Low surface energy films based on partially fluorinated isocyanates: the effects of curing temperature

Self-stratification strategy can be used to prepare films in which both bulk and surface properties can be optimized. By using this approach, only a very small quantity of fluorinated species is needed to generate a surface with low surface energy. When cross-linking is involved during film formation, we are dealing with a competition behavior between the diffusion of fluorinated species and the formation of cross-linked network. In this study low surface energy polymeric films were prepared on the basis of partially fluorinated polyisocyanates, in combination with hydroxyl-end-capped three-armed solventless liquid oligoesters and modified hyperbranched polyesters. At a fluorine concentration of only 0.5 wt.%, contact angles of water and hexadecane can reach 120° and 80°, respectively. A surface energy as low as 10–15 mN/m can be obtained upon the addition of less than 1 wt.% of fluorine in the films. It was shown, from real time ATR-FTIR and contact angle measurements, that the curing temperatures demonstrated significant effects on the cross-linking rate as well as on the wettability of the films.     

Synthesis and self-assembly of hyperbranched polyester peripherally modified by touluene-4-sulfonyl groups

In this paper, hyperbranched polyesters (HPs) were synthesized in the molten state from 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) and 2-ethyl-2-hydroxymethyl-1,3-propanediol (TMP) using acid catalysis. The modified hyperbranched polyesters were obtained through the chemical modification of the hyperbranched polyester cores by substituting a controlled fraction of the terminal hydroxyl groups with touluene-4-sulfonyl chloride using triethylamine (TEA) as an acceptor of HCl. The resultant polyesters were characterized by ¹H NMR, ¹³C NMR, FT-IR, UV and GPC and their self-assembly behaviors were investigated. The results revealed that self-assembled structures could be formed in selected solvents (trichloromethane/acetone or trichloromethane/n-hexane).     

Gas transport properties of 6FDA-TAPOB hyperbranched polyimide membrane

Physical and gas transport properties of the hyperbranched polyimide prepared from a triamine, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), and a dianhydride, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), were investigated and compared with those of linear-type polyimides with similar chemical structures prepared from diamines, 1,4-bis(4-aminophenoxy)benzene (TPEQ) or 1,3-bis(4-aminophenoxy)benzene (TPER), and 6FDA. 6FDA-TAPOB hyperbranched polyimide exhibited a good thermal stability as well as linear-type analogues. Fractional free volume (FFV) value of 6FDA-TAPOB was higher than those of the linear-type analogues, indicating looser packing of molecular chains attributed to the characteristic hyperbranched structure. It was found that increased resistance to the segmental mobility decreases the gas diffusivity of 6FDA-TAPOB, in spite of the higher FFV value. However, 6FDA-TAPOB exhibited considerably high gas solubility, resulting in high gas permeability. It was suggested that low segmental mobility and unique size and distribution of free volume holes arising from the characteristic hyperbranched structure of 6FDA-TAPOB provide effective O₂/N₂ selectivity. It is concluded that the 6FDA-TAPOB hyperbranched polyimide has relatively high permeability and O₂/N₂ selectivity, and is expected to apply to a high-performance gas separation membrane.     

Synthesis of new hyperbranched urethane-acrylates and their evaluation in UV-curable coatings

Three series of hyperbranched urethane-acrylates (HB-UA), based on aliphatic hyperbranched polyesters and polyethyleneglycol acrylate, were prepared and evaluated for use in UV-curable coatings. UV-curing kinetics were monitored by FT-IR spectroscopy. The thermal and mechanical properties of UV-cured HB-UA were investigated by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and correlated to the mechanical properties of coatings (hardness and flexibility). These new HB-UA's are very reactive and did not show oxygen inhibition. Obtained coatings have good mechanical properties and solvent resistance.     

超支化聚合物用于材料制备和改性的研究

综述了近年来超支化聚合物在聚合物增韧、增塑、粉体填料的表面改性以及制备纳米粒子和纳米复合材料等方面的研究进展。     

Biodegradable and thermostable synthetic hyperbranched poly(urethane-urea)s as advanced surface coating materials

Aliphatic hyperbranched poly(urethane-urea)s with different weight percentages of branch generating moiety were synthesized by a one pot A₂ + BC₂ approach. Isophorone diisocyanate was used as the A₂ type monomer, while a tri-functional dihydroxyamine compound synthesized from ?-caprolactam and diethanol amine acted as the BC₂ monomer. Evidence supporting the hyperbranched structure of the synthesized poly(urethane-urea) was obtained from ¹H NMR spectra. FTIR study confirmed the nature and extent of hydrogen bonding present in this novel macromolecule. A Gaussian band fitting procedure of the IR band at amide-I region showed that the extent of hydrogen bonding increases with the increase of weight percentage of the tri-functional compound. The tensile strength, elongation at break, impact resistance, scratch hardness and gloss followed an increasing trend with the same. The thermal degradation of the hyperbranched poly(urethane-urea) was found to be dependent on the weight percentage of the BC₂ type moiety. The kinetics of thermal degradation studied by the Ozawa method showed that the activation energy required for thermal degradation of hyperbranched polymer is higher than its linear polyurethane analog. The synthesized polymer was found to be biodegradable by Pseudomonas aeruginosa bacteria. The study showed superiority of the hyperbranched structure over the linear one. Thus the results indicated the potential usage of the studied hyperbranched poly(urethane-urea) as an advanced surface coating material.     

Phosphorus based indole and imidazole functionalized hyperbranched polyester as antimicrobial surface coating materials

Third generation of hyperbranched polyester (HP) synthesized via melt condensation and end-capped with bis indole and imidazole phosphoryl chloride. The modified polyesters subjected to different characterization viz., FTIR, ¹H and ¹³C NMR, GPC and elemental analysis. NMR analysis was used for the determination of OH conversion that demonstrates linear units had a lower reactivity as compared to terminal OH groups in HP. The thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) studies indicated that the HP was stable up to 276 °C and the glass transition temperature was 79.6 °C. After modification of HP, thermal stability was increased for indole modified HP, but the glass transition temperature was decreased. The flame retardance of the hyperbranched polyester was also evaluated with the help of TGA analysis and showed higher value of limiting oxygen index (LOI) for modified polyesters. Morphology of the modified polyester showed more roughness than unmodified HP and this nature positive correlated with bacterial zone of inhibition value. Biological studies showed that the HP and modified HP are able to inhibit the reproduction of gram-positive and gram-negative bacteria. Indole modified HP is showed good activity compared to imidazole modified HP.     

超支化压裂液稠化剂的制备及评价

以二乙醇胺（DEA）、丙烯酸甲酯（MA）、三羟甲基丙烷（TMP）、顺丁烯二酸酐（MAH）为原料，合成了一种端羧基超支化大单体HPAE-C。并以HPAE-C、丙烯酰胺（AM）、丙烯酸（AA）以及2-丙烯酰胺基-2-甲基丙磺酸（AMPS）为单体，在水溶液中进行自由基聚合得到一种四元共聚物稠化剂PHPAE-C。通过FTIR和1HNMR对其结构进行表征。评价了超支化稠化剂的溶液性质和交联性能。结果表明，稠化剂质量浓度为3000 mg/L（剪切速率为7.34 s-1，25℃）时，溶液表观黏度可达846.7 mPa·s，升温至90℃时，黏度仍为570 mPa·s，并且在Na+质量浓度为6000 mg/L、Ca2+和Mg2+质量浓度为600 mg/L时表观黏度仍能达到300mPa·s以上，说明PHPAE-C具有良好的增黏、耐温、耐盐和抗剪切性能；在交联比m(聚合物水溶液)∶m(乙酰丙酮锆)=100∶0.06、交联温度为55 ℃、pH=5时交联效果最佳。并对交联效果最佳的压裂液进行了性能评价，结果表明，在120℃、170s-1下剪切80 min后，该体系的表观黏度可达到450 mPa·s左右，并且是一种具有良好悬砂、破胶性能的低伤害压裂液体系。     

Flame retardancy and thermal property of novel UV-curable epoxy acrylate coatings modified by melamine-based hyperbranched polyphosphonate acrylate

A novel melamine-based hyperbranched polyphosphonate acrylate (MHPA), successfully synthesized via the Michael addition polymerization of 2-(2-amino-ethylamino)-4,6-bisethylamino-1,3,5-triazine with tri(acryloyloxyethyl) phosphate, was blended with the epoxy acrylate (EA) to prepare UV-cured flame retardant coatings. The study of their flammability revealed that MHPA can improve the flame retardancy and the sample with 45 wt% MHPA (EA3) showed a good intumescent behavior when combusted. The results of their thermal degradation displayed that MHPA had a dual effect on the thermal stability of EA: leading to its earlier degradation catalyzed by acidic species from the relatively weak phosphorus-bearing parts, but improving the thermal stability of the char layer at high temperature due to the formed intumescent phosphorus–carbon compounds. Besides, the total release amount of gas products of EA3 was much lower than that of pure EA and various flammable gases like hydrocarbons and highly toxic CO were also reduced     

Theoretical investigation on the polyaddition of A2 and CB2 monomers with non-equal reactivity

Taking account of the difference of reactivities between C and B group, the evolution of the monomers and the various structural units formed from the polyaddition of A₂ and CB₂ monomers was investigated by the kinetic mechanism. The calculated results theoretically explain the experimental data observed in our previous works very well, if the reactivity ratio of C to B groups is 200. The critical conversion of gelation for the A₂ + CB₂ type polymerization depends on the reactivity ratio. The lower the ratio, the earlier the gelation appears. Compared with the A₂ + B₃ type polymerization, the disappearance of gelation for the A₂ + CB₂ type polymerization should attribute to the much higher reactivity of C group than that of B one. The analytical expression of the degree of branching was derived as well. If the reactivity of C group is much higher than that of B group and the substitution effect is neglected, the value of the degree of branching for the hyperbranched polymers obtained is equal to the value of conversion of B groups and it may exceed 0.5, with the feed ratio of monomers varying from 1 to 3/2.