超支化聚(胺-酯)-丙烯酸共聚物的合成

利用端单羟基超支化聚(胺-酯)与丙烯酰氯反应,制备了端基为双键的超支化聚(胺-酯)大分子单体(cHPAE),用该大分子单体与丙烯酸发生共聚合,合成了超支化聚(胺-酯)-聚丙烯酸共聚物(HPAE-co-AA),利用FTIR和1HNMR对大分子单体结构进行了表征,研究了反应条件对共聚产物分子量的影响.结果表明:共聚反应溶剂...     

接枝型水性聚合物分散剂的催化链转移聚合制备及其炭黑分散能力研究

应用催化链转移聚合技术合成末端带有可聚合双键的大分子单体,然后大分子单体进一步与主链单体共聚制备接枝聚合物,并通过定量酸性水解得到支链亲水、主链疏水的两亲接枝聚合物。同时系统研究了该聚合物的主链与侧链的分子量大小、主链锚定基团种类与浓度等因素对其在水性体系中炭黑分散能力的影响,为分散剂的结构优化奠定基础;所优选结构的分散剂其炭黑分散能力与进口分散剂Disperbyk-190相当。     

马来酸聚醚酯大分子单体的合成与表征

采用GPC、1H-NMR和双键滴定等方法,对马来酸聚醚酯大分子单体的结构进行了分析。结果表明,马来酸聚醚酯大分子单体的合成过程涉及复杂的化学变化,除发生酯化反应外,还涉及双键异构化、双键的加成等反应,双键加成反应增加了大分子单体的相对分子质量,降低了双键含量。反应温度对大分子单体双键保留率、顺反异构化程度和相对分子质量有着显著的影响,后者进而决定其在POP合成中的稳定效能。在120℃左右合成的大分子单体具有较好的稳定效能。     

双键单封端聚氨酯丙烯酸酯大分子单体的合成及表征

以异佛尔二酮异氰酸酯(IPDI)和聚醚二元醇(PEG)为单体、(甲基)丙烯酸羟乙酯和正丁醇为共封端剂,合成了以双键单封端为主的聚氨酯丙烯酸酯大分子单体.考察了反应条件的影响,对聚氨酯大分子单体进行了表征.结果表明反应温度越高、催化剂用皱越大、封端剂的羟基活性越强,预聚反应和封端反应所需时间越短;聚氨酯人分子单体中双键含量随IPDI与PEG摩尔比的增加而增加.     

沉淀聚合制备低分子量聚丙烯酸及残液循环利用

以偶氮二异丁腈(AIBN)为自由基引发剂,石油醚为溶剂,异丙醇为链转移剂,通过沉淀聚合制备了低相对分子质量(简称分子量,下同)的聚丙烯酸。考察了引发剂用量、链转移剂用量、单体质量浓度对聚合收率的影响,确定最佳聚合条件为:AIBN用量为单体质量的10%,链转移剂用量为单体质量的100%,单体质量浓度100g/L,反应温度80℃,反应时间4 h。反应结束后产品在底部沉淀析出,溶剂可循环利用,在最佳聚合条件下,残液循环利用5次,单体的累计转化率达到92.6%。凝胶渗透色谱(GPC)分析表明,通过残液循环制备的产品重均分子量(Mw)变化不大,保持在1 000～1 300,多分散性(PDI)为1.92～3.38。     

聚甲基丙烯酸甲酯大分子单体的合成及表征

甲基丙烯酸甲酯进行自由基溶液聚合 ,巯基乙醇为链转移剂 ,然后用丙烯酰氯封端制备了聚甲基丙烯酸甲酯大分子单体。研究了引发剂、反应时间、溶剂、反应温度对预聚体的产率的影响。对所合成的大分子单体进行了 IR、1H-NMR表征。适宜的反应条件为用 THF作溶剂 ,60℃反应 7～ 8h,预聚体可以达到80 %的产率。     

通过RAFT聚合合成星型聚合物

采用先臂法合成(tBA/HDDA)星型聚合物。由丙烯酸正丁酯(tBA)的可逆加成-断裂链转移自由基聚合(RAFT),得到线型PtBA大分子链转移剂;PtBA与双官能团的偶联剂1,6-己二醇二丙烯酸酯(HDDA)反应得到星型聚合物。研究了偶联剂HDDA与线型PtBA大分子链转移剂的摩尔比对合成星型聚合物的影响。采用GPC法测定了线型大分子链转移剂PtBA及星型聚合物的分子量和分子量分布。结果表明,HDDA与PtBA的比例越高,星型聚合物的产率越大;超过一定值,则产生凝胶。GPC结果表示,所得星型聚合物的分子量大,分子量分布窄(PD I<1.19)。     

双亲性嵌段共聚物的RAFT合成及其胶束化行为研究

以二硫化二异丙基黄原酸酯(DIP)为链转移剂,AIBN为引发剂,通过可逆加成-断裂链转移(RAFT)自由基聚合的方法制备得到大分子链转移剂聚醋酸乙烯酯(PVAc)。进而引发第二单体N-乙烯基乙酰胺(NVA)进行RAFT反应制备得到不同嵌段比的双亲性嵌段共聚物PVAc-bPNVA。红外光谱(FT-IR)、核磁共振氢谱(1 H NMR)和凝胶渗透色谱(GPC)分析表明,所得聚合物结构明确,且分子量分布较窄,符合活性聚合特征。进而使PVAc-b-PNVA在选择性溶剂(DMF/H2O)中自组装形成胶束,研究了不同初始浓度和链段比对胶束粒径和形态的影响。     

链转移剂单体存在下自由基NaSCN溶液聚合制备支化聚丙烯腈

以偶氮二异丁腈(AIBN)为引发剂,醋酸乙烯酯(VAc)为第二单体,甲基丙烯酸-3-巯基丙酰氧基乙酯(MMPOE)为链转移剂单体,45%硫氰酸钠(NaSCN)水溶液为溶剂,进行常规自由基共聚反应合成支化聚丙烯腈(BPAN);研究了链转移剂单体含量对聚合物的影响。通过气相色谱(GC)、核磁共振氢谱(1H-NMR)、三检测凝胶渗透色谱(TD-GPC)、旋转流变仪分别对聚合反应过程和聚合产物进行了表征分析。结果表明:在NaSCN水溶液体系中,以MMPOE为链转移剂单体制得了较高支化程度的支化PAN,其支化程度随MMPOE含量的增加而提高,分子量随MMPOE含量的增加而降低;25℃下,15.7%固体含量的支化PAN溶液的零剪切黏度(η0=3.52 Pa·s)仅为其同分子量的线型聚合物溶液黏度(η0=27.7 Pa·s)的12.7%。     

TiO_2(KH–570)-g-AN制备及其分子量的控制

将TiO2(KH–570)接枝丙烯腈(AN)制备TiO2(KH–570)-g-AN,并通过加入链转移剂控制分子量。通过实验,探讨出链转移剂用量、引发剂用量、反应时间、反应温度对接枝率及分子量的影响。并利用HF刻蚀处理TiO2,测试PAN黏均分子量大小。结果表明,反应温度为65℃,引发剂用量为单体AN质量的1.6%,链转移剂用量为单体AN质量的4%时分子量控制在8 000左右。     

催化链转移聚合法制备聚对甲基苯乙烯大分子单体

首次以钴Ⅱ肟氟化硼配合物(CoBF)催化剂、2,2′-偶氮二异丁腈(AIBN)为引发剂,由催化链转移聚合法制备聚对甲基苯乙烯大分子单体(poly(p-Methylstyrene)),考察不同CoBF的用量对相对分子质量的影响。结果表明:随着CoBF用量的增加,聚对甲基苯乙烯大分子单体的相对分子质量逐渐减小。另外,还采用了基于重均聚合度(DPw)的Mayo方程,计算出催化剂表观链转移常数(ct)为365.6。     

Preparation of polytetrahydrofuran monomethacrylate macromonomers by cationic ring‐opening polymerization of tetrahydrofuran

Polytetrahydrofuran monomethacrylate (MA‐PTHF) macromonomer was prepared by cationic ring‐opening polymerization(CROP) of tetrahydrofuran (THF) using boron trifloride etherate (BF₃ · OEt₂) as initiator and epichlorohydrin (ECH) as promoter. Two kinds of transfer agents were used: methacrylic acid (represented as TA1), and a mixture of methacrylic acid and sodium methacrylate (represented as TA2). The effects of polymerization conditions on molecular weight and molecular weight distribution of macromonomers were studied in this article, when the composition of reactants was kept constant. Under the same conditions, the molecular weight of macromonomer using TA2 is lower than that using TA1, which indicates that TA2 is more active than TA1. The molecular weight of MA‐PTHF macromonomer varies with the polymerization time before transfer agents were added (T1), but molecular weight distribution remains constant. When T1 is limited in 30 min, the apparent number‐average molecular weight of MA‐PTHF increases significantly with the increase of T1, and ranges from 5000 to 18,000. Hence, the molecular weight of MA‐PTHF macromonomer can be controlled by varying T1. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 810–815, 2000     

RAFT法制备窄分布温敏性PNIPAAm

以N,N-二甲基甲酰胺(DMF)为反应介质,偶氮二异丁氰(AIBN)、三硫代碳酸二(α,α′-二甲基-α-乙酸)酯(BDATC)作为链转移剂,使N-异丙基丙烯酰胺(NIPAAm)进行可逆加成—断裂链转移自由基(RAFT)聚合,考察了引发剂(I)与链转移剂(CAT)的浓度比对NIPAAm的RAFT反应结果的影响。结果表明:70℃下,当[CAT]0/[I]0介于20:1～5:1,均可得到分子量分布窄、分子量可控的PNIPAAm,说明其聚合过程符合活性聚合反应的特征。     

甲基丙烯酸二甲氨基乙酯的ATRP聚合

2-溴代异丁酸-Ⅳ-丁二酰亚胺酯（NHS—BIBA酯）由2-溴代异丁酸和,v-羟基丁二酰亚胺通过酯化反应制得。以它为引发剂,2,2＇-联吡啶（bpy）／CuBr为催化体系、水为溶剂,采用原子转移自由基聚合（ATRP）合成了带有功能基团的聚甲基丙烯酸二甲氨基乙酯（PDMAEMA）高分子。研究了引发剂、温度、反应时间、pH值和浓度对聚合产率的影响,利用凝胶渗透色谱（GPC）和核磁共振（1HNMR）测定了聚合物的分子量、多分散指数（PDI）和链结构。由GPC可知在最高产率下,Mn和Mw／Mn分别为8674和1．59,结果表明,NHS-BIBA酯引发的PDMAEMA实际数均分子量高于理论分子量,并具有低分散度,链结构上氢原子出峰符合特有的化学位移。     

P2VP-b-PS-b-PI三嵌段共聚物的RAFT合成及表征

以S-十二烷基-S’-(α,α’-二甲基-α’’-乙酸)-三硫代碳酸酯(DDMAT)为链转移剂,通过可逆加成-断裂链转移自由基聚合(RAFT)方法制备了窄分布的聚2-乙烯基吡啶。再以该聚合物为大分子链转移剂,引发苯乙烯的RAFT聚合,得到聚2-乙烯基吡啶-b-聚苯乙烯(P2VP-b-PS)的两嵌段共聚物。以P2VP-b-PS为RAFT试剂,合成聚2-乙烯基吡啶-b-聚苯乙烯-b-聚异戊二烯(P2VP-b-PS-b-PI)的三嵌段共聚物。运用1H NMR、IR和凝胶渗透色谱(GPC)等技术对产物的结构和分子量及分子量分布进行表征,采用原子力显微镜(AFM)观察三嵌段共聚物薄膜的微相分离结构。结果表明,所得三嵌段共聚物P2VP72-b-PS136-b-PI300分子量分布较窄(PDI=1.69),合成过程具有活性/可控聚合特征,聚合物薄膜经溶剂退火处理后出现了明显的微观相分离结构。     

Hydrogels for biomedical use based on 1-vinyl-2-pyrrolidone crosslinked with macromonomers

Macromonomers of various chain lengths with an average of three allyl double bonds per chain were prepared by anionic copolymerization of allyl methacrylate with methyl methacrylate. The macromonomers were characterized by gel permeation chromatography and nuclear magnetic resonance. The macromonomers were then copolymerized with 1-vinyl-2-pyrrolidone to form three-dimensional structures. Their optical, swelling and mechanical properties were studied and the crosslinking efficiency was determined. The copolymer properties are not greatly affected by macromonomer chain lengths up to 40-mers; above 50-mers there is a slight decrease in the equilibrium water content and a significant increase in the modulus of elasticity. The crosslinking efficiency depends on the macromonomer chain length; a marked increase was observed for the 50-mer because of a greater number of methyl-methyl interactions. Copolymers have favourable strength-strain properties and a low content of water-soluble extracts, in which the IR analysis demonstrated the presence of 1-vinyl-2-pyrrolidone homopolymers. In spite of the good results obtained for all the macromonomers described in this work, the 50-mer seems to be optimal for copolymerization with 1-vinyl-2-pyrrolidone.     

Synthesis of polyurethane graft copolymers by polyaddition reaction of dihydroxyl-terminated macromonomers

Summary Polyurethane-poly(methyl methacrylate) graft copolymers of well-defined structure and composition were synthesized by macromonomer method. Dihydroxyl-terminated macromonomer was prepared by radical polymerization of methyl methacrylate in the presence of -thioglycerol as a chain transfer agent. This dihydroxyl-terminated macromonomer and 1,4-butanediol were added to diisocyanate (hexamethylene diisocyanate or toluene-2,4-diisocyanate) catalyzed by di-n-butyltin dilaurate to produce tailor-made graft copolymers.     

Dispersion copolymerization of polyoxyethylene macromonomer and styrene. Part 3. Molecular characterization of polystyrene-graft-polyoxyethylene copolymers

Graft copolymers (polystyrene-graft-polyoxyethylene) (PS-graft-PEO) were prepared by the dispersion copolymerization of methacryloyl-terminated polyoxyethylene macromonomer and styrene initiated by an oil-soluble initiator (dibenzoyl peroxide, DBP). The apparent molecular weights of graft copolymers measured by size exclusion chromatography in tetrahydrofuran were found to be proportional to the -0·8th power of DBP concentration. This reaction order supports the termination of growing radicals by a first order radical loss process. The molecular weight distribution estimated from the size exclusion chromatography (SEC) data was found to decrease slightly with DBP concentration and to drop rapidly with macromonomer concentration. This was attributed to chain transfer events and to the increase of particle number: the higher the particle number the lower the monomer concentration in the particles. The bulkiness of the macromonomer molecules and the high segment density around the propagating reaction loci hinder the incorporation of macromonomer molecules into a copolymer growing chain. ©1997 SCI     

Graft polymerization of methyl methacrylate onto wool initiated by a hydrogen peroxide-sodium thiosulphate redox system. Part II kinetics and mechanism of the grafting reaction

Methyl methacrylate was grafted onto wool in the presence of an aqueous dioxane solution with a hydrogen peroxide-sodium thiosulphate initiator system, using the optimum conditions found in our previous paper¹⁹. It was stated that up to 90% conversion for the rate of reaction the following equation holds: \documentclass{article}\pagestyle{empty}\begin{document}${\rm R}_{\rm p} = - \frac{{{\rm d}\left[ {\rm M} \right]}} {{{\rm dt}}} = {\rm K} \cdot \left[ {\rm M} \right]^{1.5}$\end{document} where R_p is the overall rate of the graft polymerization, and [M] is the monomer concentration at the time t. The degree of polymerization of the isolated poly(methyl methacrylate) was found to be linearly proportional with the monomer concentration [M]. Investigations of the effect of the ratio of solvent to monomer concentration [S]/[M] on the reciprocal of the degree of polymerization showed that there was no chain transfer caused by the solvent dioxane. The number average molecular weight M?_n of the polymer separated from the grafted wool was found to be within the range of 3–15.9 × 10⁶ as determined by viscosimetry. The molecular weight distribution of the isolated poly(methyl methacrylate) samples was determined by turbidimetric titration. The following relationship was established between the volume fraction of the non-solvent, γ and the number average molecular weight M?ⁿ. of poly(methyl methacrylate): \documentclass{article}\pagestyle{empty}\begin{document}$\gamma = - 0.0285 + \frac{{50.54}}{{\sqrt[3]{{\overline M _n }}}}. $\end{document} The molecular weight distribution curves were found to be rather homogeneous indicating approximately the same chain length of the grafted poly(methy1 methacrylate) on the wool backbone. It was stated before³³ that the number average molecular weight could be determined from the inflection point of the turbidimetric curves. This method can be used for determining the molecular weight of all kinds of poly(methy1 methacrylate) occurring in practice.     

Molecular weight characteristics of 2-naphthyl methacrylate copolymers obtained by radical polymerization in different solvents

Summary The influence of the chemical nature of the polymerization medium on the molecular weight characteristics of the copolymers 2-naphthyl methacrylate/styrene and 2-naphthyl methacrylate/acrylonitrile was investigated by gel permeation chromatography. The results obtained show that the influence of the nature of the solvent used on the molecular weight characteristics could be attributed to the different chain transfer constants. The contribution of the monomer complexes which affects mainly the relative reactivity ratios of the comonomers may be neglected.Dedicated to Professor Ivan M. Panayotov to his 60. birthday with the best wishes