Macrocyclization of polymers via ring‐closing metathesis and azide/alkyne‐“click”‐reactions: An approach to cyclic polyisobutylenes

The end‐to‐end cyclization of telechelic polyisobutylenes (PIB's) toward cyclic polyisobutylenes is reported, using either ring‐closing metathesis (RCM) or the azide/alkyne‐“click”‐reaction. The first approach uses bisallyl‐telchelic PIB's (M_n = 1650, 3680, 9770 g mol^?1) and Grubbs 1st‐, 2nd‐, and 3rd‐generation catalyst leading to cyclic PIB's in 60–80% yield, with narrow polydispersities (M_w/M_n = 1.25). Azide/alkyne‐“click”‐reactions of bisalkyne‐telechelic PIB's (M_n = 3840 and 9820 g mol^?1) with excess of 1,11‐diazido‐undecane leads to the formation of mixtures of linear/cyclic PIB's under formation of oligomeric cycles. Subsequent reaction of the residual azide‐moieties in the linear PIB's with excess of alkyne‐telechelic PEO enables the chromatographic removal of the resulting linear PEO‐PIB‐block copolymers by column chromatography. Thus pure cyclic PIB's can be obtained using this double‐“click”‐method, devoid of linear contaminants. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 671–680, 2010     

Asymmetric,regio‐ and stereo‐selective alternating copolymerization of CO2 and propylene oxide catalyzed by chiral chromium Salan complexes

Chiral chromium complexes of tetradentate N,N′‐disubstituted bis(aminophenoxide) (designated as Salan, a saturated version of Schiff‐base Salen ligand) in conjunction with an ionic quaternary ammonium salt can efficiently catalyze the copolymerization of CO₂ with racemic propylene oxide (rac‐PO) at mild conditions to selectively afford completely alternating poly(propylene carbonate) (PPC) with ～ 95% head‐to‐tail linkages and moderate enantioselectivity. These new catalyst systems predominantly exceed the previously much‐studied SalenCr(III) systems in catalytic activity, polymer enantioselectivity, and stereochemistry control. The chiral diamine backbone, sterically hindered substitute groups on the aromatic rings, and the presence of sp³‐hydridized amino donors and its N,N′‐disubstituted groups in chiral SalanCr(III) complexes all play significant roles in controlling polymer stereochemistry and enantioselectivity. Furthermore, a relationship between polycarbonate enantioselectivity and its head‐to‐tail linkages in relation to regioselective ring‐opening of the epoxide was also discussed on the basis of stereochemical studies of PPCs derived from the copolymerization of CO₂ with chiral PO at various conditions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6102–6113, 2008     

A one‐step strategy for aliphatic poly(carbonate‐ester)s with high performance derived from CO2, propylene oxide and l‐lactide

To improve the performance of PPC, aliphatic poly(carbonate‐ester)s were prepared in one‐step strategy from the terpolymerization of CO₂, propylene oxide (PO), and l ‐lactide (L ‐LA) catalyzed by zinc glutarate. Consequently giving high‐molecular weight terpolymers (PPCLAs) in a very high yield (8450.8–9435.8 g mol^?1 of Zn). The resulting terpolymers PPCLAs were characterized by ¹H NMR, showing that PPCLAs had an almost alternating structure for the components of CO₂, PO, and L‐LA. The influence of molecular weight and L‐LA content on the properties of PPCLAs was also investigated. Differential scanning calorimetry and thermogravimetric analysis (measurements revealed that the glass transition temperature (T _g) and thermal decomposition temperature (T _d) of PPCLAs are all much higher than those of PPC and increased with increasing molecular weight and L‐LA content. Tensile tests showed that the high mechanical properties of PPCLAs are due to the introduction of L‐LA into the copolymerization of CO₂ and PO. Furthermore, PPCLA4 exhibits high degradability, and after 10 weeks, the weight loss increases up to 6.58%, which is significantly higher than that of PPC of 4.58%. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation of poly(propylene‐co‐γ‐butyrolactone carbonate) and release profiles of drug‐loaded microcapsules

A new aliphatic poly(propylene‐co‐γ‐butyrolactone carbonate) (PPCG) was successfully synthesized through the copolymerization of carbon dioxide, propylene oxide (PO), and γ‐butyrolactone (GBL). GBL was inserted into the backbone of PO–CO₂. The glass transition of PPCG was as high as 16 °C, far higher than that (?1.5 °C) of poly(propylene carbonate) (PPC). The decomposition temperatures of PPCG and PPC were only slightly different. Because of the existence of the GBL ester unit, PPCG had stronger degradability than PPC in a pH 7.4 phosphate‐buffered solution. However, when the PO/GBL ratio increased beyond 5:2, the excessive amount of GBL was not added to the polymerization. PPCG and PPC microcapsules were prepared by the water‐in‐oil‐in‐water multiple‐emulsion method. Glucose was encapsulated. The PPCG microcapsules, about 2 μm in diameter, had smooth and spherical surfaces. The glucose release test revealed that the glucose release speed of the PPCG–glucose microcapsules was more than eight times faster than that of the PPC–glucose microcapsules in a pH 7.4 phosphate‐buffered solution. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2468–2475, 2005     

Copolymerization of propylene with 1,3‐butadiene using isospecific zirconocene catalysts

Poly(propylene‐ran‐1,3‐butadiene) was synthesized using isospecific zirconocene catalysts and converted to telechelic isotactic polypropylene by metathesis degradation with ethylene. The copolymers obtained with isospecific C₂‐symmetric zirconocene catalysts activated with modified methylaluminoxane (MMAO) had 1,4‐inserted butadiene units ( 1,4‐BD ) and 1,2‐inserted units ( 1,2‐BD ) in the isotactic polypropylene chain. The selectivity of butadiene towards 1,4‐BD incorporation was high up to 95% using rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride (Cat‐A)/MMAO. The molar ratio of propylene to butadiene in the feed regulated the number‐average molecular weight (M_n) and the butadiene contents of the polymer produced. Metathesis degradations of the copolymer with ethylene were conducted with a WCI₆/SnMe₄/propyl acetate catalyst system. The ¹H NMR spectra before and after the degradation indicated that the polymers degraded by ethylene had vinyl groups at both chain ends in high selectivity. The analysis of the chain scission products clarified the chain end structures of the poly(propylene‐ran‐1,3‐butadiene). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5731–5740, 2007     

Regio‐regular structure high molecular weight poly(propylene carbonate) by rare earth ternary catalyst and Lewis base cocatalyst

Lewis base modification strategy on rare earth ternary catalyst was disclosed to enhance nucleophilic ability of active center during copolymerization of carbon dioxide and propylene oxide (PO), poly(propylene carbonate) (PPC) with H‐T linkages over 83%, and number–average molecular weight (M_n) up to 100 kg/mol was synthesized at room temperature using Y(CCl₃OO)₃‐ZnEt₂‐glycerine catalyst and 1,10‐phenanthroline (PHEN) cocatalyst. Coordination of PHEN with active Zinc center enhanced the nucleophilic ability of the metal carbonate, which became more regio‐specific in attacking carbon in PO, leading to PPC with improved H‐T linkages. Moreover, the binding of PHEN to active Zinc center also raised the carbonate content of PPC to over 99%, whereas the PPC from common rare earth ternary catalyst was about 96%. Unlike the highly regio‐regular structure PPC but with relatively low molecular weight recently reported in the literature, our high molecular weight regio‐regular PPC did show significant improvement in thermal and mechanical performances. PPC with H‐T linkages up to 83.2% showed glass transition temperature (T_g) of 43.3 °C, while T_g of PPC with H‐T linkages of 69.7% was only 36.1 °C. When H‐T connectivity was raised from 69.7 to 83.2%, the modulus of PPC showed a 78% increase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4451–4458, 2008     

Living/controlled cationic cyclopolymerization of divinyl ether with a cyclic acetal moiety: Synthesis of poly(vinyl ether)s with high glass transition temperature based on incorporation of cyclized main chain and cyclic side chains

Cationic cyclopolymerization of 2‐methyl‐5,5‐bis(vinyloxymethyl)‐1,3‐dioxane ( 1 ), a divinyl ether with a cyclic acetal group, was investigated with the HCl/ZnCl₂ initiating system in toluene and methylene chloride at ?30 °C. The reaction proceeded quantitatively to give gel‐free, soluble polymers in organic solvents. The number‐average molecular weight (M_n) of the polymers increased in direct proportion to monomer conversion, and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that the polymerization proceeded in living/controlled manner. The contents of the unreacted vinyl groups in the produced soluble polymers were less than ～3 mol %, and therefore, the degree of cyclization was determined to be ～97%. In contrast, the pendant cyclic acetal groups remained intact in the polymers under the present cationic polymerization conditions. These facts show that cyclopolymerization of 1 almost exclusively occurred and the poly(vinyl ether)s with the cyclized repeating units and cyclic pendant acetal rings were obtained. Glass transition temperature (T_g) and thermal decomposition temperature (T_d) of poly( 1 ) (M_n = 7870, M_w/M_n = 1.57) were found to be 166 and 338 °C, respectively, indicating that poly( 1 ) had high T_g and high thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 952–958, 2010     

Crosslinkable poly(propylene carbonate): High‐yield synthesis and performance improvement

A crosslinking strategy was used to improve the thermal and mechanical performance of poly(propylene carbonate) (PPC): PPC bearing a small moiety of pendant C?C groups was synthesized by the terpolymerization of allyl glycidyl ether (AGE), propylene oxide (PO), and carbon dioxide (CO₂). Almost no yield loss was found in comparison with that of the PO and CO₂ copolymer when the concentration of AGE units in the terpolymer was less than 5 mol %. Once subjected to UV‐radiation crosslinking, the crosslinked PPC film showed an elastic modulus 1 order of magnitude higher than that of the uncrosslinked one. Moreover, crosslinked PPC showed hot‐set elongation at 65 °C of 17.2% and permanent deformation approaching 0, whereas they were 35.3 and 17.2% for uncrosslinked PPC, respectively. Therefore, the PPC application window was enlarged to a higher temperature zone by the crosslinking strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5329–5336, 2006     

Preparation of amphiphilic poly(ethylene oxide)‐block‐polystyrene macrocycles via glaser coupling reaction under CuBr/pyridine system

The amphiphilic cyclic poly(ethylene oxide)‐block‐polystyrene [c‐(PEO‐b‐PS)] was synthesized by cyclization of propargyl‐telechelic poly(ethylene oxide)‐block‐polystyrene‐block‐poly(ethylene oxide) (?? PEO‐b‐PS‐b‐PEO? ?) via the Glaser coupling. The hydroxyl‐telechelic ABA triblock PEO‐b‐PS‐b‐PEO was first prepared by successive living anionic polymerization of styrene and ring‐opening polymerization of ethylene oxide, and then the hydroxyl ends were reacted with propargyl bromide to obtain linear precursors with propargyl terminals. Finally, the intramolecular cyclization was conducted in pyridine under high dilution by Glaser coupling of propargyl ends in the presence of CuBr under ambient temperature, and the c‐(PEO‐b‐PS) was directly obtained by precipitation in petroleum ether with high efficiency. The cyclic products and their corresponding linear precursor ?? PEO‐b‐PS‐b‐PEO? ? were characterized by means of GPC, ¹H NMR, and FTIR. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of twin‐tail tadpole‐shaped (cyclic polystyrene)‐ block‐[linear poly (tert‐butyl acrylate)]2 by combination of glaser coupling reaction with living anionic polymerization and atom transfer radical polymerization

The twin‐tail tadpole‐shaped (cyclic polystyrene)‐block‐[linear poly (tert‐butyl acrylate)]₂ [(c‐PS)‐b‐(l‐PtBA)₂] was synthesized by combination of Glaser coupling reaction with atom transfer radical polymerization (ATRP) and living anionic polymerization (LAP). First, the telechelic PS with an active and an ethoxyethyl‐protected hydroxyl groups at both ends was prepared by LAP of St monomers using lithium naphthalenide as initiator and terminated by 1‐ethoxyethyl glycidyl ether. And the alkyne groups were introduced onto each PS end by selectively reaction of active hydroxy group with propargyl bromide in NaH/tetrahydrofuran (THF) system. Then, the intramolecular cyclization was carried out by Glaser coupling reaction in pyridine/Cu(I)Br system in air atmosphere. Finally, the macroinitiator of c‐PS with two bromine groups at the junction point was synthesized via the cleavage of ethoxyethyl group and the subsequent esterification of the deprotected hydroxyl groups with 2‐bromoisobutyryl bromide. The copolymer of (c‐PS)‐b‐(l‐PtBA)₂ was obtained by ATRP of tBA monomers, and the PtBA segment was also hydrolyzed for (cyclic polystyrene)‐block‐(linear polyacrylic acid)₂ [(c‐PS)‐b‐(l‐PAA)₂]. The target copolymers and all intermediates were well characterized by GPC, MALDI‐TOF MS, and ¹H NMR in detail. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Stereoregular polycarbonate synthesis: Alternating copolymerization of CO2 with aliphatic terminal epoxides catalyzed by multichiral cobalt(III) complexes

Completely stereoregular polycarbonate synthesis was achieved with the use of unsymmetric multichiral cobalt‐based complexes bearing a derived chiral BINOL and an appended 1,5,7‐triabicyclo[4.4.0] dec‐5‐ene as catalyst for the copolymerization of CO₂ and aliphatic terminal epoxides at mild conditions. The (S,S,S)‐Co(III) complex 1c with sterically hindered substituent group is more stereoregular catalyst for the copolymerization of CO₂ and racemic propylene oxide to afford a perfectly regioregular poly(propylene carbonate) (PPC), with >99% head‐to‐tail linkages, >99% carbonate linkages, and a K_rel of 24.4 for the enchainment of (R)‐epoxide over (S)‐epoxide. The isotactic PPC exhibits an enhanced glass transition temperature of 47 °C, which is 10–12 °C higher than that of the corresponding irregular polycarbonate. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Tunable poly(hydroxyl urethane) from CO2‐Based intermediates using thiol‐ene chemistry

CO₂‐based, crosslinked poly(hydroxyl urethane)s (PHUs) are accessed via a set of efficient reactions based on the addition chemistry of thiol‐ene and amines‐cyclic carbonates. This strategy to utilize 5‐membered cyclic carbonates produced from CO₂ is robust, facile, modular, and atomically efficient in nature. The thiol‐ene reaction was utilized to access bis(cyclic carbonate), tris(cyclic carbonate), and tetrakis(cyclic carbonate) in quantitative yield from 4‐vinyl‐1,3‐dioxolan‐2‐one and thiols. Multi‐functional cyclic carbonates were simply mixed with diethylenetriamine and/or 1,6‐diaminohexane to generate crosslinked PHUs from 25 to 80 °C. These materials are easy to scale‐up and are potential candidates in many applications such as coatings, binders, and resins. The resulting polymers have glass transition temperatures between ?1 and 16 °C and thermal decomposition temperatures from 190 to 230 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Statistical copolymers of norbornene and 5‐vinyl‐2‐norbornene by a ditungsten complex mediated ring‐opening metathesis Polymerization: Synthesis,thermal properties,and kinetics of thermal decomposition

Statistical copolymers of norbornene (NBE) with 5‐vinyl‐2‐norbornene (VNBE) were prepared by ring‐opening metathesis polymerization, employing the triply bonded ditungsten complex Na[W₂(μ‐Cl)₃Cl₄(THF)₂].(THF)₃. NMR measurements revealed that the side vinyl groups of the VNBE monomer remain intact during the copolymerization reaction. The reactivity ratios were estimated using the Finemann–Ross (FR), the inverted FR, and the Kelen–Tüdos graphical methods. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions, which were derived using the monomer reactivity ratios. The glass transition temperatures, T_g, of the copolymers were measured by differential scanning calorimetry measurements and were examined in the frame of several theoretical equations allowing the prediction of these T_g values. The best fit was obtained using methods that take into account the monomer sequence distribution of the copolymers. Finally, the kinetics of the thermal decomposition of the copolymers was studied by thermogravimetric analysis in the frame of the Ozawa–Flynn–Wall and Kissinger methods. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4835–4844     

Thermal radical initiator derivatives based on O‐imino‐isourea: Synthesis,polymerization, and characterization

The new thermal radical initiators (TRIs) with linear and cyclic type groups based on derivatives of O‐imino‐isourea have been designed and synthesized. The radical polymerization property of the synthesized TRI derivatives as a radical initiator in n‐butyl acrylate was monitored by differential scanning calorimetry analysis. TRI derivatives with linear type groups, such as 3‐PenDCC, 3‐HexDCC, and 4‐HepDCC, showed peak temperatures (T_peak) of 80–84 °C, whereas those with cyclic type groups, such as C‐PenDCC, C‐HexDCC, and C‐HepDCC, exhibited a wide T_peak distribution in the 74–87 °C range. The polymerization efficiency using new TRIs in n‐butyl acrylate was elaborately identified from the molecular weights and conversion obtained using gel permeation chromatography analysis and NMR spectroscopy. To consider their possible application to automotive clearcoats, the real‐time evolution of the rheological properties of clearcoat resins during the crosslinking process with newly synthesized TRI derivatives was measured, confirming the different crosslinking kinetics of TRI derivatives in real thermal curing process. The results were found to be well correlated with data from the radical polymerization experiments of TRIs. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3593–3600.     

Cyclic poly(lactide)s via the ROPPOC method catalyzed by alkyl‐ or aryltin chlorides

A comparison of tributyltin chloride, dibutyltin dichloride, and butyltin trichloride as catalysts of ring‐opening polymerizations (ROPs) of l‐lactides at 160 °C in bulk reveals increasing reactivity in the above order, but only the least reactive catalysts, Bu₃SnCl, yield a uniform reaction product, namely cyclic poly(L‐lactide)s with weight average molecular weights (M_w's) in the range of 40,000–80,000. A comparison of dimethyltin , dibutyltin , and diphenyltin dichlorides resulted in the following order of reactivity: Me₂SnCl₂ < Bu₂SnCl₂ < <Ph₂SnCl₂. In this series also, the most reactive catalyst yields cyclic polylactides, but the extent of cyclization varies with the molecular weight. The formation of cyclic polylactides is explained by ROP combined with simultaneous polycondensation involving end‐to‐end cyclization (ROPPOC method). ROP of meso‐lactide at 80 or 60 °C yields even‐numbered linear chains as main products, a result supporting the ROPPOC mechanism. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 952–960     

Synthesis of amphiphilic tadpole‐shaped copolymers by combination of glaser coupling with living anionic polymerization and ring‐opening polymerization

The tadpole‐shaped copolymers polystyrene (PS)‐b‐[cyclic poly(ethylene oxide) (PEO)] [PS‐b‐(c‐PEO)] contained linear tail chains of PS and cyclic head chains of PEO were synthesized by combination of Glaser coupling with living anionic polymerization (LAP) and ring‐opening polymerization (ROP). First, the functionalized polystyrene‐glycerol (PS‐Gly) with two active hydroxyl groups at ω end was synthesized by LAP of St and the subsequent capping with 1‐ethoxyethyl glycidyl ether and then deprotection of protected hydroxyl group in acid condition. Then, using PS‐Gly as macroinitiator, the ROP of EO was performed using diphenylmethylpotassium as cocatalyst for AB₂ star‐shaped copolymers PS‐b‐(PEO‐OH)₂, and the alkyne group was introduced onto PEO arm end for PS‐b‐(PEO‐Alkyne)₂. Finally, the intramolecular cyclization was performed by Glaser coupling reaction in pyridine/Cu(I)Br/N,N,N′,N″,N″‐pentamethyldiethylenetriamine system under room temperature, and tadpole‐shaped PS‐b‐(c‐PEO) was formed. The target copolymers and their intermediates were well characterized by size‐exclusion chromatography, proton nuclear magnetic resonance spectroscopy, and fourier transform infrared spectroscopy in details. The thermal properties was also determined and compared to investigate the influence of architecture on properties. The results showed that tadpole‐shaped copolymers had lower T_m, T_c, and X_c than that of their precursors of AB₂ star‐shaped copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Tunable Self‐Assembly of Triazole‐Linked Porphyrin–Polymer Conjugates

The convergence of supramolecular chemistry and polymer science offers many powerful approaches for building functional nanostructures with well‐defined dynamic behaviour. Herein we report the efficient “click” synthesis and self‐assembly of AB₂‐ and AB₄‐type multitopic porphyrin–polymer conjugates (PPCs). PPCs were prepared using the copper(I)‐catalysed azide–alkyne cycloaddition (CuAAC) reaction, and consisted of linear polystyrene, poly(butyl acrylate), or poly(tert‐butyl acrylate) arms attached to a zinc(II) porphyrin core via triazole linkages. We exploit the presence of the triazole groups obtained from CuAAC coupling to direct the self‐assembly of the PPCs into short oligomers (2–6 units in length) via intermolecular porphyrinatozinc–triazole coordination. By altering the length and grafting density of the polymer arms, we demonstrate that the association constant of the porphyrinatozinc–triazole complex can be systematically tuned over two orders of magnitude. Self‐assembly of the PPCs also resulted in a 6 K increase in the glass transition temperature of the bulk material compared to a non‐assembling PPC. The modular synthesis and tunable self‐assembly of the triazole‐linked PPCs thus represents a powerful supramolecular platform for building functional nanostructured materials.     

Extension of the chain‐end,free‐volume theory for predicting glass temperature as a function of conversion in hyperbranched polymers obtained through one‐pot approaches

Compared with linear polymers, more factors may affect the glass‐transition temperature (T_g) of a hyperbranched structure, for instance, the contents of end groups, the chemical properties of end groups, branching junctions, and the compactness of a hyperbranched structure. T_g's decrease with increasing content of end‐group free volumes, whereas they increase with increasing polarity of end groups, junction density, or compactness of a hyperbranched structure. However, end‐group free volumes are often a prevailing factor according to the literature. In this work, chain‐end, free‐volume theory was extended for predicting the relations of T_g to conversion (X) and molecular weight (M) in hyperbranched polymers obtained through one‐pot approaches of either polycondensation or self‐condensing vinyl polymerization. The theoretical relations of polymerization degrees to monomer conversions in developing processes of hyperbranched structures reported in the literature were applied in the extended model, and some interesting results were obtained. T_g's of hyperbranched polymers showed a nonlinear relation to reciprocal molecular weight, which differed from the linear relation observed in linear polymers. T_g values decreased with increasing molecular weight in the low‐molecular‐weight range; however, they increased with increasing molecular weight in the high‐molecular‐weight range. T_g values decreased with increasing log M and then turned to a constant value in the high‐molecular‐weight range. The plot of T_g versus 1/M or log M for hyperbranched polymers may exhibit intersecting straight‐line behaviors. The intersection or transition does not result from entanglements that account for such intersections in linear polymers but from a nonlinear feature in hyperbranched polymers according to chain‐end, free‐volume theory. However, the conclusions obtained in this work cannot be extended to dendrimers because after the third generation, the end‐group extents of a dendrimer decrease with molecular weight. Thus, it is very possible for a dendrimer that T_g increases with 1/M before the third generation; however, it decreases with 1/M after the third generation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1235–1242, 2004     

Synthesis of poly(isopropenylphenoxy propylene carbonate) and its facile side‐chain functionalization into hydroxy‐polyurethanes

4‐Isopropenyl phenol ( 4‐IPP ) is a versatile dual functional intermediate that can be prepared readily from bisphenol‐A ( BPA ). Through etherification with epichlorohydrin to the phenolic group of 4‐IPP , it can be converted into 4‐isopropenyl phenyl glycidyl ether ( IPGE ). On further reaction with carbon dioxide in the presence of tetra‐n‐butyl ammonium bromide ( TBAB ) as the catalyst, IPGE was transformed into 4‐isopropenylphenoxy propylene carbonate ( IPPC ) in 90% yield. Cationic polymerization of IPPC with strong acid such as trifluoromethanesulfonic acid or boron trifluoride diethyl etherate as the catalyst at ?40 °C gave a linear poly(isopropenylphenoxy propylene carbonate), poly( IPPC ), with multicyclic carbonate groups substituted uniformly at the side‐chains of the polymer. The cyclic carbonate groups of poly( IPPC ) were further reacted with different aliphatic amines and diamines resulting in formation of polymers with hydroxy‐polyurethane on side‐chains. Syntheses, characterizations of poly( IPPC ) and its conversion into hydroxy‐polyurethane crosslinked polymers were presented. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 802–808     

A macromonomer approach to the synthesis of poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane‐graft‐dimethyl siloxane)

Poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane (ECVP)‐graft‐dimethyl siloxane) copolymers were prepared using a macromonomer approach. Poly(dimethyl siloxane) (PDMS) macromonomers were prepared by living anionic polymerization of cyclosiloxanes followed by sequential chain‐end capping with allyl chloroformate. These macromonomers were then copolymerized with ECVP. MALDI‐ToF mass spectrometry and ¹H NMR spectroscopy were used to show that the macromonomers had approximately 80% of the end groups functionalized with allyl carbonate groups. Gradient polymer elution chromatography showed that high yields of the graft copolymers were obtained, along with only small fractions of the PECVP and PDMS homopolymers. Differential scanning calorimetry showed that the low glass transition temperature (T_g) of the PDMS component could be maintained in the graft copolymers. However, the T_g was a function of polymer composition and the polymers produced had T_gs that ranged from ?50 to ?120 °C. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013