Surface grafting of polymer onto carbon thin film

The surface grafting of polymers onto carbon thin film deposited on a glass plate was achieved by two methods: the graft polymerization initiated by initiating groups introduced onto the surface; and the trapping of polymer radicals by surface aromatic rings of the thin film. It was found that the radical and cationic graft polymerization of vinyl monomers are initiated by azo and acylium perchlorate groups introduced onto the surface, respectively, and the corresponding polymers are grafted onto the surface: the surface grafting of polymers were confirmed by the contact angle of the surface with water. In addition, the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by potassium carboxylate groups on the carbon thin film to give the corresponding polyester-grafted carbon thin film. On the other hand, polymer radicals formed by the decomposition of azo polymer, such as poly(polydimethylsiloxane-azobiscyanopentanoate) and poly(polyoxyethylene-azobiscyanopentanoate), were successfully trapped by the surface aromatic rings of carbon thin film and polydimethylsiloxane and polyoxyethylene were grafted onto the surface. © 1995 John Wiley & Sons, Inc.     

Investigations on synthesis and polymerization of difunctional 7-membered cyclic ketenacetals

Summary. The synthesis of difunctional seven-membered cyclic ketenacetals was investigated and the new monomers were characterized by IR-, NMR-spectroscopy, and elemental analysis. It was shown that the bifunctional ketenacetal 5 undergoes a radical homopolymerization forming crosslinked polymers with a high degree of ring-opened units. The copolymerization of the difunctional ketenacetal 5 with the monofunctional ketenacetal 1 leads only to low molecular polymers. Received: 9 May 1997/Revised: 4 July 1997/Accepted: 10 July 1997     

Metallopolymers with transition metals in the side-chain by living and controlled polymerization techniques

Work on side-chain transition metal-containing polymers prepared by controlled and living polymerizations is summarized, including living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). These polymers include metallocene-containing polymers, ferrocenylsilane polymers with additional metal at the side chain, metal carbonyl complex polymers, and ligated metal complex polymers.     

Synthesis and radical scavenging ability of new polymers from sterically hindered phenol functionalized norbornene monomers via ROMP

Norbornene derivatives, including four novel structure compounds, bearing sterically hindered phenol (SHP) were prepared as functional monomers (1-3). The ring-opening metathesis polymerization (ROMP) of these functional monomers was carried out with typical ruthenium catalyst [bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride] that was so called as first-generation Grubbs catalyst to prepare hindered phenol functionalized polymers possessing radical scavenging function. The resulting polymers were characterized by means of gel permeation chromatography (GPC), ¹H and ¹³C NMR, and differential scanning calorimetry (DSC). The radical scavenging ability of polymer was evaluated by determining RSA using the α,α-diphenyl-β-picrylhydrazyl (DPPH) free radical. The results show that the resulting polymers have different radical scavenging ability with the difference in structure of side chain. Polymers bearing 3,5-di-tert-butyl-4-hydroxyphenyl-propionate (DBHP) side chain have a higher radical scavenging ability than the polymers bearing 3,5-di-tert-butyl-4-hydroxy-benzoate (DBHB) as side chain. The molecular weight of polymers is dependent on the ratio of molar concentration of monomer to catalyst ([M]/[C]); monomers bearing DBHP group have a higher activity for ROMP than the monomers bearing DBHB group comparatively.     

Alternate and random (co)polymers composed of anthracene and chloromethylstyrene units through controlled radical ring-opening polymerization: Synthesis,post-functionalization,and optical properties

A cyclic monomer containing the chloromethyl unit 10-methylene-9,10-dihydroanthryl-9-spiro(4′-chloromethylphenyl)cyclopropane (MDCMS) was polymerized using a controlled radical ring-opening polymerization via a reversible addition-fragmentation chain transfer (RAFT) process to afford a nonconjugated alternate polymer composed of anthracene and chloromethylstyrene (CMS) units. Well-defined random copolymers were obtained through the ring-opening RAFT copolymerization. Various functional groups were incorporated into the alternate polymer. The alternate polymer containing imidazole rings exhibited fluorescence quenching as a result of charge transfer. Fluorescence resonance energy transfer (FRET) was observed in the alternate polymers containing naphthalene and thiophene rings. The random copolymers obtained by copolymerization followed by post-functionalizations exhibited characteristic optoelectronic properties that differed from those of the alternate polymers.     

Side-Chain Metallocene-Containing Polymers by Living and Controlled Polymerizations

This review summarizes recent work on side-chain metallocene-containing polymers prepared by controlled and living polymerizations, which include living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). The majority of efforts in the field are focused on side-chain ferrocene-containing polymers, while cobaltocenium-containing polymers have recently started to draw attention. Future direction on the development of other metallocene-containing polymers is discussed.     

New polymerization of dienes and related monomers catalyzed by late transition metal complexes

This article reviews recent studies on the polymerization of 1,6-heptadienes and 2-aryl- and 2-alkoxy-1-methylenecyclopropanes catalyzed by Co, Fe, and Pd complexes. Co and Fe complexes with bis(imino)pyridine ligands catalyze the cyclopolymerization of 1,6-heptadiene in the presence of MMAO to produce the polymer, which contains five-membered rings in the monomer units. The polymers with cis- or trans-five-membered rings are obtained selectively, depending on the complex used in the polymerization. The catalyst, prepared from the Co complex having a bis(imino)pyridine ligand and MMAO, promotes the polymerization of 2-aryl-1-methylenecyclopropanes without ring-opening. The reaction under ethylene atmosphere produces alternating copolymer of the two monomers to yield the polymers composed of the C4 repeating unit with a 1,1-cyclopropanediyl group. The alternating copolymer of ethylene and 7-methylenebicyclo[4.1.0]heptane undergoes thermal rearrangement to afford the polymer with CC double bond in main chain. A radical pathway is proposed. Dinuclear π-allylpalladium complexes with bridging Cl ligands initiate living polymerization of 2-alkoxy-1-methylenecyclopropanes, which accompanies ring-opening of the monomer, to afford the polymers composed of the C₃ repeating units having alkoxy and vinylidene groups. A cyclic dinuclear π-allylpalladium complex reacts with 2-alkoxy-1-methylenecyclopropane in the presence of pyridine to produce the living polymer with macrocyclic structures. Block copolymerization of the two monomers that contain OR or O(CH₂CH₂O)R as the substituents on the three-membered ring, results in the polymers with hydrophobic and hydrophilic segments.     

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene: Synthesis, properties of the monomers and polybenzoxazines

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene (CP) cores have been synthesized. Theses monomers possessed controllable number of organic benzoxazine moieties and biphenyl groups distributed on the inorganic ring of CP. Corresponding ring-opening polymerization under heat led to highly cross-linked polymers with different number of crosslinking sites. The ring-opening polymerization behaviors of the new benzoxazine monomers were investigated by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). The results indicated that the polymerization activity of the monomers depended on the number of benzoxazine moiety of corresponding monomers. Those monomers with more benzoxazine moieties resulted in higher polymerization rate. Due to the high crosslinking nature with rigid and stable inorganic CP ring and biphenyl groups in the networks, the resulted polybenzoxazines from the monomers showed excellent thermal stability, mechanic property and humidity resistance.     

Reaktive Mikrogele,X. Anionische Polymerisation von 1,4-diisopropenylbenzol und 1,4-Divinylbenzol in verdünnter lösung

By anionic polymerization of 1,4-divinylbenzene reactive microgels were obtained having an unusual high amount of pending vinyl groups. With low initiator concentration weakly branched or even linear polymers were formed. The tendency of the second double bond to react during polymerization is still less in 1,4-diisopropenylbenzene, where essentially linear polymers could be isolated. The difference to radical emulsion polymerization of these monomers is emphasized and the unusual behaviour of tetrafunctional monomers in anionic polymerization is discussed.     

Activation in anionic polymerization: Why phosphazene bases are very exciting promoters

Recently, nitrogen-phosphorous hybrid organobases such as phosphazene bases (PBs), which possess a remarkably high basicity, have been extensively studied in organic synthesis. Their applications in the domain of anionic polymerization are reviewed. Those non-ionic superbases generate highly reactive anionic species according to two different pathways: firstly by deprotonation of weak acids in which the protonated phosphazene base forms the cation, and secondly by complexation of the lithium cation by the phosphazene base when organolithium compounds are used as initiators. They have been successfully used for the anionic ring-opening polymerization (AROP) of epoxides, cyclosiloxanes, cyclic esters, caprolactam, and very recently cyclopropane-1,1-dicarboxylates, as well as for the anionic polymerization of vinyl monomers such as methacrylates, acrylates, butadiene, and isoprene. Polymerizations with metal-free non-protonated phosphazenium counterions are also reviewed. In all cases, the rates of polymerization are much higher than those observed with metal cations, and similar to the values obtained with cryptated counterions. The use of protonated and non-protonated phosphazenium counterions leads generally to polymers with narrow molecular weight distributions, and well-controlled end groups. Advantages of PBs are discussed, and perspectives in the revisited domain of anionic activation applied to polymer chemistry are presented.     

Progress in the Preparation of Functional and (Bio)Degradable Polymers via Living Polymerizations

This review presents the latest developments in (bio)degradable approaches and functional aliphatic polyesters and polycarbonates prepared by typical ring-opening polymerization (ROP) of lactones and trimethylene carbonates. It also considers several recent innovative synthetic methods including radical ring-opening polymerization (RROP), atom transfer radical polyaddition (ATRPA), and simultaneous chain- and step-growth radical polymerization (SCSRP) that produce aliphatic polyesters. With regard to (bio)degradable approaches, we have summarized several representative cleavable linkages that make it possible to obtain cleavable polymers. In the section on functional aliphatic polyesters, we explore the syntheses of specific functional lactones, which can be performed by ring-opening copolymerization of typical lactone/lactide monomers. Last but not the least, in the recent innovative methods section, three interesting synthetic methodologies, RROP, ATRPA, and SCSRP are discussed in detail with regard to their reaction mechanisms and polymer functionalities.     

Radical addition-fragmentation chemistry in polymer synthesis

This review traces the development of addition-fragmentation chain transfer agents and related ring-opening monomers highlighting recent innovation in these areas. The major part of this review deals with reagents that give reversible addition-fragmentation chain transfer (RAFT). These reagents include dithioesters, trithiocarbonates, dithiocarbamates and xanthates. The RAFT process is a versatile method for conferring living characteristics on radical polymerizations providing unprecedented control over molecular weight, molecular weight distribution, composition and architecture. It is suitable for most monomers polymerizable by radical polymerization and is robust under a wide range of reaction conditions. It provides a route to functional polymers, cyclopolymers, gradient copolymers, block polymers and star polymers.     

Relationship between electron sensitivity and chemical structures of polymers as electron beam resists. VI: Electron sensitivity of various acetalized poly(vinyl alcohol)s

Acetalized poly(vinyl alcohol)s which were synthesized from poly(vinyl alcohol) (PVA) and aldehyde or ketone were evaluated as electron beam (EB) resists, in order to investigate the relationship between EB sensitivity and chemical structures of the polymers. It was found that the acetalized PVAs were easily crosslinked by EB exposure. The main mechanism of crosslinking may be radical reaction at acetal group. The sensitivity of the acetalized PVA depended on the structure of the acetal group. Acetalized PVAs synthesized from benzaldehyde, in which the electron attracting group was substituted on the benzene ring and from linear aliphatic aldehyde having a long alkyl chain, had high sensitivity. A high sensitivity of 7.2 × 10⁻⁷ C/cm² was attained when the acetalized PVA synthesized from p-chloro-benzaldehyde was used. Acetalized PVAs synthesized from PVA and aldehyde having a cyclic structure had an excellent dry etching durability and were suitable as negative EB resists.     

More insight into tandem ROMP and ADMET polymerization for yielding reactive long-chain highly branched polymers and their transformation to functional polymer nanoparticles

Tandem chain transfer ring-opening metathesis polymerization (ROMP-CT) and acyclic diene metathesis (ADMET) polymerization were carried out in a controlled one-pot procedure, and behaved noticeable differences in polymerization of monomers by different ruthenium catalysts, whereas there indeed had been two distinctly polymerization stages. In the first one, ROMP-CT of functional monomers was conducted in the presence of a symmetrical multi-olefin as chain transfer agent within various reaction time scales, yielding linear telechelic polymers. Next, ADMET polymerization of telechelic polymers was performed and generated a series of reactive long-chain highly branched polymers (LCHBPs) with acrylate and/or azobenzene groups having molecular weights of 8.5–47.9 kDa under varied conditions. LCHBPs were fully characterized by several techniques, and interestingly, UV–vis analysis displayed the specific peak at 278 nm, which offered a new evidence for the existence of internal acrylate structure on the LCHBP backbone, and supported the highly branched architecture of polymers. LCHBP containing a number of pendent acrylate groups was readily converted, by thiol-Michael addition click reaction, to novel thiol-functionalized intra-molecular crosslinked unimolecular polymer nanoparticles with diameter of 40–60 nm, which provided a facile method for post-functionalization of branched polymers.     

Synthesis of hyperbranched polymers via a facile self-condensing vinyl polymerization system - Glycidyl methacrylate/Cp2TiCl2/Zn

A facile self-condensing vinyl polymerization (SCVP) system, the combination of glycidyl methacrylate, Cp₂TiCl₂ and Zn, has been firstly used to prepare novel hyperbranched polymers, consisting of vinyl polymers as the backbone, and cyclic ester polymers (poly(?-caprolactone) or poly(l-lactide)) as the side chains. The polymerizations are initiated by the epoxide radical ring-opening catalyzed by Cp₂Ti(III)Cl which is generated in situ via the reaction of Cp₂TiCl₂ with Zn. The key to success is that the polymerizations can proceed concurrently via two dissimilar chemistries possessing the opposite active initiating species, including ring-opening polymerization (ROP) and controlled/living radical polymerization (CRP). We have demonstrated that this facile one-step polymerization technique can be applied successfully to prepare highly branched polymers with a multiplicity of end reactive functionalities including Ti alkoxide, hydroxyl and vinyl functional groups.     

自缩聚开环超支化聚合反应的动力学分析

通过严格的动力学方法推导出阴离子型自缩聚开环超支化共聚合体系(SCROCP)的分布函数及各级统计矩数,进而给出了该共聚体系的二维重量分布函数、数均、重均分子量及多分散指数的解析公式。在SCROCP中的研究成果可推广到阴离子型自缩聚开环均聚体系(SCROP)中,此时活化剂的当量少于单体的当量,有一些单体没有被活化剂激活成引发剂单体,反应体系实际上是按共聚的机理进行的。计算结果表明,当初始单体含量较高时,移除残余单体可以使体系的多分散指数大大降低。     

Borylated Polyolefins and their Applications

Different preparative routes for the attachment of organoboron moieties to polyolefins and applications of such materials are reviewed. Preparation from boron-functionalized monomers represents one possible synthetic strategy with free radical polymerization, Ziegler–Natta polymerization, and ring-opening metathesis polymerization methods as the most thoroughly studied procedures. Recent advances in the preparation of boron-containing polymers through polymer modification reactions provide an interesting alternative that allows for the facile preparation of well-defined organoboron polymers of various architectures including homo polymers, random copolymers, block copolymers, and telechelic polymers. New opportunities for organoboron polymers as supported catalysts, sensors, luminescent materials, device components, and precursors to ceramics are briefly discussed.     

Chemospecific ring-opening polymerization of α-methylenemacrolides

α-Methylenemacrolides having various groups, such as aromatic, ether, and amine, were enzymatically, anionically, and radically polymerized. The polymerization with the lipase catalyst successfully afforded polymers only through the ring-opening process, whereas the vinyl polymerizations selectively proceeded by using anionic and radical initiators. The polyesters obtained by the enzymatic polymerization have a polymerizable methacrylic methylene group in the main-chain, in addition to the aromatic and polar groups, and were further radically polymerized to quantitatively produce a cross-linked polymer gel.     

液体橡胶的制备方法

液体橡胶作为低分子功能性聚合物,在塑料加工等领域具有广阔的应用前景。介绍了单体聚合和橡胶降解制备液体橡胶的方法,单体聚合法包括自由基乳液聚合、自由基溶液聚合、负离子聚合、正离子聚合等,橡胶降解法主要包括氧化降解、光催化降解、微生物降解等,提出液体橡胶的研究方向为探索新的合成技术及聚合体系,降低生产成本,改进后处理工艺,充分回收溶剂,走绿色环保加工之路。     

Rheological and chemorheological studies of cyclic aryl ether ketone and aryl ether thioether ketone oligomers containing the 1,2-dibenzoylbenzene moiety

The melt stability, shear rate, and temperature dependence of steady-state shear viscosity of molten cyclic aryl ether ketone and thioether ketone oligomers containing the 1,2-dibenzoylbenzene moiety have been investigated. The isothermal chemorheology of the ring-opening polymerization of cyclic oligomers 4 and 9 in the presence of a nucleophilic initiator was also conducted. The cyclic aryl ether ketone oligomers are thermally stable in the melt, and their melt viscosity is several orders of magnitude lower than their high molecular weight linear counterparts. At a given temperature, the steady-state shear viscosity of the molten cyclics initially undergoes shear thinning as the shear rate increases, and once the shear rate is above 10 s⁻¹, the molten cyclic oligomers behave like Newtonian fluids. For the amorphous cyclic oligomers studied, the steady-state shear viscosity at 100 s⁻¹ at a given temperature only depends on their glass transition temperature. The cyclic aryl thioether ketone oligomers are thermally unstable in the melt and undergo ring-opening polymerization in the absence of an initiator to form high molecular weight linear polymers with a concomitant rapid increase in viscosity. The rate of change in viscosity increases with temperature and is promoted by the addition of a catalytic amount of elemental sulfur or a disulfide such as 2,2-dithiobis(benzothiazole). It is hypothesized that the ring-opening polymerization is initiated by the in situ generated thiyl radical(s) and proceeds via a free radical route. © 1996 John Wiley & Sons, Inc.