A new tricrystalline triblock terpolymer by combining polyhomologation and ring‐opening polymerization. synthesis and thermal properties

New tricrystalline triblock terpolymers, polyethylene‐block‐poly(ε‐caprolactone)‐block‐poly(L‐lactide) (PE‐b‐PCL‐b‐PLLA), were synthesized by ROP of ε‐caprolactone (CL) and L‐lactide (LLA) from linear ω‐hydroxyl polyethylene (PE‐OH) macroinitiators. The linear PE‐OH macroinitiators were prepared by C1 polymerization of methylsulfoxonium methylide (polyhomologation). Tin(II) 2‐ethylhexanoate was used as the catalyst for the sequential ROP of CL and LLA in one‐pot polymerization at 85 °C in toluene (PE‐OH macroinitiators are soluble in toluene at 80 °C). ¹H NMR spectra confirmed the formation of PE‐b‐PCL‐b‐PLLA triblock terpolymers through the appearance of the characteristic proton peaks of each block. GPC traces showed the increase in the number average molecular weight from PE‐OH macroinitiator to PE‐b‐PCL, and PE‐b‐PCL‐b‐PLLA corroborating the successful synthesis. The existence of three crystalline blocks was proved by DSC and XRD spectroscopy. © 2019 The Authors. Journal of Polymer Science Part A: Polymer Chemistry published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2450–2456     

A new periodic pattern with five‐neighbored domain packing from ABC triblock terpolymer/B homopolymer blend

Self‐assembled structures from poly(isoprene‐b‐styrene‐b‐2‐vinylpyridine)(ISP)/styrene homopolymer blend were investigated. Five terpolymers whose total molecular weight, M, is in the narrow range of 121k < M < 214k, and volume fractions of the center block polystyrenes, ?_S, are similar at around 0.55, were prepared as parent block terpolymers. Their ?_P/?_I ratios, used as an indicator of asymmetry, are varied in the range 0.32 < ?_P/?_I < 2.46. Three low‐molecular weight styrene homopolymers with molecular weights of 3k, 9k, and 12k, respectively, were mixed with those block terpolymers to produce blends with almost constant styrene content within the range 0.65 < ?_S < 0.68. Both ISP/S(3k) and ISP/S(12k) blend series show a morphological transition from tetragonally packed cylinders (TPC) to double hexagonal structure (DHS) with hexagonally arrayed polyisoprene cylinders, each surrounded by six thin cylinders as satellites. If one focuses on ISP‐III(150k)/S blends whose ?_P/?_I is 0.88, TPC for ISP‐III/S(3k) was transformed to DHS for ISP‐III/S(12k), evidently due to the molecular weight effect of the added homopolymer. Finally a new periodic pattern, having P cylinders surrounded by five I cylinders each, has been discovered from ISP‐III/S(9k) at overall composition of ?_I/?_S/?_P = 0.17/0.68/0.15 and polystyrene block/styrene homopolymer ratio of w_S(b)/w_S(h) = 1.4. This structure was confirmed to possess hexagonal symmetry with larger unit cell than regular patterns ever known by X‐ray diffraction experiment. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 907–911     

Regular conjugated terpolymers comprising two different acceptors and bithiophene donor in repeating group: Effect of strong and weak acceptors on semiconducting properties

Diketopyrrolopyrrole (DPP)‐based terpolymers—P(DPP‐TPyT) and P(DPP‐T3MTT)—bearing bithiophene donating groups and weak accepting units such as pyridine (Py) or methyl thiophene‐3‐carboxylate (3MT), in the polymer backbone, were successfully synthesized. Although the two polymers had similar physical and electrochemical properties, grazing incidence X‐ray diffraction patterns of P(DPP‐TPyT) and P(DPP‐T3MTT) showed mixed and edge‐on orientations, respectively, in thermally annealed films. Accordingly, the P(DPP‐T3MTT) showed twice the hole mobility of P(DPP‐TPyT) in a thin‐film transistor, and a blended film of P(DPP‐T3MTT) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC₇₁BM) showed better power conversion efficiency in a polymer solar cell. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1339‐1347     

Poly(acrylate‐b‐styrene‐b‐isobutylene‐b‐styrene‐b‐acrylate) Block Copolymers via Carbocationic and Atom Transfer Radical Polymerizations

A series of polyacrylate‐polystyrene‐polyisobutylene‐polystyrene‐polyacrylate (X‐PS‐PIB‐PS‐X) pentablock terpolymers (X=poly(methyl acrylate) (PMA), poly(butyl acrylate) (PBA), or poly(methyl methacrylate) (PMMA)) was prepared from poly (styrene‐b‐isobutylene‐b‐styrene) (PS‐PIB‐PS) block copolymers (BCPs) using either a Cu(I)Cl/1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) or Cu(I)Cl/tris[2‐(dimethylamino)ethyl]amine (Me₆TREN) catalyst system. The PS‐PIB‐PS BCPs were prepared by quasiliving carbocationic polymerization of isobutylene using a difunctional initiator, followed by the sequential addition of styrene, and were used as macroinitiators for the atom transfer radical polymerization (ATRP) of methyl acrylate (MA), n‐butyl acrylate (BA), or methyl methacrylate (MMA). The ATRP of MA and BA proceeded in a controlled fashion using either a Cu(I)Cl/PMDETA or Cu(I)Cl/Me₆TREN catalyst system, as evidenced by a linear increase in molecular weight with conversion and low PDIs. The polymerization of MMA was less controlled. ¹H‐NMR spectroscopy was used to elucidate pentablock copolymer structure and composition. The thermal stabilities of the pentablock copolymers were slightly less than the PS‐PIB‐PS macroinitiators due to the presence of polyacrylate or polymethacrylate outer block segments. DSC analysis of the pentablock copolymers showed a plurality of glass transition temperatures, indicating a phase separated material.     

Acrylate terpolymer in fabrication of medicated skin patches

An acrylate based pressure sensitive adhesive (PSA) was synthesized to design a drug‐in‐adhesive (DIA) type transdermal therapeutic system (TTS) for nitroglycerin used in the treatment of angina pectoris. 2‐Ethylhexyl acrylate (EHA), methyl methacrylate (MMA) and acrylic acid (AA) were used to synthesize the PSA by free radical solution polymerization. The effects of reaction time, reaction temperature, initiator concentration and solvent on polymerization were studied. The synthesized terpolymer was characterized by ¹H‐NMR, FT‐IR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) and also evaluated for intrinsic viscosity, refractive index, peel strength, moisture uptake and skin irritation potential. The PSA was used to develop DIA type patches of nitroglycerin. The patches were cast using solvent evaporation technique and dried at controlled temperature. The patches were evaluated for thickness uniformity, weight variation, peel strength and moisture pick‐up. The percent drug content and in vitro drug release was determined by high pressure liquid chromatography (HPLC) method. On the basis of in vitro release profile, patches were selected for in vitro skin permeation studies. The developed formulation TP‐1 (K = 24.892 mcg/cm²/hr) followed zero‐order rate kinetics and showed better skin permeation rate in comparison to the marketed TTS (MTTS) (K = 17.413 mcg/cm²/hr). TP‐1 was subjected to stability testing for a period of 1 year according to ICH guidelines. The patches were found to be stable and an expiry date of 2 years was predicted with storage at 25 °C or below. Copyright © 2001 John Wiley & Sons, Ltd.     

Mechanical,Thermal, and Rheological Properties of EPDM-graft-methyl Methacrylate and Styrene (EPDM-g-MS)/Methyl Methacrylate-Styrene Copolymer (MS Resin) Blends

EPDM-graft-methyl methacrylate and styrene (EPDM-g-MS) were synthesized by solution graft copolymerization of methyl methacrylate (MMA) and styrene (St) onto ethylene-propylene-diene terpolymer (EPDM). EPDM-g-MS/MS resin blends (MES) tht were prepared by melt blending EPDM-g-MS and methyl methacrylate-styrene copolymer (MS resin). The mechanical properties, compatibility, thermal stabilities and rheological properties of MES were studied by the pendulum impact tester and the tension tester, differential scanning calorimetric (DSC), thermogravimetry analysis (TGA), and the capillary rheometry, respectively. The results showed that EPDM-g-MS had an excellent toughening effect on MS resin; the notched Izod impact strength of MES reached 20.7 kJ/m² when EPDM content in MES was 25 wt%, about 14 times that of MS resin. EPDM-g-MS and MS resin were partially compatible, and the compatibility increased with an increasing MMA/St ratio of EPDM-g-MS. MES had excellent heat-resistance, which increased as the EPDM content in MES and MMA/St ratio of EPDM-g-MS rose. MES melt flow confirmed pseudoplastic flow characteristics. The apparent viscosity (η _a ) of MES decreased with an increasing shearing rate (γ) and temperature, but increased with an increasing EPDM content in MES and MMA/St ratio of EPDM-g-MS. The flow activation energy of MES was lower than that of MS resin.     

三元乙丙橡胶的13C-NMR定量分析

用13C核磁共振波谱法对三元乙丙橡胶进行了研究，通过图谱中各个峰的积分值，并用特定的计算公式测定了三元乙丙橡胶中乙烯及第三单体乙叉降冰片烯的含量，为红外光谱批量的定量分析建立了基准化的标定。     

沉淀法制备EPDM-g-MAH/CaCO_3复合材料及其性能的表征

提供了三元乙丙橡胶(EPDM)交联的一种方法.以二甲苯为溶剂,溶液法制备马来酸酐(MAH)接枝EPDM,然后向溶液中加入适量碳酸钙(CaCO3),与已接枝的马来酸酐(MAH)反应.待反应完全后,滴加丙酮作为沉淀剂,沉淀物真空干燥,制得EPDM-g-MAH/CaCO3弹性体复合材料.溶解、溶胀及拉伸性能测试结果表明,复合材料样品已形成有效的交联,且材料的抗张强度、断裂伸长率和模量均得到较大幅度的提高,当CaCO3含量达到体系总重的20%时,复合材料呈现最佳力学性能.上述实验结果是因为碱性的CaCO3的Ca2+可以与接枝在EPDM上的MAH发生配合反应,进而成为EPDM的交联中心,形成有效交联,从而促进了EPDM机械性能的提高,ATR-FTIR和TGA的测试结果被用于证实上述观点.     

Polymeric positive-temperature-coefficient materials: dynamic curing effect

The object of this work was to prepare high-density polyethylene (HDPE)/ethylene–propylene–diene terpolymer (EPDM)/conductive carbon black (CB) composites by dynamic curing and to characterize the positive-temperature-coefficient (PTC) performances of the composites.EPDM and dicumyl peroxide were preblended in a research mill. The roll-milled strands were blended with HDPE and CB in a Haake mixer. The sheet resistivity and morphology of the HDPE/EPDM/CB composites with or without the dynamic curing process were investigated. It was concluded that the dynamically cured blends exhibit better PTC performance than the simple blends without dynamic curing. The effects of shear intensity and dicumyl peroxide content during the dynamic curing process were discussed for the PTC characteristics of the HDPE/EPDM/CB composites.     

投料顺序对动态硫化PP／EPDM性能影响及其机理的研究

针对ＰＰ降解在ＰＰ／ＥＰＤＭ动态硫化中对体系产生的不利影响。考察了四种不同投料顺序对ＰＰ／ＥＰＤＭ动态硫化物的冲击韧性，加工流动性，交联程度和断面形貌等宏观和微观性能，并进行了不同ＥＰＤＭ含量的动态硫化和非硫化ＰＰ／ＥＰＤＭ的性能比较。结果表明，优化投料顺序能实现对动态硫化体系中化学反应对象和化学反应程度的有效干预。