Synthesis of block copolymers containing poly(ferrocenylmethyl methacrylate) units

Ferrocenylmethyl methacrylate (FMMA) has been polymerized by using LiAlH₄–tetramethyl-ethylenediamine initiation to form living polymers in high vacuum systems. The addition of methyl methacrylate or acrylonitrile to these living systems gave the block copolymers FMMA-block MMA and FMMA-block AN. The anions were not nucleophilic enough to initiate styrene polymerization. Therefore, living polystyrene was prepared (sodium naphthalide initiation in THF at ?78°C) and upon FMMA addition, styrene-block FMMA copolymers were formed. Extraction, precipitation, and gel-permeation chromatography studies were performed to examine the purity of the block copolymers.     

Synthesis and properties of poly(butylene terephthalate)-poly(ethylene oxide)-poly(dimethylsiloxane) block copolymers

Poly(butylene terephthalate)-poly(ethylene oxide)-poly(dimethyl siloxane)-poly(ethylene oxide) block copolymers, (PBT-PEO-PDMS-PEO)_m, are synthesized by polycondensation (PC) of dimethylterephtalate (DMT), 1,4-butanediol (BDO) and PEO-PDMS-PEO. The soft block has been incorporated from 10 to 70 wt-%; the total molecular weight (MW) of the block-copolymers amounts to 16000 - 20000 g/mol. One major problem of polyether-PBT thermoplastic elastomers is their poor thermo-oxidative stability. Due to the excellent heat stability of PDMS, the resistance of this new thermoplastic elastomer against thermo-oxidative degradation has been increased 80 %! From differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the PEO-PDMS-PEO based COPEs, three phases can be distinguished. Besides the crystalline PBT phase, an amorphous mixed phase of PBT and PEO and an almost pure PDMS phase have been found. Due to the high concentration of the mixed PBT-PEO phase, the low temperature modulus and the glass transition temperature, T_g, are not dominated by the pure PDMS phase (T_g = −114°C). Depending on the amount of PBT and PEO present, the main glass transition lies in the range of −50°C to 50°C.     

Amphiphilic block copolymers containing thermally degradable poly(phthalaldehyde) blocks

In this study, the preparation of a new class of amphiphilic block copolymers consisting of a poly(phthalaldehyde) (PPA) block and hydrophilic poly(alkylene oxide) blocks is described. PPA was prepared by ionic cyclopolymerization. A telechelic polymer block was prepared by endcapping of the PPA by a bifunctional reagent carrying isocyanate and isothiocyanate groups. As the second block, monoamino‐terminated poly(alkylene oxide)s (Surfonamines®, also known as Jeffamines®) were chosen. These polymers could be readily coupled to the PPA telechel and gave amphiphlic, mainly ABA‐type block copolymers. The PPA block of these products can be selectively depolymerized at moderate temperature. The block copolymers were characterized by dual‐detection size exclusion chromatography, and the defined and stepwise thermal decomposition of the two different block types were shown by thermogravimetric analysis. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1499–1509, 2009     

Synthesis and characterization of semicrystalline cycloaliphatic polyester/poly(dimethylsiloxane) segmented copolymers

High molecular weight poly(dimethylsiloxane)/semicrystalline cycloaliphatic polyester segmented copolymers based on dimethyl-1,4-cyclohexane dicarboxylate were prepared and characterized. The copolymers were synthesized using a high trans content isomer that afforded semicrystalline morphologies. Aminopropyl-terminated poly(dimethylsiloxane) (PDMS) oligomers of controlled molecular weight were synthesized, end capped with excess diester to form a diester-terminated oligomer, and incorporated via melt transesterification step reaction copolymerization. The molecular weight of the polysiloxane and chemical composition of the copolymer were systematically varied. The polysiloxane segment was efficiently incorporated into the copolymers via an amide link and its structure was unaffected by low concentrations of titanate transesterification catalyst, as shown by control melt experiments. The homopolymer and copolymers were characterized by solution, thermal, mechanical, and surface techniques. The segmented copolymers were microphase separated as determined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and by transmission electron microscopy (TEM). It was demonstrated that relatively short poly(dimethylsiloxane) segment lengths and compositions were required to maintain single phase melt polymerization conditions. This was, in fact, the key to the successful preparation of these materials. The copolymers derived from short poly(dimethylsiloxane) segments demonstrated good mechanical properties, melt viscosities representative of single phase polymer melts, and were easily compression molded into films. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3495–3506, 1997     

Synthesis and endosomolytic properties of poly(amidoamine) block copolymers

The poly(amidoamine)s (PAAs) ISA 1 and ISA 23 display pH-dependent conformational change and pH-dependent membrane perturbation. These properties confer potential for use as endosomolytic polymers for intracytoplasmic delivery of toxins and genes. Both polymers are relatively non-toxic, and moreover ISA 23 has the beneficial property in vivo, of being non hepatotropic when administered intravenously. Although ISA 23 and ISA 1 demonstrate ability to transfect cells, ISA 1 is also able to promote intracellular delivery of non-permeant toxins. The aim of this study was to synthesise random and block copolymers of ISA 1 and ISA 23 and investigate whether these second generation hybrids would allow optimisation of PAA biological characteristics. Random and block copolymers of ISA 1 and ISA 23 were synthesised by hydrogen transfer polyaddition to generate a library of PAAs with an ISA 23:ISA 1 molar ratios of 2:1 to 4:1. The resultant polymers have a pI slightly below 7.4 and a M(w) of 19,900-49,000 g/mol and a M(n) of 13,100-24,100 g/mol. Whereas none of the random or block copolymers were haemolytic at pH 7.4 all demonstrated pH-dependent membrane activity. At pH 5.5 they caused 50-60% haemoglobin (Hb) release over 1 h. This was slightly less than that seen for ISA 23 (80% Hb release). None of the copolymers were cytotoxic against B16F10 cells during a 72 h incubation (IC(50) > 2 mg/ml; MTT assay). The ability of the random and block copolymer PAAs to deliver the toxin gelonin was also examined, but only ISA 1 and the block copolymer B2 (ISA 23:ISA 1 at a 2:1 molar ratio) were able to promote intracellular delivery, as measured by cytotoxic activity. It would be interesting to study the body distribution of B2 and determine whether this toxin-delivering PAA is able to escape liver capture.     

Synthesis,liquid crystalline mesophases and morphologies of diblock copolymers composed of a poly(dimethylsiloxane) block and a nematic liquid crystalline block

In this study, a series of liquid crystalline diblock copolymers, composed of a soft poly(dimethylsiloxane) (PDMS) block with a de?ned length and a side-on liquid crystalline poly(3??-acryloyloxypropyl 2,5-di(4?-butyloxybenzoyloxy) benzoate) (P3ADBB) block with different lengths, are synthesised by the atom transfer radical polymerisation. The macromolecular structures, liquid crystalline properties and the microphase-separated morphologies of the diblock copolymer are investigated by ¹H NMR, FT-IR, GPC, POM, DSC and TEM. The results show that the well-de?ned diblock copolymers (PDMS_n-b-P3ADBB_m) possess four different soft/rigid ratios (n = 58, m = 10, 25, 42, 66) and relatively narrow molecular distributions (PDI ≤ 1.30). P3ADBB blocks of the copolymers show nematic sub-phases, which are identical to the mesomorphic behaviour of the homopolymer P3ADBB. After being annealed at 90°C in a vacuum oven for 48 h, the copolymers form a lamellar morphology when m = 10 and morphologies of PDMS spheres embedded in P3ADBB matrix when m = 25, 42 and 66.     

Synthesis of rod-coil block copolymers via end-functionalized poly(p-phenylene)s

This paper describes a new way to synthesize rod-coil block copolymers consisting of poly(p-phenylene) (PPP) as rigid rod and either polystyrene (PS) or poly(ethylene oxide) (PEO) as flexible coil. The Suzuki-coupling of the AB-type monomer 4-bromo-2,5-diheptylbenzeneboronic acid (1) under strictly proton-free conditions leads to the control of PPP endgroups and hence allows the synthesis of a variety of differently end-functionalized poly(p-phenylene)s. The poly(2,5-diheptyl-p-phenylene)-block-polystyrene (7) is then prepared via condensation via condensation of anionically polymerized living polystyrene ( 6 ) with α-(4-formylphenyl)-ω-phenyl-poly(2,5diheptyl-p-phenylene) ( 4 ). Toluenesulfonic acid catalyzed condensation of α-methyl-ω-amino-poly(oxyethylene) ( 8 ) with PPP 4 yields poly(2,5-diheptyl-p-phenylene)-block-poly(ethylene oxide) ( 9 ).     

Synthesis and characterization of fluorinated poly(imide siloxane) block copolymers

Five new block copoly(imide siloxane)s have been prepared by reacting two different diamines, 4,4″-bis(p-aminophenoxy)-3,3″-trifluoromethyl terphenyl (APTTFT) and amino-propyl terminated polydimethylsiloxane (APPS), separately with 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride); BPADA. The reactions were conducted by a two pot solution imidization technique. The diamine APTTFT and the dianhydride BPADA composed the hard block segment while APPS and BPADA composed the soft block segment. The soft and hard blocks of different block lengths were generated by different stoichiometric imbalance in two different flasks and the final polymers were obtained by reacting both the blocks together. Different block copoly(imide siloxane)s were prepared on increasing the hard block lengths (DP) from 7 to 12, 18, 23 and 28 and the soft block lengths (DP) from 4 to 6, 8, 10 and 12, respectively. The resulting polymers have been well characterized by NMR, DSC and DMA techniques. The properties of the block copolymers were compared with the analogous random copolymers and homopolyimide prepared without APPS.     

Synthesis and micellar behavior of poly(acrylic acid-b-styrene) block copolymers

Poly(acrylic acid-b-styrene) (PAA-b-PS) amphiphilic block copolymers were synthesized by consecutive telomerization of tert-butyl acrylate, atom transfer radical polymerization (ATRP) of styrene, and hydrolysis. The resulting block copolymers were characterized by ¹H NMR and GPC. These amphiphilic block copolymeric micelles were prepared by dialysis against water. Transmission electron micrograph (TEM) and laser particle sizer measurements were used to determine the morphology and size of these micelles. The results showed that these amphiphilic block copolymers formed spherical micelles with average size of 140–190?nm. The critical micelle concentration (CMC) and the kinetic stability of these micelles were investigated by fluorescence technique, using pyrene as a fluorescence probe. The observed CMC value was in the range of 0.075–0.351?mg/L. Kinetic stability studies showed that the stability of micelles increased with the decrease of the pH value of the solution.     

Synthesis of polybutadiene‐graft‐poly(dimethylsiloxane) and polyethylene‐graft‐poly(dimethylsiloxane) copolymers with hydrosilylation reactions

We report preliminary results for the synthesis of polyethylene‐graft‐poly(dimethylsiloxane) copolymers obtained by catalytic hydrogenation of polybutadiene‐graft‐poly(dimethylsiloxane) copolymers (PB‐g‐PDMS). These last copolymers were synthesized by hydrosilylation reactions between commercial polybutadiene and ω‐silane poly(dimethylsiloxane). The reaction was carried in solution catalyzed by cis‐dichloro bis(diethylsufide) platinum(II) salt. The PB‐g‐PDMS copolymers were analyzed by ¹H and ¹³C NMR spectroscopies, and the relative weight percentages of the grafted poly(dimethylsiloxane) macromonomer were determined from the integrated peak areas of the spectra. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2920–2930, 2004     

Synthesis and characterization of model diblock copolymers of poly(dimethylsiloxane) with poly(1,4‐butadiene) or poly(ethylene)

Model diblock copolymers of poly(1,4‐butadiene) (PB) and poly(dimethylsiloxane) (PDMS), PB‐b‐PDMS, were synthesized by the sequential anionic polymerization (high vacuum techniques) of butadiene and hexamethylciclotrisiloxane (D₃) in the presence of sec‐BuLi. By homogeneous hydrogenation of PB‐b‐PDMS, the corresponding poly(ethylene) and poly(dimethylsiloxane) block copolymers, PE‐b‐PDMS, were obtained. The synthesized block copolymers were characterized by nuclear magnetic resonance (¹H and ¹³C NMR), size‐exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and rheology. SEC combined with ¹H NMR analysis indicates that the polydispersity index of the samples (M_w/M_n) is low, and that the chemical composition of the copolymers varies from low to medium PDMS content. According to DSC and TGA experiments, the thermal stability of these block copolymers depends on the PDMS content, whereas TEM analysis reveals ordered arrangements of the microphases. The morphologies observed vary from spherical and cylindrical to lamellar domains. This ordered state (even at high temperatures) was further confirmed by small‐amplitude oscillatory shear flow tests. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1579–1590, 2006     

Synthesis and aggregation of poly(valine)‐poly (ethylene glycol) block copolymers

The solubility nature of many medicines presents a challenge for successful delivery of these drugs to the body. Polymeric carriers are potentially viable as vessels for both the protection and transport of these medicinal substances. In an effort to generate polymeric materials for this desired application, A‐B‐A triblock copolymers have been synthesized with a central block composed of hydrophilic poly (ethylene glycol) (PEG) and flanking hydrophobic sequences composed of five valine units terminated with end groups of varying hydrophobicity. These copolymers were constructed by adding amino acids stepwise to the hydrophilic block using solution phase chemistry. The self‐assembly behavior of all polymers was investigated using fluorimetry with a pyrene probe. In general, copolymers with more hydrophobic end groups exhibited lower critical aggregation concentrations (CACs). Fmoc‐terminated copolymers displayed the lowest CAC of 0.032 mg/mL and demonstrated little cytotoxicity when exposed to SW620 colorectal cancer cells. Transmission electron micrographs show the presence of multiple compartments within these spherical assemblies, which may prove useful in encapsulating medicinal substances. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5381–5389, 2008     

Synthesis and characterization of multiblock copolyesters containing poly(dimethylsiloxane) in the soft segments

Synthesis and thermal properties of poly(aliphatic/aromatic-ester) copolymers containing additionally poly(dimethylsiloxane) (PDMS) chains in the soft segments are discussed. A two step method of transesterification and polycondensation from the melt was carried out in a presence of magnesium-titanate catalyst. An aliphatic dimer fatty acid was used as a component of the soft segments while poly(butylene terephthalate) (PBT) constituted the hard blocks. Effectiveness of the incorporation of PDMS into polymer chain was confirmed by the Soxhlet extraction and infrared spectroscopy of an excess of 1,4-butane diol destilled off from the polycondensation reaction. Multiblock copolymers showed microphase separation as determined by differential scanning calorimetry. Incorporation of a small amount of PDMS (up to 14.5 wt.-%) into polymer chain containg low concentration of hard segments of PBT lead to decrease in crystallinity of such copolymers. This may indicate that semicrystalline PBT are dissolved in the amorphous matrix of the soft segments.     

Crystallization of poly(tetramethyl-p-silphenylene–dimethylsiloxane) (TMPS–DMS) block copolymers: Morphology and kinetics

The crystallization behavior of random block copolymers of (tetramethyl-p-silphenylenesiloxane) and dimethylsiloxane has been studied over a wide range of temperature and composition. The copolymer melting temperature, glass transition temperature, rate of crystallization, crystallinity, and density decrease in magnitude as the dimethylsiloxane block content are raised in this two-component system. The crystal end-surface (interfacial) energy increases as the dimethylsiloxane mole fraction decreases in accord with other morphological observations. The morphological changes observed in these copolymers are consistent with the conclusions deduced from the crystallization kinetics. Negatively, birefringent spherulites are observed over the entire crystallization range investigated.     

Synthesis of poly(p-dioxanone)-based block copolymers in supercritical carbon dioxide

Poly(p-dioxanone)–poly(ethylene glycol)–poly(p-dioxanone) triblock copolymers (PPDO–PEG–PPDO) were first synthesized by suspension ring-opening polymerization (ROP) of p-dioxanone (PDO) in supercritical carbon dioxide (scCO₂) using different molecular weights (2–10 K) of poly(ethylene glycol) (PEG) as macroinitiators. White and fine flow powders were successfully obtained when the molecular weight of PEG was below 6 K and its feed content below 20 wt.%. The ¹H nuclear magnetic resonance (NMR) result indicated the formation of PPDO–PEG–PPDO block structure even in a confined polymerized environment of particles. All the powderous samples contained irregular shaped particles that were observed by scanning electron microscope (SEM). Except for the copolymer with 10 wt.% PEG10K feed content, the mean particle sizes of other powderous samples showed identical values close to 15 μm. This fact was in agreement with the crystallinity of PPDO in the copolymers measured by differential scanning calorimetry (DSC). The water absorption of these copolymers was also measured, and as compared with PPDO homopolymer, the introduction of PEG increased the water absorption of the copolymers. The green and environmentally friendly method disclosed in this work is attractive to directly synthesize biodegradable polymeric particles with potential biomedical applications.     

Biodegradable microspheres containing poly(epsilon-caprolactone)-Pluronic block copolymers for temperature-responsive release of proteins

Temperature-responsive microspheres were fabricated for the purpose of releasing protein in responsive to surrounding temperature changes. Temperature-responsive polymer, Pluronic was synthesized into block copolymers of poly(epsilon-caprolactone)-Pluronic with two different chain lengths of poly(epsilon-caprolactone). Microspheres loaded with proteins were prepared by a W/O/W emulsion method. The surface morphology was examined by scanning electron microscopy, showing that microspheres with diblock copolymers had porous structures due to hydrophilicity of Pluronic blocks. After incubating the microsphere at 37 degrees C for 7 days, temperature-responsive protein release was monitored with alternating temperature changes between 20 and 37 degrees C. The protein release was attenuated when the microsphere was incubated at 20 degrees C but the release rate was recovered at 37 degrees C, confirming variable release rate according to the temperature changes. The variable release rate of protein was dependent on the length of poly(epsilon-caprolactone) blocks attached to Pluronic.     

交联型聚芳醚砜两亲嵌段聚合物的合成与表征

首先分别合成了主链上含有查尔酮结构的疏水段和侧链上含有叔胺的亲水段,然后通过疏水段与亲水段的末端缩合反应合成了一系列光敏性聚芳醚砜两亲嵌段聚合物,其结构和热性能分别通过1 H NMR,FT-IR,UV-Vis光谱,TGA和万能力学试验机等进行表征测试.该两亲性嵌段聚合物具有良好的溶解性、热稳性、力学性能和光敏性,在紫外光谱322nm处有最大吸收峰,在常温下经紫外光照射,分子链之间发生[2+2]环加成反应,聚合物分子之间形成交联结构,最大交联度可达到64%.     

Synthesis and characterization of ferrocene containing block copolymers

Narrowly dispersed diblock copolymers containing poly(methyl methacrylate) [PMMA] or poly(nonafluorohexyl methacrylate) [PF9MA] as the first block and poly(ferrocenylmethyl methacrylate) [PFMMA] as the second block, were prepared by anionic polymerization for the first time. Disordered bulk morphologies in the case of PMMA‐b‐PFMMA were observed and explained in terms of low Flory–Huggins interaction parameter (χ ≤ 0.04). In the case of PF9MA‐b‐PFMMA hexagonally packed cylinder morphology (HEX) was substantiated from TEM and SAXS observations. Furthermore, high incompatibility between PF9MA and PFMMA blocks allowed for the formation of well‐ordered ferrocene containing cylinders on silica substrate upon exposure of the thin films to a saturated solvent vapor. It was shown that the cylinder orientation, parallel or perpendicular to the surface, could easily be controlled by appropriate choice of the solvent and without the need for preliminary surface modification, for example by means of grafted brush layer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 495–503