Allylic prepolymers from brassylic and azelaic acids

Diallyl brassylate (DAB), a new monomer, and diallyl azelate (DAA) were converted to new prepolymers for comparison with analogous commercial products from diallyl o-and m-phthalate (DAMP). Respective prepolymers from DAB and DAA had M?_n 28,000 and 40,000 and contained approximately 0.8 free allyl moiety per repeating unit. Only the DAB prepolymer exhibited crystallinity at low temperatures as detected by differential scanning calorimetry and x-ray diffraction. Aliphatic prepolymers have greater heat stability than aromatic ones and evolve fewer calories per double bond during curing than reported for DAMP prepolymer. Low shrinkage (<1%) on curing and clear, hard end products indicate the potential of aliphatic prepolymers as thermosetting plastics. Their liquid state at room temperature should be advantageous in many applications.     

Gas transport properties of polybenzoxazinoneimides and their prepolymers

Three types of imide-containing polyamic acids (polybenzoxazinoneimide prepolymers), namely, a homopolymer, a copolymer, and a polymer-metal complex were synthesized and used for homogeneous membranes preparation. These membranes exhibited good physico-mechanical properties and also chemical and hydrolytical stability. Their gas separation properties were measured and analyzed by correlation with macromolecular packing density. Polybenzoxazinoneimide membranes were prepared by heating prepolymer membranes to 220 °C. Difference between gas separation properties of membranes based on polybenzoxazinoneimides and those of their prepolymers was estimated. Gas transport properties of all novel membranes were compared with those of known membranes by using Robeson's diagram. It was established that a polybenzoxazinoneimide membrane including a polymer-metal complex is the most effective among membranes studied here.     

Syntheses and properties of urethane prepolymers and their corresponding crosslinked films

Trimethylol propane (TMP), polyglycol (PG), and toluene diisocyanate (TDI) were reacted in various molar ratios to produce TMP–TDI–PG–urethane prepolymers and then mixed with equivalent isocyanate generator (Desmodur AP-Stable) in a mixture of m-cresol and naphtha to give polyurethane varnishes which finally became crosslinked films by the casting method. The mechanical properties and viscoelasticities of the PG-modified and PG-free polyurethane crosslinked films and the practicability of magnet wires coated with them were studied in this article. Three different PGs used in this experiment were polyethylene glycol, PEG(#400), polypropylene glycols, PPG(#1000) and PPG(#2000). In the case of adding PEG(#400) for modification, strength at break increased but elongation did not change. Meanwhile, glass transition temperature (T_g) shifted to lower temperature with increasing molar ratio. In the case of adding PPG(#1000) and PPG(#2000) for modification, the samples changed their mechanical properties from hard and brittle to soft and tough. With increasing molar ratios, strength at break initially increased and then decreased gradually, and elongation varied a lot and was consistently contrary to strength at break. T_g occurred at two regions: one at high temperature above 100°C for small molar ratios and the other at low temperature below 100°C for high molar ratios. Besides, for all PG-modified polyurethane crosslinked films, strength at break showed a local maximum at TMP/TDI/PG = 1/1/0.5, which indicated their homogeneous structures. The molar ratios of PG-modified urethane prepolymers, which are suitable for manufacturing practical magnet wires according to testing method JIS-C-3211, are as follows: TMP/TDI/PPG(#100) = 1/1/0.15–0.35 and TMP/TDI/PPG(#2000) = 1/1/0.10. PEG(#400)-modified magnet wires were not accepted on the aging test. The properties of crosslinked films of practical magnet wires are generally as follows: strength at break at 200–700 kg/cm², elongation less than 41%, and T_g at 100–200°C.     

Syntheses and properties of UV-autocurable prepolymers. Semicrystalline urethane-multiacrylates

A series of UV-autocurable urethane-multiacrylate prepolymers, which were semicrystalline and showed melting points in the region of 40–50°C, was synthesized. Also, the effects of curing temperature and acrylic functionality on the structure and properties of the cured films were investigated. These prepolymers are solids and opaque at room temperature. In general, UV curing reactions of solid prepolymers are less efficient when compared with those of liquid prepolymers. UV curing reactions at curing temperatures below the melting point (T_m) of the prepolymers produced semicrystalline urethane-multiacrylate cured films. On the contrary, UV curing reactions above T_m destroyed the crystalline phase of the prepolymers and improved the transparency of the cured films. The films cured below T_m of the prepolymers had higher both breaking strength and Young's modulus, and a higher glass transition temperature (T_g), but a lower elongation at break than those cured above T_m. Such curing temperature effects were attributed to the retention or disappearance of the crystalline structure of the prepolymers during UV curing reaction. At curing temperatures below T_m, an increase in acrylic functionality of the prepolymer resulted in a fast curing rate and a higher crosslinking density of the cured films. Therefore, an increase in acrylic functionality of the prepolymers gave cured films with higher breaking strength and Young's modulus, but a lower elongation at break.     

Allylic polymers from resin acids. Monomer synthesis at high temperature

New chemical compounds, i. e. ketones of the abietic acid-diallyl maleate Diels-Alder adduct, have been synthesized when the reaction of abietic acid and diallyl maleate was carried out at high temperatures (up to 250°C). Having unsaturated groups in their structure, they are polymerizable substances. The monomers and the polymers have been investigated by commonly used chemical and physical methods. The polymers are soluble in polar organic solvents only at low molecular weights. The behavior of these compounds as crosslinking monomers in copolymer systems has been examined.     

Preparation and characterization of bismaleimide-diamine prepolymers and their thermal-curing behavior

Various bismaleimide-diamine Michael addition type prepolymers were prepared through melt condensation and using acetone, dimethylformamide, and m-cresol as solvents in a molar ratio of 1 : 1. Structures of the prepolymers, such as terminal moieties and molecular weight of main chain, depended strongly on the preparation conditions used. More terminal double bonds were observed in the molecule of the prepolymer (sample 3) prepared in dimethylformamide solution without a catalyst. In contrast, the prepolymer produced in m-cresol solution had a polyaspartimide structure with a higher molecular weight. The differential scanning calorimetry and Fourier transform infrared spectra results demonstrated that the molecular structure of the prepolymer had a noticeable effect on their thermal-curing behavior. Thermal properties (T_g and T_d) of cured polymers were evaluated. The polyimide (sample 3b) from sample 3 exhibited the highest T_g and but still retained very good processing properties for film casting. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2471–2477, 1998     

Organometallic polymers. V. Synthesis and properties of metallocene-modified polymers

The reaction of metallocenes with solutions of polydienes and halogenated polymers, under Friedel-Crafts conditions, has now been applied to the surface modification of solid polymer films. The reaction of ferrocene with chlorinated polyethylene films appears to proceed by a fast substitution step followed by a slower diffusion-controlled step. The stress–strain curves of surface-modified films, as well as of solution-cast polymetallocene films, have been examined by means of a bursting-strength apparatus. The weathering behavior of metallocene-modified polymers has been studied in both natural and accelerated conditions. Studies on the effect of ageing on composition and properties by spectrophotometric and mechanical measurements indicate that the photooxidative resistance of polymers is improved significantly by metallocene modification. Additionally, modified films have been found to be effective as clear shields for the protection of vulnerable substrates against photodegradation. The observed darkening of the irradiated films could be due to a thermal reaction between metallocene and photolytically generated macroperoxides.     

双亲聚合物的合成及其溶液性质的研究进展

综述了双亲聚合物的合成方法,包括经典自由基聚合法、活性离子聚合法、"活性"/可控自由基聚合法及其他方法,着重介绍了近年来才兴起的"活性"/可控自由基聚合法;简要介绍了有关其溶液性质的研究,包括双亲聚合物在选择性溶剂中的胶束化行为,其胶束的增溶作用,并介绍了双亲聚合物在固/液、气/液界面的吸附行为.最后,对双亲聚合物今后的发展方向进行了展望.     

Syntheses and properties of pentaerythritol-containing urethane prepolymers and crosslinked films

Two series of polyhydroxyl urethane-prepolymers (Pre-PU) were synthesized from pentaery-thritol (PETH), toluene diisocyanate (TDI), and polyglycols (PG). One is a single molecular type of PETH-(TDI-PG)_n-TDI-PETH Pre-PU (S-Pre-PU). The other is a mixture of (PETH-TDI)_n-PETH and S-Pre-PU. The Pre-PU mixed with an equivalent triisocyanate regenerator (Desmodur AP-Stable, a crosslinking agent) were baked to form the crosslinked PU films. The mechanical properties such as tensile strengths, elongation at break, and viscoelasticities of PG-modified crosslinked films were studied.     

Synthesis and properties of 5-substituted 2-thiobarbituric acid dyes

The systematic synthesis of 5-substituted 2-thiobarbituric acid dyes (5-p-methoxy- and 5-p-dimethylamino-benzylidene-, cinnamylidene-, and phenylpentadienylidene-1, 3-disubstituted 2-thiobarbituric acids) is described and their absorption characteristics are reported.     

Antimony polymers,part 2. Physical,chemical and thermal properties

Three antimony-containing polymers (P₁, P₂, P₃) were synthesized by reacting triphenyl antimony dinitrate with bisphenol A (P₁), with tetrabromobisphenol A (P₂) and with N,N′-bis(4-hydroxybenzylidene)-oxydianiline (P₃). Solubility, density, chemical and thermal stability of these antimony polymers have been evaluated. The polymers are only soluble in dipolar aprotic solvents like dimethyl sulfoxide, dimethylformamide, dimethylacetamide, etc., and have relatively high densities (1.2–1.8 g cm^–3). The solubility parameters (δ) and chemical stability of the polymers were studied in different chemical environments. The thermal properties of the polymers have been studied by thermogravimetric analysis, differential thermal analysis and isothermal gravimetric analysis.     

Preparation and photophysical properties of organic fluorescent polymers and their nanoparticles

New classes of stable organic florescent polymer nanoparticles were prepared from the corresponding tetrahydrofuran (THF) solutions, upon slow evaporation of solvent under a mild vacuum. Uniform spherical nanospheres having mean diameter of ? 500–700 nm, showed enhanced fluorescence emission in solution, but it diminished when it is destroyed using an organic base. These end‐capped fluorescent polymers are highly stabilized in the excited states at higher concentration in solution, leads no more intra‐ and intermolecular interactions among the excited molecules, because of the absence of free functional groups. The significant enhancement in fluorescence emission was attributed to the high level of molecular stacking in the fluorescent nanoparticles, when compared with micron‐sized isolated powder sample. In addition, these fluorescent polymers exhibited significant thermal properties, along with better solubility in most of common organic solvents for their future application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5344–5350, 2006     

Synthesis of azobenzene-functionalized star polymers via RAFT and their photoresponsive properties

Azobenzene-functionalized star polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. First, azobenzene-functionalized linear macro chain transfer agents (Macro-CTA) were synthesized by RAFT polymerization of 6-[4-(4′-Methoxyphenylazo)phenoxy]hexylmethacrylate (MAz6Mc) using 2-(2′-cyanopropyl)dithiobenzoate (CPDB) as RAFT agent in presence of AIBN as initiator in anisole. Subsequently, star azopolymers were synthesized by polymerization of a difunctional azomonomer, BMA2Az, with resultant Macro-CTA in presence of AIBN as initiator in anisole. Star azopolymers were characterized by GPC and spectroscopic methods. Thermal properties of star azopolymers were determined by DSC and TMA. Molecular weight versus conversion and molecular weight versus polymerization time attest to living polymerization characteristics. Photoisomerization behaviors of star azopolymers were studied by irradiation of both UV and visible light. Surface relief gratings were inscribed on star azopolymer films upon exposure to an interference pattern of (RCP + RCP) Ar⁺ laser. A diffraction efficiency of 20% was obtained by exposure of Star-8 K(2.6 K) polymer film to an (RCP + RCP) Ar⁺ laser for about 30 min. Surface relief grating structures were investigated by AFM and polarized optical microscopy.     

Synthesis and properties of prepolymers and their siloxane analogues by thiol‐ene polyaddition of limonene with dithiols

This work presents a synthesis of monomers from a natural compound (limonene) and dimethylsiloxanes with various chain lengths by hydrosilylation. Based on these monomers, prepolymers with various lengths of the siloxane and methylene parts, as well as their analogues without siloxane moieties, were obtained by thiol‐ene polyaddition with ethanedithiol, butanedithiol and hexanedithiol. Their physicochemical characteristics, namely the thermal stability, phase behaviour and intrinsic viscosity of the polymers obtained, were compared as a function of the length of the methylene spacer and the siloxane part in the polymer chain. © 2019 Society of Chemical Industry     

聚丁二酸丁二醇酯的合成及性能研究

选取钛酸四正丁酯(TBT)和二(乙酰丙酮)钛酸二异丙酯(DIPEAT)单独或复配作为催化剂,采用直接酯化-缩聚法,合成聚丁二酸丁二醇酯(PBS),研究了TBT,DIPEAT,TBT-DIPEAT(摩尔比1∶1)3种催化剂对缩聚反应速度及合成产物的物理性能、热稳定性和流变性能的影响。结果表明:3种催化剂的催化活性由高到低依次为TBT,TBT-DIPEAT,DIPEAT;DIPEAT催化合成的PBS的相对分子质量分布较窄,物理性能较好;相比TBT催化剂,DIPEAT催化合成的PBS的热稳定性较好,PBS失重5%时热分解温度提高约12℃;以TBT,DIPEAT或TBT-DIPEAT作为催化剂,得到的PBS的流动曲线相似,熔体的表观黏度随着剪切速率的增大而减小,随着温度升高而降低,都是切力变稀型非牛顿流体。     

Synthesis and three dimensional pattern finishing properties of blocked isocyanate prepolymers

Two kinds of blocked isocyanate prepolymers (BIPs), BIP-S and BIP-H, were synthesized, and three dimensional pattern (3D) finishing properties of BIPs were investigated with several techniques. As a result, the BIP-H exhibited higher glass transition temperature, tensile strength, and tensile modulus than did BIP-S. The combination of two kinds of antioxidants resulted in good performance that prevented yellowing at high temperature and exposure to sunlight. 3D pattern finished cotton fabrics coated with BIP-S showed a higher transparency than that of non-coated cotton fabrics. Both cotton fabrics coated with BIP-S and those coated with BIP-H showed excellent repellency to alkali solution.     

Effect of hydrostatic pressure and temperature on the mechanical loss properties of polymers: 2. Halogen polymers

The shear modulus, G′, and loss tangent, tan δ, of a number of halogen polymers have been measured as a function of temperature at various pressures. The polymers studied were various poly(vinyl chloride) (PVC) samples, poly(vinylidene chloride) (PVDC), poly(vinyl fluoride) (PVF), poly(vinylidene fluoride) (PVDF) and a tetrafluoroethylene-hexafluoropropylene copolymer. The glass transition temperatures are shifted upwards by pressure by amounts varying between about 11°C and 25°C/1000 atm. In the case of PVC it has proved possible to compare the results with theory and the observed shift is found to be considerably smaller than the predicted value. In PVDC and PVDF the secondary relaxations are also shifted upwards by the application of pressure.     

Conducting polymers of terepthalic acid bis-(2-thiophen-3-yl-ethyl) ester and their electrochromic properties

Terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester (TATE) was synthesized through the reaction of 2-thiophen-3-yl-ethanol and terepthaloyl chloride. Homopolymer of TATE was synthesized via potentiostatic and potentiodynamic methods by using tetrabutylammonium tetrafluoroborate (TBAFB) as the supporting electrolyte in dichloromethane/borontrifluoride ethylether solvent mixture (DM/BFEE) (8:2, v/v). Copolymerisation of TATE with thiophene was achieved in DM/BFEE solvent mixture (8:2, v/v) by using TBAFB as the supporting electrolyte in the presence of thiophene. The chemical structure of monomer is characterised via NMR and FTIR. Both homopolymer (PTATE) and copolymer P(TATE-co-Th) were characterised by various techniques including cyclic voltammetry, FTIR, scanning electron microscopy and UV-VIS spectroscopy. Conductivities of samples were measured by four probe technique. Optoelectrochemical analysis indicates that the homopolymer and copolymer have an electronic band gap, measured as the onset of the π-to-π* transition, as 2.17 and 2.00 eV, respectively.     

Synthesis,crosslinking, and characterization of energetic polymers through the azidification of glycidyl ether prepolymers

Low‐molecular‐weight atactic poly(propylene oxide) and poly(epichlorohydrin) (PECH) were chlorinated on average up to 4.42 chlorine atoms per repeat unit. A study of the products showed that chlorine substitution preferentially occurred on already chlorinated repeat units, yielding chlorine ‐rich and chlorine ‐poor sequences. As the extent of chlorine substitution increased, the glass‐transition temperature of the polymers markedly increased, and their solubility in most of the organic solvents drastically decreased. The chlorinated polymers were azidified with NaN₃ in dimethyl sulfoxide solutions. An analysis showed that azide groups replaced 99.8–99.9% of the initially present chlorine atoms. As the azide content of the samples increased, initially opaque polymers become dark brown, and their solubility increased in water but decreased in organic solvents. Samples with approximately four or more azide groups per repeat unit were only soluble in dimethyl sulfoxide and water. The standard enthalpy of formation of the polymers became increasingly positive as the azide content increased. The enthalpy of formation of a sample with 4.42 N₃/repeat unit was 6929 kJ/repeat unit, whereas this value was only 103 kJ/mol for classical GAP. An azidified sample from PECH (4.42 N₃/repeat unit) was crosslinked with a commercial triisocyanide into a rubbery product. The density and ultimate tensile strength of the rubbery product were 1.44 g/cm³ and 4.84 MPa, and it swelled about 10% at 20°C in water.© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3785–3790, 2004