Formation of macroporous styrene–divinylbenzene copolymer networks: Theory vs. experiments

A kinetic–thermodynamic model is presented to predict the total porosities of macroporous copolymer networks formed by free‐radical crosslinking copolymerization of styrene (S) and commercial divinylbenzene (DVB, a mixture of meta and para DVB isomers and ethylstyrene). The kinetic part of the model predicts, based upon the method of moments, the concentration of the reacting species, the gel, and sol properties as a function of the monomer conversion. The thermodynamic part of the model describes the phase equilibria between the gel and separated phases during the S–DVB copolymerization and predicts the volume of the separated phase, which is the pore volume of the crosslinked material, as a function of the monomer conversion. Calculation results show that the porosity of S–DVB networks increases as the polymer–diluent interaction parameter increases, or as the initial monomer concentration decreases. Porosity also increases on increasing the DVB content of the monomer mixture. Both the polymerization temperature and the initiator concentration affect significantly the kinetics of S–DVB copolymerization. However, the final porosity of S–DVB copolymers is largely insensitive to the amount of the initiator and to the polymerization temperature. All calculation results are in accord with the experimental data published previously. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2181–2195, 1999     

Chromatographic properties of macroporous beads from poly(GMA-co-EDMA)

A series of macroporous glycidyl methacrylate-ethylene dimethacrylate copolymers have been prepared by the suspension polymerization according to a statistical design of experimental approach in which concentration of ethylene dimethacrylate and time needed for raising the polymerization temperature from 20 to 70°C have been varied. The porous properties of hydrolyzed copolymers have been characterized by means of size exclusion chromatography using polystyrene standards in tetrahydrofuran. Pore volume, specific surface area, and pore size are affected by the crosslinking agent concentration rather than by the rate of temperature increase during the polymerization reaction.     

Reactive polymers. XXXII. Effect of composition of polymerization feed on morphology and some physical properties of macroporous suspension copolymers glycidyl methacrylate–ethylene dimethacrylate

The effects of inert solvent concentration of crosslinking agent and initiator and polymerization temperature on specific surface area, porosity, penetration modulus, stress at break, and inner and surface morphology of the copolymer glycidyl methacrylate–ethylene dimethacrylate were investigated. There is a direct influence of interfacial tension between the continuous and dispersed phases in suspension at the beginning of polymerization on the morphology of the bead, and hence on the resulting physical characteristics of the structure.     

Development of porous polymer monolith by photoinitiated polymerization

Porous polymer monoliths have been successfully prepared by photoinitiated polymerization of butyl methacrylate (BMA) and ethylene glycol dimethacrylate (EDMA) monomers in porogenic solvent of methanol. Mercury intrusion porosimetry and scanning electron microscope are used to characterize the porous properties; nevertheless, the pore size obtained from both techniques is not comparable. The porous structure of the porous polymers is controlled by the phase separation during the polymerization and crosslinking. By varying the composition of the starting solution such as initiator fraction, BMA/EDMA ratio, porogen fraction, and UV intensity, porous polymers with median pore size from about 140 nm to 3 μm can be obtained, and the pore size distribution for majority of the porous polymers is also narrow. The results present a very positive prospect to microfluidic applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高固含量聚丙烯酰胺反相微乳液的制备

研究了高单体质量分数(25%～40%)下丙烯酰胺的反相微乳液聚合反应,使用工业白油作为分散介质,使用复合非离子乳化剂稳定反应体系,使用焦亚硫酸钠引发聚合。研究了引发剂组成及浓度、交联剂浓度、温度及单体浓度对反应转化率和聚合物分子质量的影响。结果表明,转化率和分子质量主要受引发剂浓度及单体浓度的影响。根据筛选出来的优化条件,制备了固含量接近40%、分子质量约850万的聚丙烯酰胺微乳液。     

Effect of porogenic solvent on the porous properties of polymer monoliths

Polymer monoliths with open pores and median pore size of about 15 nm–3 μm have been successfully synthesized by photoinitiated polymerization of butyl methacrylate and ethylene glycol dimethacrylate monomers. The solubility of the monomers in a porogenic solvent is determined by Hildebrand solubility parameter, and it is found that it has great effect on the pore size of the polymers synthesized. Polymers with larger pores are usually generated with poorer solvents for the monomers. However, polymers with different pore sizes and porosities have been obtained using porogenic solvents with similar Hildebrand solubility parameters. The evaporation rate of the porogenic solvents might be another critical factor affecting the properties of the polymer monoliths. Moreover, the effect of water as a cosolvent on the pore size and porosity of the polymers have also been investigated. Polymers with larger pore size have been prepared with the presence of water due to the occurrence of earlier phase separation in the polymerization. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of reactive macroporous poly(glycidyl methacrylate‐triallyl isocyanurate‐ethylene glycol dimethacrylate) microspheres by suspension polymerization: Effect of synthesis variables on surface area and porosity

A novel macroporous poly(glycidyl methacrylate‐triallyl isocyanurate‐ethyleneglycol dimethacrylate) copolymer, hereinafter P_{GMA‐TAIC‐EGDMA}, of controlled bead size was prepared via free radical suspension copolymerization. The effects of varying the concentration of crosslinking agents and porogenic diluent on the average pore diameter, pore size distributions, specific surface area, and pore volume of the copolymer matrix were thoroughly investigated. The spherical beads were characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The specific pore volume, average pore diameter, pore size distribution, and the specific surface area were measured by Mercury intrusion porosimetry and BET adsorption method, respectively. The porous properties of the polymer matrix are a direct consequence of the amount and quality of the porogenic solvent, the percentage of crosslinking monomers, and the ratio between the monomers and porogen phases. When the polymer was prepared at 30 and 40% crosslinking density, and 75 and 100% diluents, respectively, it showed a fine beads morphology, mechanical stability and pore size distributions. By comparing the copolymers P_{GMA‐TAIC‐EGDMA} and P_GMA‐EGDMA, it was found that the former is more stable both thermally and mechanically than its predecessor. The presence of epoxide functionalities of macroporous P_{GMA‐TAIC‐EGDMA} beads makes it a versatile carrier. The resulting polymers have the potential for wide applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Poly(2-hydroxyethyl acrylate-co-ethyleneglycol dimethacrylate) monoliths synthesized by radiation polymerization in a mold

Copolymer monoliths of diethyleneglycol dimethacrylate and 2-hydroxyethyl-acrylate were prepared by using the advantage of radiation initiated polymerization over the thermally initiated polymerization, namely, that it is sufficient to use only a monomer and a porogenic solvent and no initiator is needed. Besides, the reaction can take place at any desired temperature in a mold of suitable size and shape.The results showed that increase of the HEA content in the comonomer mixture (up to 18 vol%) resulted in monoliths with increased pore size and hydrophilic character. The specific surface area of these monoliths was in the order of 1 m²/g. The porous properties could be fine-tuned by changing the solvent.Flow rate measurements for several eluents indicated that these monoliths could be useful as chromatographic columns. This is illustrated by separation of several amino acids.     

一种复合二氧化钛大孔共聚物的合成及其在扩张床吸附中的应用(Ⅰ)基质合成及其特性

以甲基丙烯酸缩水甘油酯和双甲基丙烯酸乙二醇酯作单体 ,在致孔剂存在下通过悬浮聚合将经过表面改性处理的二氧化钛超细颗粒包埋其中 ,制得一种密度增大的复合二氧化钛大孔共聚物 (GET) ,作为扩张床吸附基质 .研究了二氧化钛添加量、交联剂用量、致孔剂用量和配比对共聚物湿真密度和孔结构的影响     

一种复合二氧化钛大孔共聚物的合成及其在扩张床吸附中的应用（Ⅰ）基质合成及其特性

以甲基丙烯酸缩水甘油酯和双甲基丙烯酸乙二醇酯作单体，在致孔剂存在下通过悬浮聚合将经过表面改性处理的二氧化钛超细颗粒包埋其中，制得一种密度增大的复合二氧化钛大孔共聚物（GET），作为扩张床吸附基质.研究了二氧化钛添加量、交联剂用量、致孔剂用量和配比对共聚物湿真密度和孔结构的影响.     

高吸水性树脂的制备及交联剂对树脂吸水性能的影响

用反相悬浮聚合和滴加单体的方法制备以聚乙二醇双丙烯酸酯交联的聚丙烯酸钠高吸水性树脂。详细探讨了温度，引发剂和单体浓度，油水比等最佳反应条件。     

Reactive polymers,XXIX. The effect of components on the rate of polymerization in model mixtures containing glycidylmethacrylate and ethylenedimethacrylate

The effect of the concentration of crosslinking agent, of the amount and composition of inert components and of the concentration of initiator on the process of radical copolymerization of glycidylmethacrylate with ethylenedimethacrylate modelling the situation arising in suspension polymerization has been studied. It was found, that the rate of polymerization decreases with increasing concentration of the crosslinking agent in the mixture, which also brings about extension of the time after which the reaction mixture becomes turbid. Causes underlying these phenomena are discussed.     

含物理交联高吸油树脂的合成和吸油性能

提出在单一化学交联吸油树脂中引入物理交联的设想，并采用悬浮聚合法全盛了含部分物理交联和单一化学交联的高吸油聚丙烯酸酯。研究了聚合温度、反应时间以及引发剂、分散剂用量和交联剂形式及用量对树脂形态、凝胶分率和吸三氯乙烯、苯等的影响。结果表明物理交联和化学交联方式对树脂的吸油性能影响较大。     

微波辐射法合成阴离子型聚丙烯酰胺

以丙烯酰胺（AM）和丙烯酸钠（AA-Na）为原料,过硫酸铵为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,用微波辐射进行水溶液聚合制备可溶解的阴离子型聚丙烯酰胺。探讨丙烯酸中和度、单体浓度、引发剂用量、交联剂用量及温度等对相对分子质量的影响。结果表明,单体浓度为19%,中和度为80%,引发剂用量为0.05%,交联剂用量为0.002%,反应温度35℃条件下合成的聚丙烯酰胺（PAM）的相对分子质量最高。     

Study of the synthesis and properties of PBA/PS/PMMA latex interpenetrating polymer networks

In this article, we use the technique of multistage emulsion polymerization to synthesize the LIPN PBA/PS/PMMA and use the gravimetric analysis method to study the apparent kinetics of the reaction process and to investigate the influence of the concentration of the initially emulsifying agent, the initiator, and the extent of the crosslinking on the distribution of the particle diameter and the dynamic mechanical properties of the products.     

亲水-疏水PVP-semi-IPN-PCL水凝胶的制备与溶胀性能

N-乙烯基吡咯烷酮（NVP）在聚己内酯（PCL）的乙酸乙酯溶液中进行自由基聚合,制备了亲水-疏水性聚乙烯吡咯烷酮（PVP）/聚己内酯（PCL）半互穿网络水凝胶（PVP-semi-IPN-PCL）。凝胶中PCL的熔融温度T_m无明显变化,而T_m吸热峰形状随PVP含量变化。凝胶平衡溶胀率（ESR）随PVP含量的升高而增大,结合水量的增大尤其显著。由于“笼蔽效应”,低浓度引发剂时,偶氮二异丁睛（AIBN）引发制备的凝胶ESR低于过氧化苯甲酰（BPO）引发剂。交联剂浓度较低时,以戊二醛交联形成凝胶的ESR较N,N-亚甲基双丙烯酰胺（NMBA）交联形成的凝胶大。浓度较高时,戊二醛交联凝胶ESR较NMBA低。PVP含量（质量）分别为20%、40%、60%、80%时,凝胶溶胀动力学Fick模型中的n值分别为0.854、0.471、0.466、0.253,说明在合适的PVP含量时,凝胶的溶胀动力学符合Fick模型。     

聚丙烯酸水凝胶的制备研究

以丙烯酸为单体,N,N＇-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,通过自由基聚合制备了聚丙烯酸水凝胶.考察了交联剂、引发剂、单体中和度、聚合温度以及盐溶液对水凝胶溶胀性能的影响.结果表明,引发剂为单体质量的0.6％,交联剂为0.8％,单体的中和度为70％时,凝胶的溶胀性能最佳,吸水率达到了3 000％以上,聚丙烯酸水凝胶的溶胀性能随着盐溶液浓度的增大而降低.     

正交法优化淀粉接枝共聚高吸水树脂的工艺条件

以过硫酸钾为引发剂,甘油溶液为交联剂,引发甘薯淀粉与丙烯酸接枝共聚反应。对影响反应的主要因素如丙烯酸中和度、引发剂的量、交联剂的量、体系用水量、淀粉糊化时间进行了研究。结果表明,淀粉接枝丙烯酸共聚高吸水树脂的最佳工艺条件为:丙烯酸中和度为70%,引发剂的量为60 mg,交联剂量为0.25 mL,体系用水量为40 mL,淀粉糊化时间为20 min。按此条件制得的树脂的吸水率为768 g/g     

自交联丙烯酸弹性乳液的合成研究及应用

利用双丙酮丙烯酰胺(DAAM)和己二酸二酰肼(ADH),合成了一种自交联丙烯酸弹性乳液,研究和分析了交联单体添加量、乳液玻璃化温度、乳化剂和引发剂及其加量对乳液及其弹性涂料性能的影响。研究表明,交联单体添加1.5%～2.0%,乳液玻璃化温度为-35～-25℃,乳化剂采用反应型和阴离子复配的乳化剂,其添加量为1.5%～2.0%,并使用过硫酸盐引发剂,其添加量为0.5%～1.0%,采用种子乳液聚合工艺,合成的乳液性能最好,制备的弹性涂料具有优异的力学性能和高耐沾污性。     

Fabrication of porous scaffolds with a controllable microstructure and mechanical properties by porogen fusion technique

Macroporous scaffolds with controllable pore structure and mechanical properties were fabricated by a porogen fusion technique. Biodegradable material poly (d, l-lactide) (PDLLA) was used as the scaffold matrix. The effects of porogen size, PDLLA concentration and hydroxyapatite (HA) content on the scaffold morphology, porosity and mechanical properties were investigated. High porosity (90% and above) and highly interconnected structures were easily obtained and the pore size could be adjusted by varying the porogen size. With the increasing porogen size and PDLLA concentration, the porosity of scaffolds decreases, while its mechanical properties increase. The introduction of HA greatly increases the impact on pore structure, mechanical properties and water absorption ability of scaffolds, while it has comparatively little influence on its porosity under low HA contents. These results show that by adjusting processing parameters, scaffolds could afford a controllable pore size, exhibit suitable pore structure and high porosity, as well as good mechanical properties, and may serve as an excellent substrate for bone tissue engineering.