反相悬浮-化学交联法制备聚乙烯醇交联微球CPVA

以聚乙烯醇(PVA)为单体,戊二醛(GA)为交联剂,山梨醇酐单硬脂酸酯(span60)为分散剂,采用反相悬浮一化学交联法,制备了聚乙烯醇交联微球CPVA,采用FT-IR和SEM对其化学结构和微观形貌进行了表征,考察了搅拌速率、交联剂的用量、催化剂(盐酸)的用量对交联微球的成球性能及粒度的影响规律.结果表明,在反相悬浮体系中,搅拌速度、交联剂的用量是影响交联微球制备的主要因素,当搅拌速度小于250r/min、交联剂的用量大于2ml时,体系中均不能成球.在体系中加入盐酸后,交联微球的粒径随盐酸用量的增大而增大.控制成球的反应条件可以制备出球形度良好、粒径在150μm左右的粒径可控的聚乙烯醇交联微球CPVA.     

反相悬浮—化学交联法制备聚乙烯醇交联微球CPVA

以聚乙烯醇（PVA）为单体,戊二醛（GA）为交联剂,山梨醇酐单硬脂酸酯（span-60）为分散剂,采用反相悬浮-化学交联法,制备了聚乙烯醇交联微球CPVA。采用FT-IR和SEM对其化学结构和微观形貌进行了表征,考察了搅拌速率、交联剂的用量、催化剂（盐酸）的用量对交联微球的成球性能及粒度的影响规律。结果表明,在反相悬浮体系中,搅拌速度、交联剂的用量是影响交联微球制备的主要因素,当搅拌速度小于250r/min、交联剂的用量大于2mL时,体系中均不能成球。在体系中加入盐酸后,交联微球的粒径随盐酸用量的增大而增大,控制成球的反应条件可以制备出球形度良好、粒径在150μm左右的粒径可控的聚乙烯醇交联微球CPVA。     

聚丙烯酸–丙烯酰胺交联微球的制备及吸水性能

以丙烯酸(AA)、丙烯酰胺(AM)作为单体,N,N–亚甲基丙烯酰胺(MBA)作为交联剂,利用反向悬浮聚合法制备聚丙烯酸–丙烯酰胺(PAA–AM)交联微球,研究了单体配比、交联剂用量、分散剂浓度、搅拌速度、AA中和度对交联微球吸水性能的影响。结果表明,当单体中AM的质量分数为60%、交联剂用量为1%、AA中和度为80%、分散剂浓度为1%、搅拌速度为350 r/min,交联微球的吸水倍率分别达到最大值450.77,426.83,426.83,426.83,424.23 g/g。     

PAA-AM交联微球聚合工艺及微球粒径的研究

以丙烯酸(AA)、丙烯酰胺(AM)作为单体、N,N-亚甲基丙烯酰胺(MBA)作为交联剂,利用反向悬浮聚合法制备聚丙烯酸-丙烯酰胺交联微球,研究了分散剂的HLB值及用量、丙烯酸中和度、搅拌速度和交联剂用量对聚合反应及微球粒径的影响。结果表明,分散剂的HLB值为4.5、丙烯酸中和度为80%、搅拌速度为350 r/min、交联剂用量为1%~1.5%的时候,聚合反应过程平稳,所得微球粒径大小适中且分布均匀。     

反相悬浮聚合法制备阳离子性CPDAC凝胶微球及其对水污染化合物的吸附性能

以环已烷为分散介质、Span-60为分散剂,采用反相悬浮聚合法,通过阳离子单体丙烯酰氧乙基三甲基氯化铵(DAC)的交联聚合(CP),制备了粒径200~300 mm的凝胶微球CPDAC,考察了主要条件对微球成球性能及粒径的影响,对微球进行了表征,研究了CPDAC对4种阴离子物质的吸附特性. 结果表明,制备CPDAC需严格控制成球条件. 分散相水相采用滴加方式,适宜的分散剂为Span-60,随其用量增加微球粒径变小;油水相体积比小于2:1不能成球,随体积比增大,微球粒径减小;搅拌速率小于250 r/min不能成球,微球粒径随搅拌速率加快而变小. CPDAC凭借强离子交换作用及静电相互作用对CrO42-, MoO42-和酸性染料活性艳红、活性黄4种阴离子物质都有很强的吸附作用,吸附容量分别为213, 275, 1850和1690 mg/g,吸附容量随温度升高而降低.     

高交联度聚苯乙烯微球聚合工艺的研究

以二乙烯基苯(DVB)为交联剂,通过悬浮聚合合成了主要粒径范围为0.425～0.850 mm的高交联度聚苯乙烯(PS)微球。考察了反应温度、反应时间、搅拌速率、分散剂种类及用量和水油质量比对微球粒径的影响,确定了最佳聚合工艺:采用分段升温且增加低温段反应时间,搅拌速率为110～130 r/min,主分散剂聚乙烯醇(PVA)质量分数为0.076%,助分散剂磷酸三钙(TCP)质量分数为0.053%,水油质量比为(2～2.6)∶1。     

悬浮聚合制备微米级聚苯乙烯微球

以羟乙基纤维素和白明胶为稳定剂、甲苯和庚烷为致孔剂,经悬浮聚合制备了单分散交联聚苯乙烯微球。考察了单体用量、引发剂和交联剂含量、搅拌速度对微球粒径的影响。结果表明,最佳的悬浮聚合条件为：单体苯乙烯的用量为水相的质量分数20%、交联剂二乙烯基苯为单体的质量分数4%、引发剂过氧化苯甲酰为单体的质量分数1%、聚合温度为60 ℃、搅拌速度为500 r/min、反应时间为24 h。在此条件下制备的交联聚苯乙烯微球平均直径为40 μm左右,扫描电镜观察结果显示,合成的交联聚苯乙烯微球的形态良好且表面有微孔,分散性好。     

Ce(Ⅳ)盐引发丙烯腈在交联聚乙烯醇微球表面的接枝聚合

以戊二醛为交联剂,在反相悬浮体系中采用直接交联反应成球的方法,制备了聚乙烯醇(PVA)。以硫酸铈铵为引发剂,在酸性溶液聚合体系中实施了丙烯腈(AN)在交联微球CPVA表面的接枝聚合,制备了接枝微粒CPVA-g-PAN,考察了主要因素对交联成球反应与接枝聚合的影响规律。实验结果表明,在一定的搅拌速度下,分散剂用量及油水两相比是影响交联微球CPVA的主要因素。在Ce(Ⅳ)盐的氧化作用下,在含有大量羟基的CPVA微球表面会产生自由基,顺利地实现丙烯腈的自由基接枝聚合反应。反应温度、铈盐浓度和H+离子浓度是影响接枝聚合反应的主要因素。在适宜条件下,可制得PAN接枝度为27 g/100 g的接枝微球CPVA-g-PAN。     

悬浮共聚粒径大小及分布的研究

本文以丙烯酸酯系列为原料，采用悬浮聚合的方法形成聚合物，研究引发剂的用量和种类，交联剂的用量，水油比，分散剂的用量和种类，搅拌速度，单体种类等因素对粒径大小及分布的影响。     

含羟基的松香基聚合物微球的制备、表征及吸附性能

以苯乙烯(St)为单体,丙烯酸松香与甲基丙烯酸缩水甘油酯(GMA)的酯化物(RAG)为交联剂,明胶为分散剂,偶氮二异丁腈(AIBN)为引发剂,采用悬浮聚合法制备了含羟基的松香基聚合物微球。探讨了分散剂用量、单体配比及搅拌速度对微球性能的影响。利用红外光谱、热重分析、光学显微镜和扫描电镜等对聚合物微球进行测试表征。结果表明:成功制备了含羟基的松香基聚合物微球,微球的热稳定性、球形和分散性较好。在m_(RAG)∶m_(St)=1∶1,引发剂AIBN用量为混合单体的1%,分散剂明胶用量为混合单体的6%,搅拌速度为500r/min,85℃下反应3h,升温至90℃熟化2h时,可以制备外观最佳的微球。当固液比为0.6g/L,pH=4.5,298K吸附4h时,该微球对苯甲酸的吸附量达到172.3mg/g。     

分散剂聚甲基丙烯酸钠的合成

探讨了甲基丙烯酸、甲基丙烯酸甲酯制备乳胶涂料及液相悬浮法生产氯化聚乙烯用分散剂聚甲基丙烯酸钠的合成方法，叙述了各种因素对工艺的影响。     

Damping Properties of Polyorganosiloxane/Poly(methyl methacrylate) Interpenetrating Networks

Interpenetrating polymer networks (IPNs) based on polyorganosiloxane/poly(methyl methacrylate) were prepared via sequential polymerization and the damping and mechanical properties of these materials were studied. The effects of crosslinking in both the first‐ and second‐formed networks were investigated. The experimental results show that the extent of damping of the IPNs was decreased and shifted to higher temperature as the content of poly(methyl methacrylate) was increased; the mechanical properties such as tensile strength and hardness (Shore A) were increased with increasing poly(methyl methacrylate) (PMMA) content. The loss factor peak becomes narrower with increasing crosslinker level in the first‐formed network (polysiloxane network), while increasing crosslinker content in the second‐formed network (PMMA network) results in a broadening of the IPN transition peak and moves the IPN transition to higher temperatures as well.     

Dielectric analyses of a series of poly(2-hydroxyethyl methacrylate-co-2,3-dihydroxypropyl methacylate) copolymers

The dielectric spectra of a series of copolymers of 2-hydroxyethyl methacrylate (HEMA) and 2,3-dihydroxypropyl methacrylate (DHPMA) were investigated. Recently, the full range dielectric spectrum of poly(2-hydroxyethyl methacrylate) was reported. This study looks at the effects on the dielectric behavior as a result of 2,3-dihydroxypropyl methacrylate addition. The dielectric permittivity, ε′, and the loss factor, ε″, were measured using a dielectric analyzer in the frequency range of 0.6 Hz to 100 kHz and between the temperature range of −150 and 275 °C. The electric modulus formalism was used to reveal the viscoelastic and conductivity relaxations present in the polymers. Several notable changes were observed as 2,3-dihydroxypropyl methacrylate concentration increased. It was observed through DSC and DEA that the glass transition temperature decreased as DHPMA content increased. The secondary dielectric relaxations were also affected as it was recorded that the activation energy for the γ transition increased and the β relaxation decreased with DHPMA content. Ionic conductivity data prove that DHPMA facilitates ionic mobility more efficiently than HEMA.     

甲基丙烯酸丁酯-PEG梳形共聚物的合成与表征

以偶氮双异丁腈(AIBN)为引发剂,四氢呋喃为溶剂,采用甲基丙烯酸正丁酯(BMA)与聚乙二醇单甲醚甲基丙烯酸酯(POEM)共聚制备了支链上含聚乙二醇(PEG)的梳形共聚物。采用1H-NMR、DSC和表面接触角等方法研究了梳形共聚物的结构与性能。结果表明,聚合物中两结构单元的含量与单体投料比中的含量基本一致;投料比对聚合物的结构和性能有较为显著的影响;梳形聚合物的熔点、焓值及静态接触角随着共聚物中BMA含量的升高而升高。     

Preparation and Characterization of Poly(Methyl Methacrylate) Microbeads by Dispersion Polymerization: Effects of the Medium Composition,Monomer Concentration,Thermal, and Optical Properties

This study investigated the relationship between particle size, particle distribution, thermal, and optical properties of poly(methyl methacrylate) microbeads using dispersion polymerization under various methanol/water (MeOH/H₂O) dispersion medium ratios and methyl methacrylate acid concentrations. The particle size of the poly(methyl methacrylate) microbeads increased when the medium solubility and monomer concentration increased simultaneously. In addition, the molecular weight and polydispersity of the poly(methyl methacrylate) microbeads were increased as the methanol ratio increased. The refractive index increased as the content of the poly(methyl methacrylate) microbeads increased with wavelengths of 546 and 589 nm.     

甲基丙烯酸-2-羟丙酯与甲基丙烯酸乙酯的共聚

介绍了以过氧化苯甲酰为引发剂 ,甲基丙烯酸 - 2 -羟丙酯与甲基丙烯酸乙酯进行的共聚合反应。通过测得共聚物中羟基的含量确定了共聚物的组成 ,且以线性化方法求出共聚反应中两种单体的竞聚率 ,所得结果为γHPMA=1 80 ,γEMA=0 2 4     

Stereoregular poly(alkyl methacrylate)s: polymer-polymer and copolymer-polymer blends

Amorphous blends of isotactic and syndiotactic poly(methyl methacrylate) were found to be compatible. To evaluate the interaction between these tactic polymers, random copolymers of isotactic poly(methyl/ethyl methacrylate) were blended with syndiotactic poly(methyl methacrylate). Only the copolymers with an ethyl methacrylate content below 45% were compatible with syndiotactic poly(methyl methacrylate). Using a Flory-Huggins type treatment of copolymer mixtures, the segmental interaction parameters for poly(methyl methacrylate) with poly(ethyl methacrylate) and for isotactic with syndiotactic poly(methyl methacrylate) were calculated. The interaction parameter for the tactic poly(methyl methacrylate) pair was found to be small and negative.     

Differential microemulsion polymerization as a new root for entrapment of drugs

Nanosized particles derived from poly(methyl methacrylate) as well as copolymer of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) were synthesized by differential microemulsion technique in the presence of ammonium persulfate as water‐soluble initiator. The polymerization was stabilized by adding biologically safe emulsifiers namely the sodium dodecyl sulfate (SDS) or polyvinyl pyrrolidone (PVP) either alone or in conjunction with polyethylene glycol. The turbidity measurements, surface tension, ζ potential, and morphological characterizations of the obtained nanosized poly MMA and its copolymer with HEMA in different monomer feed compositions were investigated. It is found that increasing HEMA content leads to increase in the particle size, turbidity measurements but the negatively charged ζ potential decreased. However, when SDS is used, the surface tension of the prepared lattices increased, whereas it is decreased by using PVP. Kinetic studies of (MMA/HEMA) in ratio of 95/5 wt % in the presence of SDS or PVP revealed that the emulsifier concentration has a considerable effect on the rate of polymerization and the power of the emulsifier. The entrapment of drug was investigated using two active molecules different in water solubility (sodium warfarin and ibuprofen). It is noted that entrapment efficiency is independent of HEMA content in the monomer feed composition but dependent on type of drug and the amount of drug introduced. Hence, higher entrapment efficiency was attained for sodium warfarin (more hydrophilic) than that of ibuprofen (more hydrophobic) and they were 95.5 and 85%, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Comparing emulsion polymerization of methacrylate-monomers with different hydrophilicity

A comprehensive experimental study concerning the influence of various types of initiator-emulsifier systems on emulsion polymerization of methacrylate monomers (2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and butyl methacrylate (BMA)) reveals interesting relations between initiator and surfactant hydrophilicity on the one hand and the hydrophilicity of the monomers on the other hand. For the water-soluble HEMA stable latexes are only obtained if hydrophobic initiators such as 2,2′-azobisisobutyronitrile or dibenzoyl peroxide in combination with alkyl sulfate surfactants with carbon chain lengths greater than 10 or surface active initiators of the 2,2′-azobis(N-2′-methylpropanoyl-2-amino-alkyl-1)-sulfonate type with alkyl chain lengths greater than 8 are employed. Stable nano size range poly(2-hydroxyethyl methacrylate) (PHEMA) particles have been prepared also by batch emulsion polymerization using ionic surface active initiators (inisurfs). The results clearly show that the formation of stable latex particles requires a proper choice of the initiator-emulsifier system regarding its hydrophilic-hydrophobic balance. The PHEMA particles prepared with surface-active initiators keep their identity and spherical shape even in the dried state whereas in the case of the other initiator-emulsifier systems complete coagulation and coalescence occurs during drying.