, we describe a comprehensive study of the thermoresponsive properties of statistic copolymers and multiblock copolymers synthesized by poly(glycidol)s (PG) and poly(ethyl glycidyl ether) (PEGE) with different copolymerization methods. These copolymers were first synthesized by ring-opening polymerization (ROP), which was initiated by tert-butylbenzyl alcohol (tBBA) and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ5,4Λ5-catenadi(phosphazene) (t-Bu-P4) as the catalyst, and then the inherent protective groups were removed to obtain the copolymers without any specific chain end groups. The thermoresponsive property of the statistic copolymer PGx-stat-PEGEy was compared with the diblock copolymer PGx-b-PEGEy, and the triblock copolymers were compared with the pentablock copolymers. Among them, PG-stat-PEGE, PG-b-PEGE-b-PG-b-PEGE-b-PG, and PEGE-b-PG-b-PEGE-b-PG-b-PEGE, and even the specific ratio of PEGE-b-PG-b-PEGE, exhibited LCST-type phase transitions in water, which were characterized by cloud point (Tcp). Although the ratio of x to y affected the value of the Tcp of PGx-stat-PEGEy, we found that the disorder of the copolymer has a decisive effect on the phase-transition behavior. The phase-transition behaviors of PG-b-PEGE, part of PEGE-b-PG-b-PEGE, and PG-b-PEGE-b-PG copolymers in water present a two-stage phase transition, that is, firstly LCST-type and then the upper critical solution temperature (UCST)-like phase transition. In addition, we have extended the research on the thermoresponsive properties of EGE homopolymers without specific α-chain ends.

Synthesis of thermally protective PET–PEG multiblock copolymers as food packaging materials

One of the storage conditions affecting quality of food stuffs due to short shelf life is temperature. Thermal insulation can be achieved by adding phase change materials (PCMs) to packaging materials. PCMs store and release latent heat of phase change during melting and crystallization operations, respectively. Thus, they can provide thermal protection for packaged foods. The aim of this study is to prepare new food packaging materials poly (ethylene terephthalate)–poly (ethylene glycol) (PET–PEG) multiblock copolymers as solid–solid phase change materials (SSPCM) as potential food packaging materials with thermal energy storage (TES) property. Polyesterification was carried out with PEG at different average molecular weights (1000, 4000 and 10,000 g/mol), ethylene glycol (EG) and terephthaloyl chloride (TPC). Synthesized PET–PEG multiblock copolymers were characterized using Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) methods. The crystal structures of PET–PEG multiblock copolymers were characterized by polarized optical microscopy (POM) and their surface properties were determined by performing contact angle tests. TES capacity of the PET–PEG multiblock copolymers was found in range of 26.1–150.5 J/g. Consequently, this study demonstrates the potential of PET–PEG multiblock copolymers suitable for effective thermal preservation in packaging material applications to maintain the quality of packaged food stuffs.

Organosilica-Modified Multiblock Copolymers for Membrane Gas Separation

Organosubstituted silica derivatives were synthesized and investigated as modifiers of block copolymers based on macroinitiator and 2,4-toluene diisocyanate. A peculiarity of the modified block copolymers is the existence in their structure of coplanar rigid polyisocyanate blocks of acetal nature (O-polyisocyanates). Organosubstituted silica derivatives have a non-additive effect on high-temperature relaxation and α-transitions of modified polymers and exhibit the ability to influence the supramolecular structure of block copolymers. The use of the developed modifiers leads to a change in the gas transport properties of block copolymers. The increase of the permeability coefficients is due to the increase of the diffusion coefficients. At the same time, the gas solubility coefficients do not change. An increase in the ideal selectivity for a number of gas pairs is observed. An increase in the selectivity for the CO2/N2 gas pair (from 25 to 39) by 1.5 times demonstrates the promising use of this material for flue gases separation.