Chuanjie Cheng

Synthesis and use of a surface-active initiator in emulsion polymerization under AGET and ARGET ATRP conditions

A novel surface-active ATRP initiator disodium 4-(10-(2-bromo-2-methylpropanoyloxy)decyloxy)-4-oxo-2-sulfonatobutanoate (1a) has been designed and synthesized efficiently in three steps. The controlled radical emulsion polymerizations of methyl methacrylate (MMA) were realized in one step without any added surfactant under AGET and ARGET ATRP conditions, in which the initiator 1 functioned as both an ATRP initiator and a latex stabilizer.

Self-healing polymers based on a photo-active reversible addition-fragmentation chain transfer (RAFT) agent

A symmetric photo-active trithiocarbonate was designed and synthesized, which can act not only as a functional reversible addition-fragmentation chain transfer (RAFT) agent, but also as a crosslinker in crosslinking poly(methyl methacrylate-co-hydroxy ethyl acrylate) (poly(MMA-co-HEA)) due to interactions of benzophenone moieties of trithiocarbonate and hydroxyl groups of poly(MMA-co-HEA) under UV irradiation. In addition, the crosslinked poly(MMA-co-HEA) demonstrates photo-promoted self-healing properties by reshuffling C-S bonds of trithiocarbonate.

Preparation of Fully Bio-Based UV-Cured Non-Isocyanate Polyurethanes From Ricinoleic Acid

Fully bio-based non-isocyanate polyurethane (NIPU) was facilely prepared by self-condensation of primary amide of ricinoleic acid under oxidation conditions. The resulting linear urethane oligomer (Mn = 1300 Da) as a viscous liquid was further cured under UV light irradiation to afford a polymer film with hardness of lower than 2B. Infrared spectra as well as changes of polymer appearance proved crosslinking of the linear NIPU. Hardness of UV-cured film was promoted to 4H when a certain amount of cardanol was added to the linear urethane oligomer, accompanied by manifest improvement of resistance to chemical media such as aqueous HCl, EtOH, toluene and THF.

Facile synthesis of block copolymers from a cinnamate derivative by combination of AGET ATRP and click chemistry

An azido- and bromo-containing compound derived from naturally occurring ethyl cinnamate was used successfully to prepare block copolymers by a combination of ‘activator generated by electron transfer atom transfer radical polymerization’ (AGET ATRP) and Huisgen “click” reactions in emulsion. First, azido-end poly(methyl methacrylate) and alkyne-end polystyrene were prepared under AGET ATRP conditions, then, poly(methyl methacrylate) block polystyrene (PMMA-b-PS) diblock copolymer was formed by Huisgen 1,3-dipolar cycloaddition. Finally, polystyrene block poly(methyl methacrylate) block polystyrene (PS-b-PMMA-b-PS) triblock copolymer was synthesized via simultaneous AGET ATRP and click reactions, catalyzed by the same copper-based catalyst. The polymers were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC), which confirmed the successful synthesis of the corresponding polymers.

Synthesis of a photoactive gemini surfactant and its use in AGET ATRP miniemulsion polymerisation and UV curing

A novel photoactive gemini surfactant was easily synthesised in high yields. The multi-functional molecule can be used as a gemini surfactant, a benzophenone type photoinitiator, and as an ATRP initiator. Poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate)-block-poly(allyl methacrylate) (PMMA-b-PAMA) were prepared using the photoactive gemini surfactant as an ATRP initiator under soap-free miniemulsion polymerisation conditions. Kinetic results of the miniemulsion polymerisation of methyl methacrylate (MMA) indicate that the reaction has controlled/living characteristics. UV curing was performed by irradiation of the linear PMMA-b-PAMA polymer, in which PMMA-b-PAMA containing a benzophenone moiety functioned as a macromolecular photoinitiator.

Syntheses of cardanol-based cationic surfactants and their use in emulsion polymerisation

Six quaternary ammonium salts were designed and synthesised with moderate to high yields in three steps, based on cardanol, a low-cost and abundant renewable resource. The new ammonium salts can act as reactive surfactants due to their having both a hydrophilic ammonium group and a hydrophobic unsaturated alkyl chain. The gemini surfactants with a linker of a linear saturated aliphatic hydrocarbon chain exhibited a relatively low CMC value (≤ 0.2 mmol L−1) and surface tension (≤ 27 mN m−1), signifying that this kind of amphiphile exhibited good surface active properties. The photo-active gemini surfactant with critical micelle concentration (CMC) of 0.05 mmol L−1 was used successfully as the sole emulsifier in the emulsion polymerisation of methyl methacrylate (MMA). In addition, a benzyl bromide-containing surfactant can act as both an atom transfer radical polymerisation (ATRP) initiator and an emulsifier in an activator generated by the electron transfer atom transfer radical polymerisation (AGET ATRP) of MMA in emulsion. The value of the number-average molecular mass of the resulting cardanol-end poly(methyl methacrylate) (PMMA) is Mn,GPC = 45.1 kDa, with polydispersity of 1.39.

Synthesis of cardanol-based photo-active SET-LRP initiator and its application to preparation of UV-cured resin

A benzophenone-containing SET-LRP initiator based on renewable and abundant cardanol was synthesised in 71 % yield using the selective etherification reaction. Next, methyl methacrylate (MMA) as a monomer was polymerised under SET-LRP conditions using the newly prepared initiator to prepare cardanol-end poly(methyl methacrylate) (PMMA). The kinetic results of the polymerisation indicated that the reaction was controllable when the monomer conversion was lower than approximately 50 %, and the molecular masses of PMMA measured by GPC were higher than the theoretical values while the monomer conversion was more than 50 %. In addition, most of the carbon-carbon double bonds of the side hydrocarbon chain of the end-cardanol group in the PMMA were kept intact from 1H NMR spectrum characterisation. Accordingly, when the cardanol-end PMMA together with a tertiary amine-containing cardanol derivative was irradiated by UV light, the corresponding UV-cured resin was obtained. The chemical resistance and hardness of the UV-cured film were enhanced with the increasing irradiation time.

Single Electron Transfer Living Radical Polymerization via a New Initiator

Research and development of novel initiating system such as single electron transfer living radical polymerization (SET-LRP) is of high importance in polymer chemistry. A new SET-LRP initiator was synthesized and applied to prepare end-functionalized poly(methyl methacrylate) (PMMA) in this study. ?-Trichloromethyl benzyl alcohol was firstly synthesized, followed by preparation of PMMA under SET-LRP conditions. Conversion of MMA was 81.9%, and the molecular weight of PMMA was about 2.5 kDa at 60 ?C for 1 h. Consistency of the number-average molecular weight of PMMA from NMR, GPC and theoretical calculation indicated that the polymerization featured controllable property. Broad molecular weight distribution (MWD) may be ascribed to branched polymers formed by initiation and chain transfer.

Synthesis and spectral properties of triazine-based dendritic dithienylethenes

Two novel triazine-based dendrimers comprising a dithienylethene core and eight and 16 ethyl groups around the periphery were synthesised in high yields in a convergent way, without using tedious protection and chromatographic separation steps. Their optical properties such as photochromism, fluorescence emission and film-forming behaviour were investigated. The new symmetrical dendritic dithienylethenes showed typical photochromic behaviour in solution and good film-forming performance in a poly(methyl methacrylate) (PMMA) matrix. Moreover, the dendrimers have demonstrated remarkable fluorescence enhancement and good solubility in common organic solvents, compared with the corresponding small molecule diarylethene. Thus, the new dendrimers as optoelectronic materials, have potential applications in optical storage, photo-switches, and so on.