DEA接枝共聚物的制备及其温度响应行为

为改善合成聚合物聚N,N-二乙基丙烯酰胺(PDEA)的生物相容、生物降解性,在引发剂K2S2O8的作用下,将主单体N,N-二乙基丙烯酰胺(DEA)和改性单体丙烯酸(AA)接枝聚合到天然高分子羧甲基壳聚糖(CMCS)骨架上,考察反应条件对接枝共聚物接枝率、接枝效率和温度响应行为的影响。红外光谱仪表征共聚物结构,紫外/可见分光光度计检测不同条件下聚合物溶液的透光率。结果表明,当单体AA与DEA质量比为1∶50、单体总用量为1.5 g时,共聚物具有显著的温度响应行为,且相转变温度较高为31℃。     

PMMA-PTMA的合成及其催化分子氧氧化苯甲醇

通过电子转移活化再生催化剂原子转移自由基聚合法(ARGET ATRP)依次聚合单体甲基丙烯酸甲酯(MMA)和甲基丙烯酸-2,2,6,6-四甲基-4-哌啶基酯(TMPM),制得嵌段共聚物PMMA-PTMPM,再用3-氯过氧苯甲酸(mCPBA)将TMPM中的哌啶基氧化为2,2,6,6-四甲基哌啶氮氧自由基(TEMPO),得到负载链段为聚甲基丙烯酸甲酯的氮氧自由基嵌段共聚物PMMA-PTMA。通过红外光谱、核磁共振波谱、紫外可见分光光度计和凝胶渗透色谱等手段对共聚物进行表征。研究了嵌段共聚物在分子氧氧化体系下对伯醇的选择性催化氧化性能,并与均聚物PTMA和负载链段为聚乙二醇的氮氧自由基嵌段共聚物PEG-PTMA进行比较。结果表明,嵌段共聚物在分子氧氧化体系中催化性能良好,整体性能优于PTMA和PEG-PTMA,并且嵌段共聚物回收方便,可以实现重复使用。     

脂肪醇嵌段聚醚丙烯酸酯与丙烯酰胺共聚物及其水溶液特性的研究

本文合成了脂肪醇嵌段聚醚丙烯酸酯单体 ,并与丙烯酰胺共聚 ,得到共聚物PEPO PAM。芘荧光光谱分析表明 ,该聚合物在水溶液中依靠分子链上的疏水基团形成一定的缔合作用。PEPO PAM相对于部分水解聚丙烯酰胺 (HPAM )具有更好的增粘性。通过调整分子的组成 ,可使该聚合物不仅具有较强的增粘性 ,同时具有良好的水溶性。     

聚甜菜碱型疏水聚合物的合成及性能评价

以苯甲酰氯、丙烯酸、N,N-二甲基-1,3-丙二胺和氯乙酸为主要原料,合成了一种甜菜碱型功能单体丙烯酰胺丙基甜菜碱。丙烯酰胺丙基甜菜碱单体、丙烯酰胺、疏水单体进行三元共聚,得到聚甜菜碱型疏水聚合物,对聚合物溶液的抗盐性能进行了评价。结果表明,新型聚甜菜碱型疏水聚合物溶液具有优良的盐增稠性能。     

两性共聚物P(AM-co-SPE)的合成及盐溶液性质

以1,3-丙磺酸内酯和甲基丙烯酸N,N-二甲基氨基乙酯(DMAEMA)为原料,合成功能单体N,N-二甲基-N-甲基丙烯酰氧乙基-N-(3-磺丙基)铵甜菜碱(SPE),然后将该单体和丙烯酰胺(AM)进行自由基共聚反应,制备了两性共聚物P(AM-co-SPE),红外光谱表征了合成的功能单体及两性共聚物结构,探讨了聚合反应影响因素及两性共聚物在盐水中的黏度行为。结果表明,以过硫酸钾为引发剂,在聚合温度为60℃、引发剂用量为0.5%、单体SPE比例为10%时,获得两性共聚物特性黏数高达93mL·g~(-1);该两性共聚物在盐水中有明显增黏效果,且共聚物黏度随盐浓度增加而增大,尤其是在Ca~(2+)和Zn~(2+)盐溶液中增黏效果更佳,表现出明显的反聚电解质溶液性质。     

耐温耐盐疏水缔合聚合物的合成及性能评价

以丙烯酰胺(AM)、疏水单体烯丙基十二胺和耐盐单体H-66为原料,通过自由基水溶液聚合制备一种聚丙烯酰胺类聚合物RDTA。通过1H NMR和FTIR表征聚合物结构,通过表观黏度、SEM和流变性能测试研究了RDTA在不同溶液中的缔合效应和该缔合行为随温度变化的影响关系。实验结果表明,RDTA的临界缔合质量分数(W*)在0.25% ~ 0.3%。盐离子对RDTA高分子链的刺激作用能够增强该分子链的结构黏度。弹性模量G′随RDTA质量分数的增加而增大,溶液体系表现出弹性体,体系的空间结构更加密集。70℃、90℃和120℃,170 s-1剪切下,0.5% RDTA在6% NaCl盐溶液中剪切时间 < 300 s时,溶液黏度呈现缓慢上升趋势,说明RDTA在NaCl盐溶液中存在盐刺激RDTA溶液增稠的现象,继续剪切1 h后,剪切剩余黏度仍60 mPa·s以上。     

应用FRAP技术评价蛋白在聚丙烯酰胺-丙烯酸凝胶中的扩散行为

药物分子从药物载体中的释放行为与载体的结构有密切关系.本实验中采用丙烯酰胺和丙烯酸等材料,运用水相沉淀的方法,制备了4种不同单体配比的聚丙烯酰胺-丙烯酸(P(Am-co-Ac))共聚物水凝胶.运用红外分析方法对P(Am-co-Ac)组成进行表征.使用荧光漂白恢复法(FRAP,fluorescence recovery after photobleaching)观察荧光素FITC标记的牛血清白蛋白(BSA)在聚丙烯酰胺-丙烯酸中的扩散行为,并以激光共聚焦显微镜进行实时成像.实验表明,FITC-BSA在不同单体配比的共聚物中的扩散系数是不同的.通过调节聚合物中单体的配比能够达到控制蛋白释放速率的作用,从而为调控蛋白和多肽类药物的缓控释放提供了可能性.     

氟代丙烯酸酯共聚物的合成及溶液性能

以甲基丙烯酸十二氟庚酯(FA)和甲基丙烯酸(MAA)为单体,偶氮二异丁腈(AIBN)为引发剂,二氧六环为反应介质,制备了氟代丙烯酸酯共聚物。聚合条件为:聚合温度75℃,单体量比n(FA)∶n(MAA)=(1∶9)~(4∶6),单体的质量分数w(FA+MAA)=25%,引发剂AIBN为单体总质量的1.5%。用红外光谱、核磁共振氢谱、元素分析、示差扫描量热分析、热重分析和凝胶渗透色谱对产物结构进行了确认和表征。研究了共聚物溶液的性质。结果表明:该聚合物具有聚电解质的黏度行为,在纯水中其比浓黏度随溶液质量浓度的降低而增加;在纯水中聚合物具有表面活性,其表面活性随着聚合物结构中氟碳链质量分数的增加而提高,该聚合物可以用作制革生产中的防水复鞣剂。     

丙烯酸十二酯共聚物稠化能力的试验研究

聚(甲基)丙烯酸酯或丙烯酸高级酯与其它一些单体的共聚物是一类优良的油品增粘-降凝双效剂。丙烯酸十二酯与第二单体A的共聚物对润滑油有较好的降凝效果。丙烯酸十二酯与第二单体A的共聚物对润滑油也应有较好的增粘作用(即稠化能力)。用四种溶剂分别采用溶液聚合方法,用正交试验法对丙烯酸十二酯与第二单体A进行共聚试验,共聚物以1%的添加量加入到润滑油基础油中,做调合油的粘度测定,以增比粘度、粘温指数Q和粘度指数VI为考察目标,探讨丙烯酸十二酯与第二单体A共聚物对润滑油基础油的稠化能力,并找出较好的共聚条件。试验结果表明:丙烯酸十二酯与第二单体A共聚物对润滑油确有较好的增粘和改变油品粘温性能的作用,是一种增粘-降凝双效添加剂。     

分散聚合共聚物PAM-DMC的室内性能研究

以丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,二乙二醇丁醚为分散剂,过硫酸铵和亚硫酸氢钠氧化还原体系为引发剂,利用一种分散聚合技术得到稳定的阳离子型聚丙烯酰胺(PAM-DMC)乳液。利用傅里叶红外光谱仪(FT-IR)、X射线衍射(XRD)、热重分析(TG)及紫外分光光度计(UV)对合成的共聚物结构进行表征,并对PAM-DMC乳液进行透射电镜(TEM)、稳定性分析与絮凝性能的测试。结果表明,共聚物PAM-DMC为无定形态的非结晶分子,且热稳定性好,动力学不稳定指数(TSI)≤0. 13,且其为100～500 nm的球形或椭球形颗粒,平均粒径为198. 6 nm。当分子质量为1. 85×10~6、聚合物絮凝率达到最大值时,溶解时间为156 min,阳离子度为7. 59%,特性黏度为498. 24 Pa·s。     

HPAM-g-P(NIPA-co-DMAM)的合成与温敏行为

利用端基转换法合成了不同组成及相对分子质量的端丙烯酰胺基聚（N-异丙基丙烯酰胺-co-N,N-二甲基丙烯酰胺）［poly(NIPA-co-DMAM), PID］大分子单体;与丙烯酰胺聚合后再水解，得到以PID为侧链，浊点在37～63℃的接枝共聚物［HPAM-g-P(NIPA-co-DMAM), HGPID］。利用¹H NMR及端基分析等对大分子单体和接枝物的组成及结构进行了表征;考察了接枝共聚物侧链的组成和链长、共聚物质量浓度和外加盐浓度等因素对其水溶液的热敏特性及温敏增稠性的影响。     

Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm³⁺, Nd³⁺, and La³⁺ than for Cu²⁺, Ni²⁺ and Co²⁺. The APPA–NIPAAm (10:90) copolymer/metal (Sm³⁺, Nd³⁺, or La³⁺) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu²⁺,Ni²⁺, or Co²⁺) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004     

Synthesis and thermal responsive properties of P(LA-b-EO-b-PO-b-EO-b-LA) block copolymers with short hydrophobic poly(lactic acid) (PLA) segments

Poly(lactic acid) (PLA) was successfully grafted to both ends of Pluronic F87 block copolymer (PEO-PPO-PEO) to obtain amphiphilic P(LA-b-EO-b-PO-b-EO-b-LA) block copolymers (PLA-F87-PLA) with short PLA blocks. The block composition and structure of PLA-F87-PLA block copolymers were studied by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetric (DSC) and wide angle X-ray diffraction (WXRD) techniques. The aggregation behavior of PLA-F87-PLA block copolymers in aqueous solutions was studied using the laser light scattering (LLS) technique. Various types of particles consisting of small micelles, medium and large aggregates were observed due to the complex structure of these copolymers. Importantly, PLA-F87-PLA block copolymers retain the thermal responsive behavior found in Pluronic systems. The critical micellization temperatures (CMTs) of PLA-F87-PLA were lower than that of F87 because of increased hydrophobicity introduced by the PLA blocks. A reversible sol-gel transition was observed for the hydrogels formed from PLA₆-F87-PLA₆ and PLA₉-F87-PLA₉ block copolymers. Preliminary results from the drug release study using a hydrophilic model drug procain hydrochloride (PrHy) were promising. Constant initial release rate was observed.     

pH- and temperature-responsive amphiphilic diblock copolymers of 4-vinylpyridine and oligoethyleneglycol methacrylate synthesized by RAFT polymerization

Diblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block.     

Synthesis,characterization, and aqueous solution behavior of copolymers of acrylamide and sodium 10-acryloyloxydecanoate

A new water-soluble monomer of sodium 10-Acryloyloxydecanoate (NaAD), which possesses a hydrophobic group and an ionizable group, was synthesized from acryloyl chloride and 10-hydroxydecanoic acid, and the series of copolymers of NaAD with acrylamide (AM) were prepared by the free radical polymerization in aqueous solution using ammonium persulfate as the initiator. The feed ratio of NaAD:AM was varied from 5:95 to 70:30 mol%, with the total monomer concentration held constant at 0.5 M. The copolymer compositions were determined from elemental analysis. The molecular weights of the copolymers were determined by gel permeation chromatography ranged from 0.76 × 10⁶ to 1.37 × 10⁶ g/mol. All copolymers were soluble in deionized water and salt solutions at pH > 5. The dilute and semidilute solution behavior of the copolymers was studied as a function of composition, pH, and added electrolytes, and the results indicated that NaAD30 exhibited much higher viscosity values. At moderate pH values, the copolymers coils become slightly more expanded and intermolecular association interactions occur, which was indicated by fluorescence and apparent viscosity measurements. Upon the addition of NaCl and in low pH, viscosities tended to decrease because of the disruption of the intermolecular associations.     

Synthesis and characterization of itaconic anhydride and stearyl methacrylate copolymers

The free-radical copolymerization and the properties of comb-like copolymers derived from renewable resources, itaconic anhydride (ITA) and stearyl methacrylate (SM), are described. The ITA-SM copolymers were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The melting point (T_m) of the side-chains and the crystallinity decreased with increasing ITA concentration. The crystalline side-chains suppressed molecular motion of the main chain, so that a glass transition temperature (T_g) was not resolved unless the ITA concentration was sufficiently high so that T_g > T_m. The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased.     

聚(丙烯腈/醋酸乙烯酯)/蒙脱土纳米复合材料的流变性能

研究了聚(丙烯腈/醋酸乙烯酯)/蒙脱土[P(AN/VAc)/Clay]纳米复合材料的溶解特性及其在二甲基乙酰胺(DMA)溶剂中的流变性能。结果表明,P(AN/VACc)/Clay在溶液纺丝时最佳的溶剂为DMA; P(AN/VAc)/Clay-DMA溶液的非牛顿流动指数小于1,溶液为假塑性流体;当溶液质量分数为12%-13%、温度为130-150℃时,P(AN/VAc)/Clay-DMA溶液的纺丝性能最佳     

Phase behavior of temperature‐ and pH‐sensitive poly(acrylic acid‐g‐N‐isopropylacrylamide) in dilute aqueous solution

Several different composition temperature‐ and pH‐sensitive poly(acrylic acid‐g‐N‐isopropylacrylamide) (P(AA‐g‐NIPAM)) graft copolymers were synthesized by free‐radical copolymerization utilizing macromonomer technique. The phase behavior and conformation change of P(AA‐g‐NIPAM) in aqueous solutions were investigated by UV–vis transmittance measurements, fluorescence probe, and fluorescence quenching techniques. The results demonstrate that the P(AA‐g‐NIPAM) copolymers have temperature‐ and pH‐sensitivities, and these different composition graft copolymers have different lower critical solution temperature (LCST) and critical phase transition pH values. The LCST of graft copolymer decreases with increasing PNIPAM content, and the critical phase transition pH value increases with increasing Poly(N‐isopropylacrylamide) (PNIPAM) content. At room temperature (20°C), different composition of P(AA‐g‐NIPAM) graft copolymers in dilute aqueous solutions (0.001 wt %) have a loose conformation, and there is no hydrophobic microdomain formation within researching pH range (pH 3 ～ 10). In addition, for the P(AA‐g‐NIPAM) aqueous solutions, transition from coil to globular is an incomplete reversible process in heating and cooling cycles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electrostatic self-assembly of thermally responsive zwitterionic poly(N-isopropylacrylamide) and poly(ethylene oxide) modified with ionic groups

The electrostatic self-assembly of thermally responsive copolymers of N-isopropylacrylamide (NIPAM) containing up to 10 mol% of the sulfobetaine monomer 3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropane sulfonate) (SPP) and poly(ethylene oxide) modified with terminal cationic or anionic groups (IMPEO) was studied in methanol and aqueous solutions by static light scattering, turbidimetry, viscometry, and rheological measurements. The formation of graft-like complexes at stoichiometric dipole-ion ratio and their self-association was detected in the dilute and semidilute regime at temperatures below and above the lower critical solution temperature (LCST). The ability of the graft-like complexes to associate below the LCST depended on the sulfobetaine content of the copolymers, the functionality of IMPEO, and the polymer concentration. The effect of the IMPEO terminal group on the solution behavior of the graft-like complexes was less pronounced. With increasing temperature their semidilute aqueous solutions form gels, stable over a wide temperature range.     

Synthesis and swelling behavior of pH- and temperature-sensitive poly[2-(dimethylamino)ethyl methacrylate-co-2-acrylamido-2-methylpropane-1-sulfonic acid] hydrogels

Summary Poly[2-(dimethylamino)ethyl methacrylate-co-2-acrylamido-2-methylpropane-1-sulfonic acid], poly(DMAEMA-co-AMPS), hydrogels were prepared by chain polymerization in water at 60 °C in the presence of tetraethyleneglycol diacrylate (TEGDA) as crosslinking agent. Ammonium persulfate (APS) and N,N,N’,N’-tetramethylethylenediamine (TEMED) were used as initiator and accelerator, respectively. Hydrogels with different feed compositions were prepared by keeping the total monomer concentration constant at 1 or 0.5 M. The concentration of TEGDA in the feed was adjusted so that it made for 3 or 2 mol % of the total monomer content while it was 1% for APS. In order to observe the effects of pH and ionic strength of the medium on swelling, the equilibrium swelling behavior of these hydrogels were investigated both in distilled water at various temperatures between 30 and 90 °C and in different buffer solutions with pH of 2.8, 5.3, 7.0, 10.0, and 12.4 at constant ionic strength (I=0.08 mol/l) at room temperature. The effects of temperature and co-monomer AMPS content on the swelling behavior of poly(DMAEMA-co-AMPS) in distilled water were also investigated. The copolymers with equimolar contents of DMAEMA and AMPS displayed minimum swelling both in distilled water and in buffer solutions due to ionic complex formation. Their swelling values in distilled water between 30 and 90 °C were constant. While equilibrium swelling values of copolymers in buffer solutions with pH between 2.8 and 7 were almost constant, they increased with increasing pH. The increase in the AMPS content and decrease in initial monomer concentration increased the equilibrium swelling values of copolymers.