A Novel Copolymer: Starch‐g‐Polyvinylpyrrolidone

In this study, graft copolymerization of N‐vinylpyrrolidone (N‐VP) onto starch was carried out in an aqueous medium using azobisisobutyronitrile (AIBN) as initiator. The variables affecting the graft copolymerization, such as monomer and initiator concentrations, reaction time and temperature, were thoroughly examined. In general, grafting of N‐vinylpyrrolidone onto starch increased with the increase in time and monomer concentration up to a certain value and then leveled off. Similarly, increase both in initiator concentration and temperature first favored and than impeded the grafting reaction. Optimum conditions established for grafting were as follows: N‐VP = 0.7 M, AIBN = 1.5×10^‐3 M, T = 70°C and t = 5 h. Structural changes of the grafted starch were followed by FTIR, intrinsic viscosity and water absorption capacity studies.     

马铃薯淀粉与醋酸乙烯酯接枝聚合影响因素的研究

以马铃薯淀粉为接枝骨架,过硫酸铵为引发剂,醋酸乙烯酯(VAc)为接枝单体进行接枝共聚。考察了不同引发剂浓度、反应温度、反应时间、单体配比、淀粉浓度对单体转化率、接枝率及接枝效率的影响,确定最佳工艺条件为:引发剂浓度18 mmol/L,反应温度60℃,反应时间3.5 h,单体配比2.5:1,淀粉浓度5%。并通过扫描电镜,X射线衍射,傅里叶红外光谱对淀粉接枝共聚物进行分析,结果表明:淀粉接枝共聚后,淀粉的微观形貌已经改变,结晶度降低且醋酸乙烯酯成功接枝在马铃薯淀粉上。     

Grafting of 2‐(Dimethylamino)ethyl Methacrylate onto Potato Starch Using Potassium Permanganate/Sulfuric Acid Initiation System

Graft copolymerization of 2‐(dimethylamino)ethyl methacrylate onto potato starch was carried out in an aqueous medium using a potassium permanganate/sulfuric acid initiation system. The grafting percentage and grafting efficiency were determined as functions of the concentrations of potassium permanganate, sulfuric acid and the monomer, and also polymerization temperature and time. The IR spectrum of the graft copolymer showed the peaks characteristic of the grafted chains. The grafting percentage and grafting efficiency increased and then decreased with increasing the concentrations of potassium permanganate, sulfuric acid, and the monomer, as well as polymerization temperature. The grafting reaction was characterized by an initial fast rate followed a lower rate which leveled off after a certain time. The overall activation energy for the grafting was estimated to be 66.9 kJ/mol.     

Synthesis and characterization of graft copolymers of Sago starch and acrylic acid

Sago starch has been graft copolymerized with acrylic acid (AAc) by mutual gamma radiation method. Reaction conditions such as total dose, monomer concentration and amount of methanol were optimized to obtain maximum grafting percentage. Maximum percentage of grafting, Pg (158.00%) was obtained at an optimum total dose of 62.64 kGy using 4.37 moles/L of AAc in 1 mL of methanol. Using optimum conditions, the effect of cross‐linker, glyoxal, on percent grafting was also studied and maximum grafting was obtained at [Glyoxal] = 54.70 moles/L. Characterization of the graft copolymer was carried out by FTIR, TGA, SEM, XRD analytical methods. The grafted Sago starch was found to have increased crystalline and improved thermal behavior. Swelling and solubility kinetics were measured for each of the samples and correlation between the effects of the reaction parameter on swelling‐solubility kinetics was evaluated. Maximum swelling (4192.3%) at 37°C in 8 h was observed for the sample with 59.9% graft level. Higher swelling percentage is indicative of the graft copolymer to have the properties of a hydro gels that can be utilized for use as drug delivery vehicle and purification of industrial effluents.     

Graft Copolymerization Onto Starch. 3: Grafting of Acrylamide Using Ceric Ion Initiation and Preparation of Its Hydrogels

The grafting of acrylamide (AM) onto maize starch in aqueous medium initiated by ceric ammonium nitrate (CAN) has been studied gravimetrically under nitrogen atmosphere. The effect of concentration of monomer and initiator, polymerization time and reaction temperature has been studied in terms of efficiency of grafting (%GE) and percentage Add-on (%Add-on). The %GE was found to decrease with increase in monomer concentration, but the reverse trend was obtained on increasing the polymerization time and temperature. The maximum %GE was obtained at 45°C when polymerization was carried out for 180 min using [CAN] = 0.004 mol/L and [AM] = 0.141 mol/L in 100 mL of distilled water with 2 g of starch. These graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. The graft copolymers showed enhanced thermal stability than pure starch. Hydrogels were prepared by grafting AM onto gelatinized maize starch followed by saponification of these graft copolymers with NaOH. The maximum water absorption obtained was 170 g/g.     

Modification of Carbohydrate Polymers via Grafting in Air. 2. Ceric‐Initiated Graft Copolymerization of Acrylonitrile onto Natural and Modified Polysaccharides

Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric‐carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N₂ atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi‐empirical expressions and time‐temperature profiles. An anomalous role of oxygen was observed, i.e., oxygen may act simultaneously as an inhibitor, comonomer and indirect initiator, depending on the type of polysaccharide. Measured grafting parameters, in most cases, showed a higher grafting yield and efficiency when the polymerization had been run under N₂. However, medium to high grafting percentages were also achieved in air.     

丙烯酰胺与聚乙烯醇的固相接枝共聚

为减少或避免溶液聚合溶剂后处理,研究了在固相条件下采用过硫酸铵 ∕ 亚硫酸氢钠的水溶性氧化还原体系作为引发剂,丙烯酰胺（AM）单体在聚乙烯醇（PVA）大分子链上的接枝共聚反应。利用FT-IR 红外光谱对其分子结构、表面官能团进行分析,通过X 射线衍射对接枝前后聚合物结晶度进行研究,运用差示扫描量热法测试其热力学性能,计算接枝参数,并对反应条件,如温度、时间、单体的加入量、引发剂的加入量等对接枝参数的影响进行了讨论。得到接枝率达61%的接枝共聚产物的反应条件：PVA 为50g;AM 为35g;接枝反应前在40 ℃下用少量水溶胀120min;接枝反应温度为40 ℃;引发剂（NH₄）_２Ｓ_２O_８和NaHSO ₃ 的加入量分别为0.02g 和1.01g。     

乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物比较

分别采用乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物,对其接枝参数进行比较,并利用红外光谱、扫描电子显微镜等测试手段对接枝共聚物微观结构进行分析比较,确定乳液聚合法和微波法制备淀粉与苯乙烯接枝共聚物为同一物质;通过比较得出乳液聚合法接枝百分率和接枝效率高于微波法,而微波法节约时间和能源。     

胶原水解物的接枝改性及其乳液特点研究

以甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)复合单体在过硫酸铵(APS)的引发下,改性皮胶原水解物,合成了接枝改性后的蛋白乳液。考察了引发剂(APS)浓度,蛋白与单体的质量比和丙烯酸酯单体配比对产物的接枝率(G%),接枝效率(E%),乳液平均粒度和Zeta电位的影响,测定了乳液黏度、稀释稳定性和pH值等参数。确定了乳液在各反应条件下的特点,有利于后期的交联固化处理,制备胶粘剂;用傅里叶红外光谱仪证明了丙烯酸酯成功接枝到了蛋白骨架上;TGA分析表明,纯的接枝产物具有明显的抗水性。     

降解淀粉与乙烯基单体AA-AN-AM接枝共聚物复鞣剂的合成及应用研究

氧化降解的玉米淀粉与丙烯酸(AA)、丙烯腈(AN)和丙烯酰胺(AM)在引发剂(NH4)2S2O8作用下进行了接枝共聚合反应，制得改性淀粉复鞣剂。研究了单体浓度及配比、引发剂浓度等因素对接枝共聚合反应的接枝率、单体转化率、接枝效率等的影响，用红外光谱对接枝共聚物的结构进行了分析表征，同时进行了应用实验。     

三硅氧烷型吡啶类离子液体表面活性剂的合成与表征

通过两步法制备了一种三硅氧烷型吡啶类离子液体表面活性剂([Si(3)Py]Cl),用IR、1H NMR和13C NMR对产物的结构进行表征,表面活性和聚集行为通过表面张力仪、动态光散射(DLS)和负染色透射电镜(TEM)进行测量.结果表明:[Si(3)Py]Cl具有良好的表面活性,其cmc为24.81 mmol/L,γcmc为23.04 mN/m,在水溶液中能聚集成直径为50~100 nm的囊泡.     

Microwave‐accelerated Synthesis and Characterization of Potato Starch‐g‐poly(acrylamide)

Using a very low concentration of potassium persulfate as initiator, acrylamide could be efficiently grafted onto potato starch under microwave irradiation and for the grafting O₂ removal from the reaction vessel was not required. Under optimal conditions, grafting and efficiency observed were 160% and 89%, respectively. Grafted starch was characterized by using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA). It was observed that the microwave irradiation could significantly accelerate the synthesis of starch‐graft‐poly(acrylamide), because under identical conditions no grafting was observed in a conventional procedure. Viscosity, shear stability and water/saline solution retention of the microwave‐synthesized grafted starch were studied and compared with that of the parent starch.     

离子液体-球磨法制备柠檬籽纤维素纳米纤丝及其结构表征

为推进柠檬加工副产物的高值化利用和开发纳米纤维素高效制备方法,本研究以柠檬籽为原料,采用不同质量分数（0～50%）的离子液体1-丁基-3-甲基咪唑氯化物（1-butyl-3-methylimidazolium chloride,[BMIM]Cl）为湿磨介质,通过机械球磨法制备柠檬籽纤维素纳米纤丝（lemon seed cellulose nanofibrils,LSCNF）,并以原子力显微镜、傅里叶变换红外光谱（Fourier transform infrared spectrometer,FTIR）、X射线衍射（X-ray diffraction,XRD）和热重分析对LSCNF的形貌和结构进行表征。结果表明,随着[BMIM]Cl质量分数的增加,获得的LSCNF粒径逐渐缩短,直径逐渐增长;当[BMIM]Cl质量分数为50%时,LSCNF的粒径最短,但直径相对较大（40～60 nm）。XRD和FTIR分析结果显示所有样品均为纤维素Iβ晶型,且添加[BMIM]Cl使LSCNF的结晶区域不易被破坏。热重分析结果显示离子液体-球磨法制备的LSCNF在500 ℃时残余质量分数和柠檬籽纤维素相近,但都高于仅用球磨方式制备的LSCNF。流变学分析结果表明LSCNF悬浮液均表现为非牛顿流体,且剪切速率一定时,粒径更长的LSCNF黏度更高。综上,将离子液体和球磨结合的绿色方法能从柠檬籽中高效制备LSCNF,且能根据离子液体的质量分数对LSCNF的形态和结构进行调控。     

卤胺类单体接枝棉织物的抗菌整理工艺

 以过硫酸钠为引发剂,研究了甲基丙烯酰胺在棉织物上的接枝共聚反应及其抗菌效果。实验分别测定轧烘焙工艺(DPC)和浸渍工艺对棉织物含氯量的影响。轧烘焙工艺最佳工艺条件：引发剂和单位浓度分别为30g/L和90g/L;轧余率76%;反应时间3min;焙烘温度和时间分别是150℃和1.5min。最佳工艺含氯量为0.52%。浸渍工艺引发剂和单体浓度分别为30g/L和50g/L,反应时间为180min,含氯量可达1.11%。利用红外、SEM等对接枝织物的结构与性能进行了表征,结果表明自由基引发下,棉织物可有效地接枝共聚甲基丙烯酰胺。抗菌结果表明含氯量为0.52%的改性棉织物抗菌效果明显。     

蚕丝的接枝共聚反应动力学及其接枝结构

在真丝与DMAAm（N,N’-二甲基丙烯酰胺）的接枝共聚合反应中,分别加入两种RAFT（可逆加成-断裂-转移）试剂,RAFT试剂与源自引发剂分解的自由基进行链转移反应,生成新的齐聚物自由基。研究发现,RAFT-ST3试剂断裂生成的PAA-PST*（聚丙烯酸-聚苯乙烯）自由基提高了接枝共聚合反应速率,真丝接枝率和单体接枝效率;RAFT-AA30试剂断裂生成的PST-PAA*自由基对接枝共聚合反应动力学无影响。FT-IR（傅里叶红外光谱）分析表明,RAFT试剂及其衍生物并未与真丝共价键链接,接枝率仍由PDMAAm接枝链贡献。SEM（扫描电镜）显示,与常规接枝真丝相比,RAFT反应提高了纤维表面接枝聚合物分布的均匀性。     

魔芋葡甘聚糖接枝共聚物／聚乙烯醇共混表面施胶剂的制备及性能

选用丙烯酸和丙烯酸丁酯为单体对魔芋葡甘露聚糖（KGM）进行自由基接枝共聚改性,将得到的聚合物乳液与聚乙烯醇共混,共混后乳液作为纸张表面施胶剂,研究其对纸张性能的影响。结果表明：改性后KGM粒子被共聚物包裹形成核一壳结构,复合乳胶粒子的粒径在40～50nm之间,KGM亲水性下降,结晶性也得到了一定的提高。KGM接枝共聚物乳液／聚乙烯醇共混乳液对纸张进行表面施胶处理后,纸张的施胶度、耐折度和抗张指数也得到了明显的提高。     

反相乳液聚合制备阳离子改性接枝淀粉

本实验以淀粉、丙烯酰胺、阳离子单体(二甲基二烯丙基氯化铵)为原料,采用过硫酸铵-尿素氧化还原引发体系,以油酸失水山梨醇酯为乳化剂,通过反相乳液聚合技术,合成阳离子改性淀粉接枝共聚物.分析讨论了单体配比、乳化剂用量、引发剂用量及油水体积比等合成条件对共聚物性能的影响,并采用正交实验方法对合成条件进行了优化.     

马来酸酐酯化预处理型PAA接枝淀粉浆料

通过对淀粉进行马来酸酐酯化预处理,在淀粉大分子上引入碳碳双键,再将这种含有碳碳双键的淀粉与丙烯酸单体进行接枝共聚合反应,以期大幅度提高淀粉与丙烯酸单体接枝共聚合反应的接枝效率,进一步提高接枝变性淀粉浆料的上浆性能。研究结果表明,当淀粉酯化取代度在0.0136~0.0412范围内,这种酯化预处理能使淀粉对丙烯酸的接枝效率提高10%~30%,并能显著改善接枝淀粉浆料对纤维的黏附性能以及浆膜性能。实验证实这种淀粉酯化预处理的酯化变性程度以取代度等于0.0136~0.0206为宜。     

衣康酸/丙烯酸与聚酯织物接枝共聚性能

研究了在水溶液中以过氧化苯甲酰为引发剂,衣康酸/丙烯酸为单体与碱处理后的三叶形聚酯(PET)平纹织物接枝共聚;对共聚条件如聚合温度、时间、引发剂浓度、单体物质的量比等进行研究,得出最佳聚合条件。电子扫描电镜照片和傅里叶红外变换光谱显示衣康酸/丙烯酸共聚到聚酯大分子上。研究结果表明随着接枝率的上升,织物吸湿快干性能提高;阳离子染料上染率大幅度提高,织物色光鲜艳。     

新型离子液体亲和萃取鸡蛋清中的溶菌酶

建立并优化利用辛巴蓝(Cibacron Blue F-3GA,CB)修饰[C₄MIM]Cl的新型离子液体[C₄MIM]₃CB特异性萃取分离鸡蛋清中溶菌酶的方法,并采用AutoDock Vina分析[C₄MIM]₃CB与蛋白的结合能,研究溶菌酶与[C₄MIM]₃CB相结合的能力。通过亲和萃取和反萃取并进一步脱盐、浓缩、冷冻干燥,得到溶菌酶产品。结果表明,通过对影响因素的研究,优化出最佳的萃取分离条件:蛋清粉溶液pH为7,新型离子液体中[C₄MIM]₃[CB]浓度为8 mg/mL,反应震荡时间为15 min,反萃取KCl溶液pH为7.0,浓度为1.5 mol/L。最终250 mg蛋清粉可得12.3 mg的溶菌酶产品,纯度为97.56%,酶活力为35000 U/mg,纯化倍数达到37.39,酶活回收率89.74%,且与其他蛋白达到完全分离。该方法具有选择性高、操作简便、产物纯度和活性高等优点。