Synthesis,characterization, and kinetic study of functional polystyrenes

In this study, functionalization of polystyrene (PS) (M_n = 2.5 × 10⁵) was carry out with maleic anhydride in the presence of boron trifluoride dietyhletherade (BF₃ OEt₂) as catalyst and then functional PS was subjected to condensation reaction with phenyl hydrazine. The structures of both of them were determined by using FTIR, ¹H‐NMR, elemental analysis, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. Some physical properties of these two products were investigated and the kinetic parameters of solid state decomposition reactions were determined from TGA curves. The intrinsic viscosity [η] values of modified PS and condensation products (cPs) found to be 1.024 and 0.7036 dL g^?1, respectively. According to TGA, the weight losses of modified PS and cPs were found to be 84.03 and 81.86%, respectively, at 500°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Melt grafting of 10‐undecenoic acid onto linear low density polyethylene

The melt grafting of 10‐undecenoic acid (UA) onto a linear low‐density polyethylene (LLDPE) was studied. The grafting reaction was performed in a thermoplastic mixer and 2,5‐dimethyl‐2,5‐di(tert‐butylperoxy) hexane was used as initiator. The concentration of UA and peroxide ranged from 1 to 4% (w/w) and 0.025 to 0.1% (w/w), respectively. Evidence of the grafting of UA as well as its extent was determined by FTIR. Experimental results showed that the amount of UA grafted increases with both the UA and initiator concentrations. However, the greatest efficiency of grafting was found at the lowest concentration of UA investigated. The grafting efficiency ranged from 8 to 40%. The dynamic linear viscoelastic properties of the original polymer and the grafted materials were evaluated at different frequencies at 160°C using a dynamic rotational rheometer. The modification process affected the melt elasticity and viscosity of the LLDPE. When the original polymer was modified only with peroxide both properties increased with respect to those of the original material. However, when UA was grafted onto LLDPE, the resulting polymers displayed values of elastic moduli and viscosity lower than those of the polymer modified with peroxide. Moreover, when a concentration of 4% of UA was used, the values of those properties were even lower than those corresponding to the original LLDPE. These observations combined with the data obtained from the GPC results suggest that scission reactions may be favored by the presence on UA. In contrast with previous observations, the thermal properties measured by DSC were only slightly altered. The fusion temperature of the modified polymers was slightly lower than that corresponding to the original polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2303–2311, 2004     

Synthesis and characterization of a drug‐delivery system based on melamine‐modified poly(vinyl acetate‐co‐maleic anhydride) hydrogel

Three‐dimensional polymeric networks, which quickly swell by imbibing a large amount of water or deswell in response to changes in their external environment, are called hydrogels. These types of polymeric materials are good potential candidates for drug‐delivery systems. In this study, we first synthesized poly(vinyl acetate‐co‐maleic anhydride) by free‐radical copolymerization. Then, they were modified with different molar ratios of melamine to prepare hydrogels that could be used in drug‐delivery systems. The hydrogels were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, differential scanning calorimetry, and scanning electron microscopy. In the second step, Ceftazidime antibiotic was loaded on selected hydrogels. The in vitro drug release was investigated and compared in three different media (HCl solution at pH = 3 and buffer solutions at pH 6.1and pH 8). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40389.     

悬浮聚合法制备亲水-亲油型高分子固相萃取填料及其功能化研究

采用悬浮聚合法合成了一种以二乙烯苯和N-乙烯吡咯烷酮为单体的高分子聚合物固相萃取填料(DVB-NVP),系统地考察了引发剂、致孔剂、分散剂以及反应时间等对填料形态和粒径分布的影响,用光学显微镜对其进行表征,以农药作为模型化合物,结合紫外分光光度(UV)和高效液相色谱法(HPLC)对填料进行评价。同时对合成的微球进行官能团衍生,并优化衍生化条件。结果表明:以羟丙基甲基纤维素为分散剂,偶氮二异丁腈为引发剂时,于80℃下反应8h可制得粒径为20~60μm的单分散高交联亲水-亲油型聚合物,其对灭多威、福美林以及乙酰甲胺磷的回收率分别为97.34%、86.24%和96.96%,相对标准偏差分别为2.27%、0.96%、1.83%。4种衍生化DVB-NVP填料具有较高的离子交换容量。     

Building of a sulfonyl‐group‐functionalized monomer whose polymer is able to catalyze biodiesel formation

A linear polymer containing sulfonyl groups was synthesized from a vinyl monomer to use its acid group as a catalyst of the esterification of oleic acid to form biodiesel. First, synthesis optimization of the monomer was carried out in an aqueous system. This molecule was obtained in an excellent yield, where the pH and reaction time were decisive factors in the synthesis performance. The vinyl monomer was then polymerized, and the catalytic activity of the sulfonic acid could be demonstrated in the esterification of oleic acid with short‐chain alcohols. The increase in the catalyst content resulted in a higher concentration of the carbonyl group activated, and this was followed by faster esterification kinetics. The highest yield (98 mol %) was reached after 20 min when a 10 mol‐% of catalyst was used. A larger size alcohol led to slower esterification kinetics because its ability as a nucleophile was decreased by steric impediment. The sulfonyl group in polymer 4 , an aryl sulfonic acid polymer, proved to be an acid almost as efficient as sulfuric acid, although the former worked in a heterogeneous system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41957.     

聚(3-羟基丁酸-co-4-羟基丁酸酯)/碳纳米管复合微孔发泡薄膜研究

用红外(FT-IR)谱、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和差示扫描量热仪(DSC),研究了多壁碳纳米管(MWCNT)分别在强酸和偶氮二异丁腈(AIBN)+过氧化二苯甲酰物(BPO)中的表面修饰过程,并将其与聚(3-羟基丁酸-co-4-羟基丁酸酯)/碳纳米管复合,制备了微孔发泡薄膜,孔径最大50μm,最小10μm。结果表明,在相同溶剂条件下,偶氮二异丁腈+过氧化二苯甲酰可以成功地实现碳纳米管的表面修饰,修饰后的碳管浓度为1%(质量分数)与聚合物较好相容,当其比例为1∶2、1∶1时分别获得"莲蓬型"和"蜂窝型"微孔发泡结构薄膜,并具有较好的导电性。     

应力诱导引发MAH官能化PE-LD及其对铝箔/PET复合薄膜层间剥离强度的影响

采用提高双螺杆挤出机螺杆转速的应力诱导引发方法和添加引发剂与提高螺杆转速的复合引发方法,研究了高剪切应力作用下马来酸酐(MAH)与低密度聚乙烯 (PE-LD)的官能化反应,并且考察了官能化产物PE-LD-g-MAH对铝萡/PET薄膜（Al/PET）热熔胶的T型黏合接头剥离强度的影响。结果表明,高剪切应力作用可直接引起大分子链的断链,形成大分子自由基,引发PE-LD的接枝反应;通过改变螺杆转速可有效抑制交联副反应,制得具有较高接枝率、较好熔体流动速率和较低凝胶含量的官能化产物,当螺杆转速为800 r/min时,产物的接枝率为0.71 %,熔体流动速率为0.87 g/10 min,凝胶含量0.40 %;高剪切应力诱导引发法所得官能化产物可明显提高Al/PET热熔胶T型黏合接头的剥离强度,当反应温度为310 ℃,螺杆转速为600 r/min,三元乙丙橡胶（EPDM）含量为80 %（质量分数,下同）时,可使Al/PET的T型黏合接头的剥离强度达3.87 N/mm。     

Functionalization of polymethylhydrosiloxane gels with an allyl ureido benzocrown ether derivative: Complexation properties

Crosslinked polymethylhydrosiloxane (PMHS) thin films prepared by sol–gel polycondensation have been functionalized by Pt‐catalyzed hydrosilylation of SiH groups with an allyl ureido crown ether precursor. To this purpose, both 4′‐allylurea‐benzo‐15‐crown‐5 ( 1 ) and 1‐allyl‐3‐propyl‐urea ( 2 ) were synthesized and characterized. We have shown that competitive side‐reactions occurred following hydrosilylation due to the hydrolysis of part of the SiH groups resulting in the formation of new crosslinks Si(CH₃)O_3/2 as shown by solid‐state ²⁹Si‐NMR. This is explained by the deactivation of the Pt catalyst toward hydrosilylation by amide groups. For thin films (～ 1 μm) prepared on silicon wafers, a quantitative method based on FT‐IR transmission spectroscopy was used to measure the crosslinking density of the network, and the percentage of functionalization (SiC %) following hydrosilylation. The results are discussed in relation to the mesh size of the network, and the diffusion of alkenes and water molecules within lightly crosslinked PMHS gels obtained by varying the amount of triethoxysilane crosslinker (mol %) from 15 to 1%. The self‐organization properties of ureido groups by H‐bonding were studied by FT‐IR for the functionalized thin films. The complexation properties of the crown ether 1 ‐functionalized thin films were evidenced by using FT‐IR following diffusion‐reactions of NaSCN and KSCN salts in CHCl₃ : MeOH solvent mixtures within thin films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009