Copolymers of chosen alkyl methacrylates with N-phenylmaleimide and N-(4-halogenphenyl)maleimides: A UV-aging study

Homopolymers and copolymers of ethyl and butyl methacrylates with N-phenylmaleimide, N-(4-chlorophenyl)maleimide, and N-(4-bromophenyl)maleimide were synthesized by free-radical bulk polymerization with benzoyl peroxide as the initiator. The content of imide in the copolymers was about 5–10 or 7.5 wt %. The homopolymers and copolymers were irradiated with ultraviolet (UV) light in a climatic test chamber for various periods to study their aging behavior. After 100, 250, and 500 h, the structure, thermal stability, chemical resistance, and some physicomechanical properties were examined. The influence of UV radiation time on structure and the investigated properties of the homopolymers and copolymers were studied. The experimental results indicate that all investigated copolymers were resistant to UV radiation after 500 h. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3244–3250, 2001     

Single-ion conduction in UV-crosslinked films of poly(urethane-co-(alkali-metal methacrylates))

A series of crosslinked copolymers of poly(ethylene glycol-co-2,4-tolyl diisocyanate-co-(alkali-metal methacrylates)) were prepared by copolymerization of polyurethane oligomer with alkali-metal methacrylate. Cast films of these copolymers obtained by UV-crosslinked polymerization are completely amorphous and have a relatively low T_g. The films provide good mechanical properties and high ionic conductivity without additional solvent or inorganic salts. DC ionic conductivity of the films at room temperature is stable over time indicating that the copolymer is a cationic single-ion conductor. AC conductivity of these films depends mainly on the ionic radius, segmental motion of the polymer chains and local environment of the ions in the polymer matrix.     

TAC对DAIP树脂体系的改性研究

研究了三聚氰酸三烯丙基酯 (TAC)对间苯二甲酸二烯丙基酯 (DAIP)树脂体系的耐热性能、力学性能、介电性能以及耐水性能的影响。结果表明 ,加入一定量的TAC可以明显提高DAIP树脂的耐热性。     

Kinetics analysis and physical properties of photocured silicate-based thiol-ene nanocomposites: The effects of vinyl POSS ene on the polymerization kinetics and physical properties of thiol-triallyl ether networks

The kinetics and thermal/physical properties of the trithiol-TAE (triallyl ether) system were measured with respect to increasing polyoligomeric silsesquioxane (POSS) concentrations in order to understand how the presence of POSS nanoparticles affects network formation at low loadings. Vinyl POSS monomer (vPOSS-Bu₄) with both vinyl and carboxylate pendant groups was synthesized via a thermally initiated, free-radical reaction to improve the compatibility of the inorganic particles with the trithiol and triallyl ether comomoners. Chemically modified vPOSS-Bu₄ particles were incorporated into the trithiol-TAE polymer networks by a thiol-ene free-radical photopolymerization at molar concentrations of 0, 1, and 5 ene mol%. The polymerization rates were analyzed using real-time FTIR and photo-DSC. The polymerization rates showed no significant changes with increasing vPOSS-Bu₄ concentration. Thermal analyses of the films by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated that thermal stability improves without affecting T _g as the POSS concentration increased. Additionally, scratch resistance increased and flame spread decreased markedly with increasing POSS concentration for concentrations up to 5 mol% vPOSS-Bu₄.     

Intumescent fire-retardant coatings for plastics based on poly(vinylphosphonic acid): Improving water resistance with comonomers

Coatings based on the in situ photopolymerization of vinyl phosphonic acid (VPA) with triallyl cyanurate as a crosslinking agent are shown to be effective not only for fire-protecting glass fiber-reinforced epoxy resin (GRE) composites but also poly(methyl methacrylate) (PMMA), a typical meltable and flammable thermoplastic. Dry adhesion of polyVPA coatings to PMMA surfaces is excellent but, as with coatings on GRE, adhesion following water-soak tests is poor. Copolymerizing VPA with more hydrophobic monomers improves wet adhesion, albeit with some impairment of fire performance, with copolymers of VPA and acrylonitrile giving the best results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47601.     

Effect of crosslinkers on the preparation and properties of ETFE‐based radiation‐grafted polymer electrolyte membranes

This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2‐bis(p,p‐vinylphenyl)ethane (BVPE), and triallyl cyanurate (TAC) crosslinked poly(ethylene‐co‐tetrafluoroethylene) (ETFE)‐based radiation‐grafted membranes, which were prepared by radiation grafting of p‐methylstyrene onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity, and thermal/chemical stability of the resulting polymer electrolyte membranes were investigated in detail. Introducing crosslink structure into the radiation‐grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation‐grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation‐grafted membranes show significantly higher chemical stability characterized in the 3% H₂O₂ at 50°C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation‐grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4565–4574, 2006     

氰尿酸三烯丙酯的合成研究进展

介绍了氰尿酸三烯丙酯(TAC)的理化性质及其应用领域。综述了TAC国内外的合成研究进展情况,指出了今后的改进方向。     

Synthesis of poly(lactic acid-b-p-dioxanone) block copolymers from ring opening polymerization of p-dioxanone by poly(L-lactic acid) macroinitiators

Poly(lactic acid-b-p-dioxanone) block copolymers (P(LA-b-PDO)) were synthesized by ring-opening polymerization of p-dioxanone using poly(lactic acid) (PLA) with different molecular weights as macroinitiators in N₂ atmosphere. The copolymers were characterized by ¹H-NMR spectra. The thermal and crystalline behaviors and thermal stability of these copolymers were investigated by DSC, TGA and WAXD. The results indicated that the contents of each segment and the intrinsic viscosities affected the properties of copolymers obviously.     

Gamma‐ray irradiation effect of polyethylene on dimaleimides as a class of new multifunctional monomers

Multifunctional monomers, m‐xylylenedimaleimide, p‐phenylenedimaleimide, m‐phenylenedimaleimide, and p‐phenylenedinadimide, all of which have maleimide groups, were synthesized to increase thermal and radiation stabilities. The synthesized multifunctional monomers showed good compatibility with low‐density polyethylene (LDPE). Mixtures of LDPE and these multifunctional monomers were irradiated with γ‐rays from a Co‐60 source at room temperature in a nitrogen atmosphere. The absorbed dose ranged from 0 to 160 KGy. Among these multifunctional monomers, m‐xylylenedimaleimide was the best in gel fraction enhancement. Crosslinked LDPE with m‐xylylenedimaleimide displayed a higher modulus than that of crosslinked LDPE with triallyl cyanurate. For the elongation property, LDPE with m‐xylylenedimaleimide as a multifunctional monomer showed better results than that with commercial multifunctional monomers such as triallyl cyanurate (TAC) and trimethylol propane triacrylate (TMPTA). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2339–2345, 2003     

Recent studies on interpenetrating polymer networks

Recent investigations on interpenetrating polymer networks (IPNs) have included two component IPNs from polyurethanes and poly(methacrylates) and two component IPNs from polyurethanes and epoxies. All the IPNs were prepared by the simultaneous polymerization technique (SIN-IPNs). Two types of IPNs, polyurethane-poly(methyl methacrylate) (PU/PMMA) and polyurethane-poly(methyl methacrylate-methacrylic acid) (PU/PMMA-MAA) were prepared. Improved phase miscibility and decreasing extent of phase separation was observed in both types of IPNs with increasing the NCO/OH ratio, decreasing molecular weight of the polyol in the PU and introduction of charge groups. A comparison was made between full-IPNs, pseudo-IPNs, graft copolymers and related homopolymers from polyurethanes and epoxies. Increased compatibility in full-IPNs and graft copolymers was observed by means of DSC, SEM and was also further substantiated by a shift toward single T_gs as determined by dynamic mechanical spectroscopy. The introduction of opposite charge groups in two-component IPNs from polyurethanes and epoxies led to improved compatibility (no phase separation) and enhanced mechanical properties.     

Positively charged nanomicelles in water of amphiphilic copolymer chitosan-g-polylactide as drug carrier of photoporphyrin IX for photodynamic therapy

Preparation of amphiphilic graft copolymers of chitosan-g-methacrylate-terminated poly(lactic acid) (CS-g-MPLA_n) with various chain length of lactic acid monomers in the copolymers (n = 20, 40, and 70) has been successfully carried out by “grafting on” free radical polymerization. Beside to offer a tunable and easy preparation of chitosan (CS)-based amphiphilic copolymers, the specific purpose is to study the effects of poly(lactic acid) chain length on the micelle properties of the copolymers in water. First, oligomer CS was synthesized by partial oxidation. Second, the methacrylate-terminated poly(lactic acid) with different chain length were synthesized by ring opening polymerization of lactide monomer using 2-hydroxyethyl methacrylate and Sn(Oct)₂ as initiator and catalyst, respectively. Finally, the grafting process was carried out by free radical copolymerization using cerium(IV) sulfate as initiator at 70°C for 24 h. The CS-g-MPLA_n amphiphilic copolymers were characterized by Fourier transform infrared and proton nuclear magnetic resonance. The hydrophobic drug nanomicelles in water with a narrow-size distribution, positively charged and high stability have been confirmed. The micelle size is significantly bigger on longer chain of poly(lactic acid); however, the stability, loading capacity, and encapsulation efficiency are independent on the chain length. The high-loading capacity and encapsulation efficiency for hydrophobic drug protoporphyrin IX as the model are ensuring the hydrophobic drugs efficacy in photodynamic therapy applications.     

Accelerant‐promoted free radical polymerization of methacrylates by stabilized nitroxide unimolecular initiators: synthesis and characterization

BACKGROUND: This investigation evaluates the effectiveness of initiator adducts for living and controlled polymerization of methacrylates, crosslinking of dimethacrylates and thermal stabilities of the resulting polymers. Adducts of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy with benzoyl peroxide and with azobisisobutyronitrile were prepared and evaluated as stabilized unimolecular initiators for the free radical polymerization of methacrylate monomers using sulfuric acid as catalyst. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Successful polymerization was achieved at 70 and 130 °C with reaction times ranging from 45 min to 120 h. The dispersity (D) of poly(methyl methacrylate) (PMMA) was 1.09–1.28. The livingness and extent of control over polymerization were confirmed with plots of M_n evolution as a function of monomer conversion and of the first‐order kinetics. The glass transition temperature (T_g) for PMMA was 123–128 °C. The degradation temperature (T_d) for PMMA was 350–410 °C. T_d for poly(TEGMA) was 250–310 °C and for poly(EBPADMA) was 320–390 °C. CONCLUSION: The initiators are suitable for free radical living and controlled polymerization of methacrylates and dimethacrylates under mild thermal and acid‐catalyzed conditions, yielding medium to high molecular weight polymers with low dispersity, high crosslinking and good thermal stability. Copyright © 2008 Society of Chemical Industry     

New syntheses of graft copolymers using the DPE-technique: ATRP graft copolymerization

Summary A new one-step synthesis of a set of macroinitiators for atom transfer radical polymerization (ATRP) via controlled radical polymerization is presented. The macroinitiators consist of methacrylate and p-chloromethylstyrene (CMS) and were synthesized by controlled radical polymerization in the presence of l,l-diphenylethylene (DPE) using azobisisobutyronitrile (AIBN) as initiator. The resulting macroinitiators were used for the ATRP of different methacrylates yielding graft copolymers which were characterized by SEC and NMR. Received: 25 July 2002/Revised version: 28 October 2002/ Accepted: 28 October 2002 Correspondence to Oskar Nuyken     

Examining the preparation and characterization of coatings based on linear aromatic terpoly(methoxy‐cyanurate‐thiocyanurate)s

Two series of terpoly(methoxy‐cyanurate‐thiocyanurate)s based on thiodiphenol and dithiodiphenyl sulfide and on dihydroxydiphenyl ether and dithiodiphenyl ether, were prepared in good yield and purity and fully characterized. Most of the resulting polymers, formed at room temperature using phase transfer catalysis, can be cast into films with good resilience and thermal stability (some examples suffer practically no mass loss when held isothermally at 190 °C and only display appreciable losses when held continuously at 225 °C). Char yields of 53%?61% are achieved in nitrogen depending on backbone structure. Some problems were encountered with solubility, particularly with copolymers, which limited molecular weight analysis, but values of M_n = 8000–13 000 g mol^?1 were obtained for the polymers based on thiodiphenol and dithiodiphenyl sulfide, and M_n = 5000–13 000 g mol^?1 for the polymers based on dihydroxydiphenyl ether and dithiodiphenyl ether. DSC reveals polymerization exotherms with maxima at 184–207 °C (ΔH_p = 43–59 kJ mol^?1), which are believed to be due to isomerization of the cyanurate to the isocyanurate (activation energies span 159–195 kJ mol^?1). Molecular simulation shows that diphenylether and diphenylsulfide display very similar conformational energy surfaces and would therefore be expected to adopt similar conformations, but the diphenylsulfide offers less resistance to deformations that increase the proximity of the two phenyl rings and results in more resilient films. © 2013 Society of Chemical Industry     

ABA triblock copolymers from poly(p‐dioxanone) and poly(ethylene glycol)

Poly(p‐dioxanone)–poly(ethylene glycol)–poly(p‐dioxanone) ABA triblock copolymers (PEDO) were synthesized by ring‐opening polymerization from p‐dioxanone using poly(ethylene glycol) (PEG) with different molecular weights as macroinitiators in N₂ atmosphere. The copolymer was characterized by ¹H NMR spectroscope. The thermal behavior, crystallization, and thermal stability of these copolymers were investigated by differential scanning calorimetry and thermogravimetric measurements. The water absorption of these copolymers was also measured. The results indicated that the content and length of PEG chain have a greater effect on the properties of copolymers. This kind of biodegradable copolymer will find a potential application in biomedical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1092–1097, 2006     

A study of the thermal and mechanical properties of electron beam irradiated HDPE/EPDM blends in the presence of triallyl cyanurate

The enhancing effects of cross-linking by the addition of 1, 3, and 5 wt% of triallyl cyanurate (TAC) to blends containing 80 wt% of high-density polyethylene (HDPE) and 20 wt% of ethylene–propylene diene monomer (EPDM) during electron beam irradiation were investigated. More specifically, the thermal and mechanical properties were studied as a function of the electron beam irradiation dose and an amount of the cross-linking agent, such as triallyl cyanurate (TAC). The results showed that the values of the gel content, thermal stability, tensile properties, impact strength, and rheology increased with increasing irradiation dose up to 150 kGy. For higher doses, the values decreased. Addition of the cross-linking agent to the HDPE/EPDM blends showed an enhanced cross-linking effect of various properties during electron beam irradiation. The addition of 3 wt% of TAC led to the highest thermal and mechanical properties. An irradiation dose of 150 kGy with the addition of 3 wt% TAC was the optimal condition to obtain blends with the best properties.     

Poly(2,2-dimethyltrimethylene carbonate)-block-poly(dimethylsiloxane)-block-poly(2,2-dimethyltrimethylene carbonate). Synthesis and thermal properties

Lithium salts of hydroxytelechelic poly(dimethylsiloxane) [poly-(DMS)] were used as initiators for the anionic ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC). Triblock copolymers were obtained in high yields. Complexation of the active site in DTC polymerization by the poly(DMS) chain leads to a decrease in polymerization rate. The thermal properties of the copolymers of different compositions were determined. Catalysed thermal degradation of the block copolymers leads to cyclic oligomers D_n and DTC upon ring-closing depolymerization.     

Structurally controlled polymerizations of methacrylates and acrylates

Progress in the structure control of polymethacrylates and polyacrylates through stereospecific living polymerization are described. Three types of stereospecific living polymerizations have been developed for methacrylate polymerization: isotactic with t‐C₄H₉MgBr, syndiotactic with ­t‐C₄H₉Li/R₃Al, and heterotactic with t‐C₄H₉Li/bis(2,6‐di‐t‐butylphenoxy)methylaluminium [MeAl(ODBP)₂]. The last initiator system has been proved effective for monomer‐selective living copolymerization of methacrylates. The living nature of these polymerizations allows extensive use for the syntheses of stereoregular block polymers and copolymers, and end‐functionalized polymers such as macromonomers. Through stereospecific polymerizations and copolymerizations of macromonomers, comb polymers and graft copolymers with defined stereoregularities in the main chain and side chains could be obtained. Some properties of these stereoregular polymers are also described, including stereocomplex formation and solution viscosity. Stereospecific polymerizations of crotonates leading to diisotactic, diheterotactic and disyndiotactic polymers are also discussed. Supercritical fluid chromatography (SFC) has been proven to be useful for isolating uniform polymers from stereoregular poly(methyl methacrylate)s (PMMAs) with narrow molecular weight distribution. Uniform end‐functionalized polymers have been used to construct more elaborate uniform polymer architectures such as stereoblock, star, and comb polymers, and copolymers. The uniform polymers have been proven quite useful for the studies of the relationship between structures and properties such as glass transition temperature, melting temperature and solution viscosity. Particularly interesting is the use of isotactic and syndiotactic uniform PMMAs for the understanding of stereocomplex formation in certain solvents such as acetone. Furthermore, a uniform stereoblock PMMA was found to undergo intramolecular complexation in addition to intermolecular complexation in acetone. Uniform star and comb PMMAs were also prepared and found useful for discussing the effect of branching on the solution viscosity. © 2000 Society of Chemical Industry     

The Effect of Surface Modification of TiO2 with Diblock Copolymers on the Properties of Epoxy Nanocomposites

The TiO₂ nanoparticles were modified by diblock copolymers, poly(methyl methacrylate)-b-polystyrene (PMMA-b-PS), via reversible addition-fragmentation chain transfer (RAFT) polymerization, and the epoxy nanocomposites containing different TiO₂ and with different contents were prepared. Subsequently, the effects of TiO₂ content on the mechanical and thermal properties of nanocomposites were investigated. The results indicated that after grafting copolymers onto TiO₂, the dispersion of TiO₂ and interaction with epoxy matrix could be significantly increased, therefore, the mechanical properties of the nanocomposites were improved greatly. When the TiO₂-PMMA-b-PS content was 1 wt%, the impact strength and flexural strength reached their the best, and increased up to 96% and 43%, respectively. Furthermore, the thermal stability of the nanocomposites was also distinctly improved.