Organostibine mediated controlled/living random copolymerization of styrene and methyl methacrylate

The first example of organostibine mediated controlled/living random copolymerization of styrene(St) and methyl methacrylate(MMA) was achieved by heating a solution of St/MMA/organostibine mediator at 100 °C or St/MMA/organostibine mediator/AIBN with various monomer feed ratios at 60 °C.The addition of AIBN significantly decreased the reaction temperature and enhanced the rate of copolymerization.The structure of poly(St-co-MMA) was verified by 1H NMR.The reactivity ratios at 60 °C were determined by the extended Kelen-Tüds method to be YSt = 0.40 and YMMA = 0.44.The ln([M]0/[M]) increased linearly with increasing reaction time.The number-average molecular weights of poly(St-co-MMA) increased linearly with conversion.Poly(St-co-MMA) with expected number-average molecular weight and low polydispersity index was formed.The living characteristic was further confirmed by chain-extension of poly(St-co-MMA) to form poly(St-co-MMA)-b-PMMA.

Influence ofβ-nucleating Compound Agents on the Mechanical Properties and Crystallization Behavior of Polypropylene Random Copolymer

A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.

Rapid synthesis of biodegradable poly(epsilon-caprolactone-co-p-dioxanone) random copolymers under microwave irradiation

Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In...

Micelle-crosslinked hydrogels with stretchable,self-healing,and selectively adhesive properties:Random copolymers work as dynamic yet self-sorting domains

The design of crosslinking domains is a vital factor to create functional hydrogels with controlled physical,mechanical,and adhesive properties.This paper demonstrates versatile synthetic systems of micelle-crosslinked hydrogels with highly stretchable,self-healing,and selectively adhesive properties.For this,methacrylate-bearing random copolymer micelles are designed as physical and covalent crosslink domains via the self-assembly of amphiphilic random copolymers carrying hydrophilic poly(ethylene glycol)(PEG),hydrophobic butyl or dodecyl groups,and methacrylate-terminal PEG in water.The size,aggregation number,and pendant methacrylate number of the micelles are controlled by the composition and degree of polymerization.Hydrogels are efficiently obtained from the free radical polymerization of hydrophilic monomers such as PEG acrylate and acrylamide in the presence of the micelle crosslinkers in water.Owing to the dynamic yet selective chain exchange properties of the micelle domains,the hydrogels are highly stretchable up to over 1000%and show self-healing and selectively adhesive properties.The self-healing of hydrogels is promoted upon heating due to the fast chain exchange of the micelle domains,whereas hydrogels consisting of micelles with different alkyl groups are never adhesive because of their self-sorting properties.

Effect of Long Chain Branching on the Rheological Behavior,Crystallization and Mechanical Properties of Polypropylene Random Copolymer

Long chain branched polypropylene random copolymers(LCB-PPRs) were prepared via reactive extrusion with the addition of dicumyl peroxide(DCP) and various amounts of 1,6-hexanediol diacrylate(HDDA) into PPR. Fourier transform infrared spectrometer(FTIR) was applied to confirm the existence of branching and investigate the grafting degree for the modified PPRs. Melt flow index(MFI) and oscillatory shear rheological properties including complex viscosity,storage modulus, loss tangent and the Cole-Cole plots were studied to differentiate the LCB-PPRs from linear PPR.Differential scanning calorimetry(DSC) and polarized light microscopy(PLM) were used to study the melting and crystallization behavior and the spherulite morphology, respectively. Qualitative and quantitative analyses of rheological curves demonstrated the existence of LCB. The effect of the LCB on crystalline morphology, crystallization behavior and molecular mobility, and, thereby, the mechanical properties were studied and analyzed. Due to the entanglements between molecular chains and the nucleating effect of LCB, LCB-PPRs showed higher crystallization temperature and crystallinity,higher crystallization rate, more uniformly dispersed and much smaller crystallite compared with virgin PPR, thus giving rise to significantly improve impact strength. Moreover, the LCB-PPRs exhibited the improved yield strength. The mobility of the molecular chain segments, as demonstrated by dynamic mechanical analysis(DMA), was improved for the modified PPRs, which also contributed to the improvement of their mechanical properties.

Ring-opening Copolymerization of ε-Caprolactone and δ-Valerolactone Catalyzed by a 2,6-Bis(amino)phenol Zinc Complex

In combination with methyllithium,a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization ofδ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency,mainly producing cyclic and linear polyvalerolactones,respectively.On the basis of homopolymerization,the ring-opening copolymerization ofε-caprolactone andδ-valerolactone was investigated.The P(CL-co-VL)random copolymers,PCL-b-PVL and PVL-b-PCL diblock copolymers,were prepared by varying the feeding strategy(premixing or sequential feeding).The copolymer composition was adjusted by varying the feeding ratio of two monomers.The structure and thermal properties of obtained polymers were characterized by GPC,1 H-NMR,13 C-NMR,MALDI-TOF mass spectroscopy,and DSC,respectively.

Sequence design in terpolymerization ofε-caprolactone,CO_(2) and cyclohexane oxide:Random ester-carbonate distributions lead to large-span tunability

It is of great interest to make a degradable material widely tailorable to replace petroleum-derived products among diverse applications.Here,we report the construction of a new multi-purpose degradable material for the first time via a simple ternary copolymerization system comprisingε-caprolactone(ε-CL),cyclohexane oxide(CHO)and CO_(2).Under low pressure of 1 bar∼5 bar,the ring-opening polymerization(ROP)ofε-CL and ring-opening copolymerization(ROCOP)of CO_(2) and CHO can simultaneously proceed.The carbonate units are randomly distributed on the polymer chain.These random terpolymers have controllable molar mass(10-106 kDa)and compositions(4-33 mol%CO_(2)).And the obtained materials show large-span tunability from tough plastic to elastomer and even adhesive.

Distinctive Polymorphism-like Isodimorphism in Poly(propylene succinate-ran-propylene fumarate)

Co-crystallization of different monomeric units fundamentally contributes to the versatile and tunable performance of random copolymers.At present,the crystallization manners of random binary copolymers have been divided into three categories:isomorphism,isodimorphism and comonomer exclusion.Each category,however,has its own advantages and disadvantages.Therefore,it is challenging to design and prepare random copolymer sharing the advantages of isomorphism and isodimorphism through a new co-crystallization manner beyond the ones already exist.On the basis of previous study on poly(alkylene succinate-ran-alkylene fumarate)whose co-crystallization can be extensively and finely regulated by simply varying the chemical structure of alkylene,random copolymers of poly(propylene succinate-ranpropylene fumarate)(PPSF)are synthesized using 1,3-propanediol as the diol source.The thermal properties and crystal structure of PPSF are investigated,and,intriguingly,it is proved that PPSF is an isodimorphism system while displays similar composition-dependent thermal properties and crystallinity as isomorphism.That is,PPSF exhibits a novel co-crystallization behavior that has rarely been discovered,which would combine the advantages of both isomorphism and isodimorphism.Consequently,PPSF could be termed as a new-type,special compositiondependent polymorphism.Besides,the altering of PPS-like to PPF-like crystal structure of PPSF when changing chain composition has been proved to originate from the shift of dominant inter-segment interaction from van der Waals forces to strong hydrogen-bonding interaction.This work enriches the co-crystallization manner of random copolymers,leading to more diverse performance design of polymer materials.

Preparation and Properties of Super-hydrophobic Surface by Fluorinated Copolymers

1 Rusults Fig.1 Surface morphologies of the PMMA-PFAEA copolymer filmsa-e, Random copolymer, a-e, synthesized by micro emulsion polymerization,a)b), MMA:FAEA=2:1, c) d), MMA:FAEA=5:1; e) synthesized by solution polymerization, MMA:FAEA=7:3; f) Block copolymer, synthesized by RAFT polymerization, MMA:FAEA=4:1, all solution concentration 1×10-2g/mL Super-hydrophobic surfaces have attracted significant attention recently, and various preparing methods have been reported. Besides these preparing methods, s...