Synthesis of New Reactive Polyethers: Poly(-bromoalkyl-1-glycidylether)s

Serra

2001

Macromol. Chem. Phys.

A new class of liquid‐crystalline epoxy resins containing azomethine and azo groups was synthesized and structurally characterized. The liquid crystal behavior of these compounds was characterized by differential scanning calorimetry (DSC), hot‐stage polarized optical microscopy (POM) and wide‐angle X‐Ray diffraction (WAXS). An aliphatic spacer between the mesogenic aromatic central core and the glycidyl groups favors the formation of different types of smectic mesophases with a wide range of stability. The LC resins were cured to obtain liquid crystal thermosets (LCTs). The cure was tested using aromatic primary diamines as curing agents and nematic‐like networks were obtained. When tertiary amines were used catalytically, smectic C‐like networks were retained when the spacer length had four methylene units or more. The polydomain ordered materials obtained were characterized by WAXS and their thermal stability was tested by thermogravimetric analysis (TGA).

“…[16] The synthesized products were recrystallized and characterized by means of spectroscopic techniques. Figure 1 shows the 1 H-NMR spectrum of the glycidylic compound M4.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of New Epoxy Liquid-Crystalline Monomers with Azo Groups in the Central Mesogenic Core. Crosslinking with Amines

Castell

Serra

2001

Macromol. Chem. Phys.

“…The diglycidylic compounds of the A n series, with flexible spacers, were synthesized by the nucleophilic displacement of bromine on the corresponding ω‐bromoalkylglycidyl ether in the presence of potassium carbonate and 18‐crown‐6 as a catalyst. ω‐Bromo‐1‐alkylglycidyl ethers were synthesized from 1,ω‐alkanediols with a reported procedure 19…”

Section: Resultsmentioning

confidence: 99%

“…ω‐Bromo‐1‐alkanols were synthesized from the corresponding diol and hydrobromic acid. ω‐Bromoalkylglycidyl ethers were synthesized through the reaction of ω‐bromo‐1‐alkanols and epichlorohydrin with boron trifluoride etherate as a catalyst according to a reported procedure 19…”

Section: Methodsmentioning

confidence: 99%

Liquid‐crystalline thermosets from liquid‐crystalline epoxy resins containing bisazomethinebiphenylene mesogens in the central core: Copolymerization with a nonmesomorphic epoxy resin

Castell

Serra

J. Polym. Sci. A Polym. Chem.

2004

A new series of liquid‐crystalline epoxy resins was synthesized, and their mesomorphic behavior was investigated with differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray scattering. These glycidylic compounds had central aromatic imine mesogens derived from benzidine and aliphatic spacers of up to 10 methylene units that linked the mesogens to the glycidylic groups. Crosslinking these monomers with primary aromatic diamines led to nematic networks, some of which contained crystal inclusions. However, through curing with tertiary amines as catalytic agents or through copolymerization with different proportions of the nonmesomorphic epoxy monomer and primary amines as crosslinking agents, smectic C organized thermosets were prepared when the spacers had at least four methylene carbons. When they had fewer than four, the networks were nematic. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3631–3643, 2004

“…[17] The most general method is the continuous extraction of a mixture of diol and hydrobromic acid with a non polar solvent, in the conditions described in the experimental section (molar ratio diol/HBr 1 : 4, 80 8C and 20 h). [18] The next step was to synthesize (6-bromo-1-hexyl) glycidyl ether. The synthetic procedure had to give products that are free of protic impurities since the monomers are going to be polymerized using coordinative catalysis.…”

Section: Polymerization Of Epibromohydrin and (6-bromo-1-hexyl) Glycimentioning

confidence: 99%

“…[20] Recently, various x-bromoalkyl glycidyl ethers had given good polymerization results with this Vandenberg catalyst: polymer conversions and molecular weights are high while polydispersity was relatively low. [18] Polymers were characterized by IR, 1 H NMR and 13 C NMR techniques, which showed the expected signals for a polyether with a pendant bromoalkyl side chain. The T g values of these polymers were determined by DSC.…”

Section: Polymerization Of Epibromohydrin and (6-bromo-1-hexyl) Glycimentioning

confidence: 99%

Synthesis and Crosslinking of Polyethers with Ethynylphenyl Pendant Groups

Ribera

Cádiz³

2001

Macromol. Chem. Phys.

Polyepibromohydrin (A) and poly[(6‐bromo‐1‐hexyl) glycidyl ether] (B) were synthesized from precursor monomers using a coordinative ionic catalyst. These brominated polymers were chemically modified using 1,8‐diazabicyclo[5.4.0]‐7‐undecene to catalyze the substitution of the bromine atom by p‐ethynylbenzoic acid. A quantitative modification was reached. Linear polyethers with ethynyl side chain undergo a process of thermal crosslinking that leads to thermostable polymers. Isoconversional kinetic analysis was applied to DSC data and the dependencies of the activation energies on the conversion degrees were obtained. The degree of modification was shown to influence the crosslinking process.