Depolymerization of fluoroalkyl methacrylate polymers as studied with thermogravimetry

Thermal behaviors of a few kinds of poly(fluoroalkyl methacrylate) prepared by γ-or UV-ray polymerization were investigated by using thermogravimetric measurements with the intermittent analysis of the gaseous products. The degradation of fluoroalkyl methacrylate polymers, monomeric units of which were CH₂=C(CH₃)COOCH₂(CF₂CF₂)_nH, n = 1, 2, and 3, proceeded according to the depolymerization mechanism reproducing the pristine monomer exclusively, but the thermogram in inert atmosphere showed the features of a two-step reaction. Two species of polymer differing in the heat stability were supposed to exist in the polymeric substance produced by γ- or UV-ray irradiation, and the fraction of polymer having lower heat stability increased with the increasing length of the fluoroalkyl ester group. In air, however, the thermogram of poly(fluoroalkyl methacrylate) showed no such a stepwise weight decrease as was observed in inert atomsphere with the elevating temperature, and the temperatures at which the depolymerization was introduced shifted to a much higher region. The results were ascribed to the reaction of initiating polymer radicals produced on polymer having lower stability with oxygen to form hydroperoxide, which once stabilized the polymer radicals and obstructed the initiaition of the unzipping reaction till higher temperature.     

Poly(methylphenylphosphazene)–Graft–Poly(methyl Methacrylate) Copolymers Via Atom Transfer Radical Polymerization

Atom transfer radical polymerization (ATRP) was used to graft poly(methyl methacrylate), PMMA, onto poly(methylphenylphosphazene), [(Me)(Ph)PN] _n , PMPP. A two-step process was used to convert a portion of the methyl substituents on [(Me)(Ph)PN] _n to –CH₂C(CH₃)₂OH groups and then to bromoalkyl groups, –CH₂C(CH₃)₂OC(=O)C(CH₃)₂Br, the latter of which served as initiation sites for ATRP of methyl methacrylate (MMA) in the presence of CuCl/bipyridine. Variations in the length of the grafted chains were investigated and the graft copolymers were compared to the parent polymer and blends of similar composition. The new bromoalkyl derivatives of [(Me)(Ph)PN] _n and the PMPP–graft–PMMA copolymers were characterized by elemental analysis, ¹H and ³¹P NMR spectroscopy, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC). We dedicate this paper to Professor Harry R. Allcock for consistently maintaining the highest standards in his creative, pioneering work in inorganic rings and polymers.     

Effect of the length of branches on the critical surface tension of poly(n-alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile

Critical surface tension values γ_c were measured for poly(n-alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile. Surface tension values γ_L of n-alkyl methacrylate increase with increasing side chain length: γ_L = 23.2 dynes/cm for methyl methacrylate to 33.2 dynes/cm for stearyl methacrylate, but γ_c values of poly(n-alkyl methacrylate) decrease with increasing side chain length: γ_c = 36.3 dynes/cm for poly(methyl methacrylate) to 20.8 dynes/cm for poly(stearyl methacrylate). The decrease in γ_c is attributed to a tighter packing of the alkyl chain with a greater concentration of the pendent ? CH₃ group at the air/solid interface. Values of γ_c of copolymers hardly depended on the methacrylonitrile content in copolymers and did not satisfy the equation γ_c = N₁γ_c1 + N₂γ_c2 proposed by Lee. The difference in γ_c values for casting, annealing, and quenching films of poly(stearyl methacrylate) and the surface structure of copolymers were discussed using electron microscopy and measurement of melting point, heat of melting, and γ_c.     

P[CF3(CF2)5CH2MA‐co‐MMA] and P[CF3(CF2)5CH2MA‐co‐BA] copolymers: Reactivity ratios and surface properties

This study aimed at reducing the surface energy of coatings by copolymerization of commonly used monomers with fluorine‐containing monomers. Copolymers of 1,1‐dihydroperfluoroheptyl methacrylate (FHMA) and methyl methacrylate (MMA) or butyl acrylate (BA) are prepared by low‐conversion polymerization in solution. Using ¹H‐NMR data and nonlinear least‐squares data fitting, reactivity ratios of these systems at 80°C are determined to be r_FHMA = 1.31, r_MMA = 0.76, and r_FHMA = 3.15, r_BA = 0.38, respectively. We assume that the penultimate unit effect plays an important role in these systems. Introduction of the perfluoroalkyl side chain lowers the polymer surface energy significantly; copolymers of MMA and FHMA show a reduction in total surface energy of about 50 % at a content of 15 mol % FHMA as compared with pure PMMA. The attainable reduction in surface energy is much larger than with, for example, Teflon. This is due to the preferential adsorption of the —CF₃ groups of the fluoroalkyl side chain, if compared to that of the —CF₂— groups of Teflon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 159–165, 2001     

Reactions of copper ions with amines in the presence of self‐assembled fluorinated oligomeric aggregates

Copper acetylacetonate reacted with N,N‐diethylmethylamine and 4,4′‐thiobis(6‐t‐butyl‐o‐cresol) in the presence of self‐assembled fluorinated oligmeric aggregates formed by fluoroalkyl end‐capped 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate–N,N‐dimethylacrylamide cooligomer [R_F–(BTRI)_x–(DMAA)_y–R_F; R_F = CF(CF₃)OCF₂CF(CF₃)OC₃F₇] to afford stable fluorinated aggregates–copper ions nanocomposites. These fluorinated oligomeric aggregates–copper ions nanocomposites thus obtained were applied to the dispersion of copper ions nanocomposites above the traditional organic polymeric materials such as poly(methyl methacrylate) (PMMA) surface. On the other hand, copper (II) chloride reacted with hydrazine hydrate in the presence of fluorinated oligomeric aggregates formed by fluoroalkyl end‐capped N,N‐dimethylacrylamide homooligomer to afford stable copper nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1328–1334, 2006     

Surface properties for poly(perfluoroalkylethyl methacrylate)/poly(n-alkyl methacrylate)s mixtures

A poly(perfluoroalkylethyl methacrylate) and a series of poly(n-alkyl methacrylate)s such as poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n-butyl methacrylate) were prepared and used to investigate the surface properties of polymer mixtures containing a fluorinated homopolymer and a nonfluorinated homopolymer and the effect of the side-chain length of poly(n-alkyl methacrylate) on the surface free energy for the polymer mixtures. Contact angles were measured for the surfaces of polymer mixtures by varying the concentration of poly(perfluoroalkylethyl methacrylate). From the contact angle data, it can be inferred that most of the poly(perfluoroalkylethyl methacrylate) added to poly(n-alkyl methacrylate)s is located in the outermost layer of polymer-mixture surface. Surface free energies for the outermost surfaces of polymer mixtures were calculated from the contact angle data using Owen and Wendt's equation. The decrease in the surface free energy for the polymer mixture with the poly(perfluoroalkylethyl methacrylate) addition is more pronounced as the side-chain length of poly(n-alkyl methacrylate) decreases. Due to the steric effect of the side chain of poly(n-alkyl methacrylate), the arrangement of the perfluoroalkylethyl group of poly(perfluoroalkylethyl methacrylate) to the air side is considerably hindered. The ESCA analysis of atomic compositions of the surface for the polymer mixture verified that poly(perfluoroalkylethyl methacrylate) is preferentially arranged and concentrates at the polymer mixture–air interface. The results of functional group compositions obtained by ESCA showed that the functional group composition of  CF₃ for the outermost layer has a more important effect on the surface free energy than that of  CF₂ and confirmed the hindrance of the arrangement of perfluoroalkylethyl group to the air side by the side chain of poly(n-alkyl methacrylate). © 1994 John Wiley & Sons, Inc.     

New AB or ABA type block copolymers: atom transfer radical polymerization (ATRP) of methyl methacrylate using iodine-terminated PVDFs as (macro)initiators

Summary PMMA homopolymer with CF₃(CF₂)₂CF₂- end group was prepared by the ATRP of MMA using CF₃(CF₂)₂CF₂-I as an initiator and copper(I) salts/bipy catalysts. This indicated the production of perfluorobutyl radicals by ATRP mechanism and successful polymerization by them. Di- and triblock copolymers were also prepared by the ATRP of MMA using iodine-terminated PVDF as (macro)initiators. The kinetic plots (ln[M]_o/[M] vs. time) showed nearly first-order with respect to monomer concentration and the M_n,NMR of block copolymers increased linearly with conversion. However, iodine-terminated PVDF showed low initiator efficiency because propagating rate was much faster than initiating rate Received: 6 September 1999/Revised version: 27 December 1999/Accepted: 28 December 1999     

Thermal behavior of novel hybrid inorganic-organic phosphazene polymers

The thermal behavior of the following systems have been investigated by TGA and XPS: the homopolymer of N:P:Cl₄(CH₂)(CH₂C₆H₄CH–CH₂) (1). copolymers of1 with MMA and styrene, and copolymers of N:P:Cl₄(1-C₃II) [C[OC(O)CH₃]–CH₃] (2) with MMA and styrene. Upon heating under TGA conditions the highest char yield (64wt⁰ ₀) is found for the homopolymer of1. The char yields for the copolymers appear to increase with increasing amounts of phosphazene incorporated. The one-step weight loss observed for the homopolymer of1 can be ascribed mainly to climination of HCl. The1 styrene copolymers decompose in one step, indicating that HCl elimination, ring degradation, and depolymerization take place simultaneously. The1 MMA copolymers show a two-step degradation. From XPS scans it follows that complete loss of chlorine takes place in the first step and probably in combination with some depolymerization of MMA units. In the second step phosphazene ring degradation is observed, accompanied by further carbonization of the sample. The2 styrene copolymers start to decompose about 100 C lowe than the1 MMA copolymers, also exhibiting a two-step TGA curve. The first step can be associated with breakdown of polymer chains at the C–C linkage between inorganic monomers. In the second step depolymerization of the styrene sequences. HCl elimination, and ring degradation occur.     

Nickel(II) complexes bearing the bis(β‐ketoamino) ligand for the copolymerization of norbornene with a higher 1‐alkene

A novel bis(β‐ketoamino)Ni(II) complex catalyst, Ni{CF₃C(O)CHC[N(naphthyl)]CH₃}₂, was synthesized, and the structure was solved by a single‐crystal X‐ray refraction technique. The copolymerization of norbornene with higher 1‐alkene was carried out in toluene with catalytic systems based on nickel(II) complexes, Ni{RC(O)CHC[N(naphthyl)]CH₃}₂(R?CH₃, CF₃) and B(C₆F₅)₃, and high activity was exhibited by both catalytic systems. The effects of the catalyst structure and comonomer feed content on the polymerization activity and the incorporation rates were investigated. The reactivity ratios were determined to be r_1‐octene = 0.009 and r_norbornene = 13.461 by the Kelen–Tüdõs method for the Ni{CH₃C(O)CHC[N(naphthyl)]CH₃}₂/B(C₆F₅)₃ system. The achieved copolymers were confirmed to be vinyl‐addition copolymers through the analysis of ¹H‐NMR and ¹³C‐NMR. The thermogravimetric analysis results showed that the copolymers exhibited good thermal stability (decomposition temperature, T_dec > 400°C), and the glass‐transition temperature of the copolymers were observed between 215 and 275°C. The copolymers were confirmed to be noncrystalline by wide‐angle X‐ray diffraction analysis and showed good solubility in common organic solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of polyphosphazene random copolymers bearing alkoxyethoxy and trifluoroethoxy functional groups

The anionically initiated copolymerization of (CH₃OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃, and (CH₃OCH₂CH₂OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃ with (CF₃CH₂O)₃ P=N-Si(CH₃)₃ is reported. These materials were characterized by³¹P and¹H NMR, SEC, and DSC.In situ ³¹P NMR studies indicate that monomers are simultaneously consumed, SEC traces show that these random copolymers exhibit monomodal distributions, and there is a gradient in solubilities as well as thermal and mechanical properties which is dependent upon the repeating unit ratios.     

Synthesis of fluoroalkyl‐modified polyester and its application in improving the hydrophobicity and oleophobicity of cured polyester coatings

The fluoroalkyl‐modified polyester (PE‐F_n) was synthesized by the reaction of polyester resin (PE) and fluorinated isocyanate, and the structure of the synthesized product was characterized by proton nuclear magnetic resonance (¹H‐NMR) and fluorine nuclear magnetic resonance (¹⁹F‐NMR). The water and oil wettability of the cured PE coatings with PE‐F_n as additives was investigated by contact angle meter. The results showed that the introduction of an extremely low concentration of PE‐F_n into PE led to the increase in contact angle of water and diiodomethane on cured PE coatings, and the decrease in the surface free energy. The X‐ray photoelectron spectroscopic (XPS) analysis showed that the F/C molar ratio in the outer few nanometers was significantly higher than that in the bulk, indicating that the fluoroalkyl groups in PE‐F_n had enriched on the coating surface. It was also found that longer fluoroalkyl groups and fluoroalkyl groups with ? CF₃ at its end had the higher tendency to aggregate on the coating surface. The topological structures of the cured coatings were recorded by an atomic force microscope under tapping mode and the results revealed that there was a strong surface segregation of fluorinated species. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39812.     

Amphiphilic Copolymers PDMAEMAm-b-PAAn and Their Complexes with Surfactants at the Air/Water Interface

The properties of amphiphilic copolymers (poly(2-(dimethylamino)ethyl methacrylate)-block-poly(acrylic acid), PDMAEMA_m-b-PAA_n) and their complexes with a traditional surfactant (dimethyldioctadecylammonium bromide) and a novel Gemini surfactant, (propanediyl-bis(dimethyloctadecylammonium bromide) ([C₁₈H₃₇(CH₃)₂N⁺-(CH₂)₃-N⁺(CH₃)₂ C₁₈H₃₇]·2Br⁻, 18-3-18), at the air/water interface were investigated. Surface tension and surface pressure were used to monitor the surface behavior of these systems, and atomic force microscopy was used to visualize the morphology of the corresponding Langmuir–Blodgett film. PDMAEMA_m-b-PAA_n can form surface micelles at the air/water interface and the addition of surfactants can significantly influence the structure of the complex film due to electrostatic interaction and hydrophobic interaction. In particular, the spacer in a Gemini surfactant can act as a bridge to connect different PDMAEMA₇₀-b-PAA₆₀ micelles, which is favorable for the formation of a necklace-like structure. This originates from that one head group can interact with a PDMAEMA₇₀-b-PAA₆₀ molecule, and the other head group can interact with another PDMAEMA₇₀-b-PAA₆₀ molecule, which might belong to different micelles. The results suggest that the special interfacial structures and performances of Gemini/PDMAEMA-b-PAA complexes are caused by the unique molecular structures of the Gemini surfactant.     

Polymerization of Cyclophosphazenes with Spriocyclic Methacrylate Containing Substituents

The radical addition polymerization and copolymerization of the cyclophosphazene monomers with spirocyclic methacrylate containing substituents, spiro(2,3-dioxypropylmethacryloyl)tetrachlorocyclotriphosphazene, N₃P₃Cl₄[OCH₂CH(OC(O)=CH₂)O] (1) and spiro((2-methyl-3-oxy-2-(oxymethyl)propyl)methacryloyl)tetrachlorocyclotriphosphazene, N₃P₃Cl₄[OCH₂CMe(CH₂OC(O)=CH₂)CH₂O] (2), has been investigated. In the case of 1, homopolymerization using AIBN as the initiator yielded only cross-linked solids. Copolymerization of 1 with methyl methacrylate was accomplished using VAZO 52 under milder initiation temperature. GPC of copolymer suggested a significant amount of chain transfer. Homopolymerization of 2 gave low isolated yields of the homopolymer but copolymerization with methyl methacrylate yielded the expected copolymers. The reactive chlorine atoms in the copolymers of 2 can be replaced by trifluoroethoxide or methyl amine. Thermal properties of the copolymers were examined by DSC, TGA and pyrolysis mass spectrometry.     

Copolymerization of norbornene and <Emphasis Type="Italic">n</Emphasis>-butyl methacrylate catalyzed by bis-(β-ketoamino)nickel(II)/B(C<Subscript>6</Subscript>F<Subscript>5</Subscript>)<Subscript>3</Subscript> catalytic system

Abstract  

Copolymerization of norbornene with n-butyl methacrylate (n-BMA) was carried out with catalytic systems of bis-(β-ketoamino)nickel(II) complexes Ni{RC(O)CHC[N(naphthyl)]CH₃}₂ (R = CH₃, CF₃) and B(C₆F₅)₃ in toluene and exhibited high activity for both catalytic systems. Influence of the catalyst structure and comonomer feed content on the polymerization activity as well as on the incorporation rates were investigated. The catalysis was proposed to involve the insertion mechanism of norbornene and n-BMA catalyzed by bis-(β-ketoamino)nickel(II)/B(C₆F₅)₃ catalytic systems, and the decreasing polymerization activity with an increasing content of n-BMA in the feedstock composition could be attributed to the competition of carbonyl group coordination onto the Ni(II) active center instead of the olefin double bond. The reactivity ratios were determined to be r _n-BMA = 0.095 and r _norbornene = 12.626 by the Kelen–Tüd?s method. The copolymer films prepared show good transparency in the visible region.     

Synthesis of terpolymers having a phospholipid polar group and poly(oxyethylene) in the side chain and their protein adsorption–resistance properties

Terpolymers having phospholipid polar groups were synthesized from 2‐methacryloyloxyethyl phosphorylcholine (MPC), methacryloyl or acryloyl poly(oxyethylene) macromonomers (POEM) [(CH₂CH₂O)_n (where n = 2–23); PEOM(2), PEOM(23), ME(9), Ph(6)], and n‐butyl methacrylate (BMA). The characteristics of these terpolymer membranes were investigated by water content (H) and X‐ray photoelectron spectroscopy. The content of water in the terpolymer increased with increasing content of MPC and length of oxyethylene units. The membranes of terpolymers were found to adsorb bovine serum albumin much less than those of poly(methyl methacrylate) and poly(BMA). Even though the contents of MPC in the terpolymer were 5 to 25 mol %, the terpolymer depressed BSA adsorption more than poly(MPC‐co‐BMA) consisting of 29 mol % of MPC. The use of terpolymer with POEM can decrease the amount of MPC in the polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1092–1105, 2002     

Homopolymer of 4-chloro-3-methyl Phenyl Methacrylate and its Copolymers with Butyl Methacrylate: Synthesis, Characterization, Reactivity Ratios and Antimicrobial Activity

The methacrylate monomer 4-chloro-3‐methyl phenyl methacrylate (CMPM) was synthesized by reacting 4-chloro-3‐methyl phenol with methacryloyl chloride. The homopolymer and various copolymers of CMPM with n-butyl methacrylate were synthesized by free-radical polymerization in toluene at 70°C using 2,2′-azobis(isobutyronitrile) as the initiator. The CMPM monomer was characterized by Fourier transform IR and ¹H-NMR studies. The copolymers were characterized by IR spectroscopy. The molecular weights (M _n and M _w) and the polydispersity index were obtained from gel permeation chromatography. The solubility and intrinsic viscosity of the homopolymer and the copolymers are also discussed here. The copolymer composition obtained from UV spectra led to the determination of reactivity ratios employing Fineman-Ross and Kelen-Tudos linearization methods. Thermogravimetric analyses of the homopolymer and the copolymers were carried out under a nitrogen atmosphere. The homopolymer and the copolymers prepared were tested for their antimicrobial activity against bacteria, fungi and yeasts.     

New fluorine-containing polyorganosilsesquioxanes: Preparation and properties

It has been found that hydrolysis of three-functional alkoxysilanes, such as R^FOCH₂Si(OR^F)₃, R^F = CH₂CF₃, CH₂CF₂CF₃, CH₂CF₂CF₂CF₃, and CH₂CF₂CF₂CF₂CF₃, under mild conditions upon exposure to air moisture in the presence of ??-aminopropyltriethoxysilane results in the formation of hydrophobic coatings from fluorine-containing polyorganosilsesquioxanes directly on the substrate. Polymers have a layered ladder structure. The hydrophobicity and low values of refractive indices, surface energy, and its polar component, as well as the simplicity of the preparation, determine the possibility of using polyorganosilsesquioxane films as antireflection protective coatings for laser optics.     

Thermal analysis and characterization of 2-allylphenoxyorganocyclotriphosphazene copolymers

The radical copolymerizations of I (2-allylphenoxyorganocyclotriphosphazene) with chloride, phenoxy, 2,2,2-trifluoroethoxy side group reacting with II (styrene, methyl methacrylate and vinylbenzyl chloride) using AIBN, n-BuLi and ultraviolet as initiator were investigated. The type of the copolymerization, reaction time, temperature were evaluated to obtain the optimum reaction condition. The incorporation of organophosphazene units into an organic polymer backbone decreased the glass transition temperature and increased the thermal stability of the copolymers. The weight conversion and the molecular weight had a maximum value at reaction temperature of around 70 °C. The order for both weight conversion of the copolymerization and the thermal stability of phosphazene polymer with the co-monomer was VBC > STY > MMA, and with the side group Cl-> C₆H₅O-> CF₃CH₂O-. The phosphazene copolymer is of conductivity and crystallization.     

Plasma polymerization of perfluoro-2-butyltetrahydrofuran/methane and perfluorobezene/tetrafluoromethane mixtures and gas permeation properties of the plasma polymers

Plasma polymer films prepared from perfluoro-2-butyltetrahydrofuran (PFBTHF) and perfluorobenzene (PFB) were investigated by elemental analysis, infrared spectroscopy, and ESCA. The gas separation properties were also investigated to seek plasma polymer films with good permselectivity. Plasma polymer films from PFBTHF and PFB were composed of polymer chains with fluorinated moieties such as C –CF_n, C F, C F–CF_n, C F₂, and C F₃ groups. Changes in the afcurrent as an operating condition for plasma polymerization showed less influence on the distribution of the fluorinated moieties but more influence on the permselectivity of the plasma polymer films formed. The permselectivity was improved by plasma polymerization in the PFBTHF/CH₄ or PFB/CF₄ mixture systems. The P_O2/P_N2 ratio for the plasma polymer films prepared from PFBTHF/CH₄ and PFB/CF₄ mixtures increased from 3.1 at 0 mol % CH₄ to 4.0 at 50 mol % CH₄ addition, and from 4.1 at 0 mol % CF₄ to 5.0 at 25 mol % CF₄ addition, respectively. The permselectivity of the plasma polymer films may be related to the crosslinkage and aggregation of polymer chains rather than the elemental composition.     

Neutral Pd(II) and Ni(II) Acetylide Catalysts for the Polymerization of Methyl Methacrylate

Homogenous polymerization of methyl methacrylate using Pd(II)- and Ni(II)-based acetylide complexes as initiators has been investigated. M(PR'₃)₂(CCR)₂ (M=Pd, Ni; R'=PPh₃, Pn-Bu₃; R=Ph, CH₂OH, CH₂OOCCH₃, CH₂OOCPh, CH₂OOCPhOH-o) were found to be a novel type of effective initiators for the polymerization of methyl methacrylate. Among them, Pd(C CPh)₂(PPh₃)₂ (PPP) shows the highest activity in the MMA polymerization and the PMMA obtained is a syndiotactic polymer with high number-average molecular weight (M _n) of 14.1 × 10⁴. Some features and kinetic behavior of MMA polymerization initiated by PPP were studied in detail. The polymerization reaction is first-order with respect to both [PPP] and [MMA]. Radical polymerization mechanism is proposed.