Molecular Weight Products Research Articles

Very-high-molecular-weight vs high-molecular-weight hyaluronic acid injections show long-term sustained benefits in the treatment of osteoarthritis of the knee: a 15-year Indian cohort study

IntroductionLack of confidence in intra-articular hyaluronic acid injections for osteoarthritis (OA) may result from conflicting guidelines and pooling of results for different molecular weight products. ObjectivesThe objectives were to determine responder rates to injections of very-high-molecular-weight hyaluronic acid (VHMW-HA) vs high-molecular-weight hyaluronic acid (HMW-HA) for knee OA and treatment efficacy measured by the interval between follow-up injections. MethodsA retrospective analysis of a 15-year cohort from a single center. Inclusion criteria: adults with Kellgren-Lawrence Grade III or IV knee OA treated with hyaluronic acid injections. Subjects were stratified into 2 groups based on the molecular weight of the hyaluronic acid. Outcome measures were responder rates with improvement in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores of >30% from baseline vs nonresponders; those with a response lasting >6 months after each injection were considered sustained responders. ResultsIn total, 2037 (female 1467 [72.02%] and male 570 [27.98%]) patients were treated. The overall primary responder rate was 73.44% (1496). VHMW-HA had significantly higher primary responders (75.21% vs 70.22%, P = .015) and significantly lower nonresponders (24.79% vs 29.78%, P = .015). As a subset of primary responders, the sustained responders had greater responses with VHMW-HA vs HMW-HA (85.54% vs 67.06%, P < .0001) and lower dropouts (14.46% vs 32.94%, P < .0001). The average interval between the first and the third injections was longer for VHMW-HA vs HMW-HA—5.67 vs 1.95 years (P < .0001). ConclusionsAbout 73.44% of subjects responded to treatment with intra-articular hyaluronic acid. The sustained response was greater in VHMW-HA vs HMW-HA and VHMW-HA has a longer duration of effect than HMW-HA.

Hydrolytic degradation of polylactide/polybutylene succinate blends with bioactive glass

Polylactides (PLAs) have been vastly studied for biomedical engineering applications, but their rigidness limits their use. Blending them with more flexible polymers, such as polybutylene succinate (PBSu), results in softer materials, expanding the range of possible applications. However, the biopolymers lack bioactivity, which can be overcome by adding bioactive glass. Combining the inorganic phase with the organic phase (especially with blends) results in a complex material. Therefore, understanding the hydrolytic degradation of each component is crucial. In this context, we report on processing polylactide and polybutylene succinate (PLA/PBSu) blends and their composites (30 wt% of bioactive glass 13‐93, BaG). The impact of blending and compounding with BaG on the final product's molecular weight and mechanical properties and the BaG dispersion in the polymer matrices was assessed. In addition, in vitro degradation in PBS was studied. While the degradation of the polymer was assessed by GPC, the BaG dissolution was quantified by ICP-OES. Blending decreased the initial mechanical properties and molecular weight, and compounding with BaG further decreased the initial mechanical properties. During the immersion in PBS, blending accelerated the loss of mechanical properties and molecular weight, while BaG accelerated the degradation of PLA-containing materials but had little effect on PBSu. Blending and compounding with BaG enabled us to produce materials with a wide range of mechanical properties: bending strength of 34–125 MPa, shear strength of 22–47 MPa and bending modulus of 1.1–3.9 GPa. The selection of tailorable properties of these polymer/BaG composites enables their application for tissue engineering of bone to soft tissue.

Efficient extraction of chitin from crustacean waste via a novel ternary natural deep eutectic solvents

Extraction of chitin from crustacean waste with acidic natural deep eutectic solvents (NADESs) is usually accompanied by degradation of chitin, which lowers the yield and molecular weight of product. Herein, this study proposed a eco-friendly and feasible route for effectively improving the yield and molecular weight of chitin by introducing N-acetyl-D-glucosamine into ternary NADESs. A high molecular weight chitin with molecular weight of 3.92 × 105 Da, purity of 90.2% and yield of 85.6% was obtained from crab shell. Compared with conventional acid/alkali and binary NADESs method, the maximum yield of chitin extracted by ChCl-G-FA2 was increased by 1.57 times and 1.39 times respectively. Molecular weight of chitin was 3.16 times that of acid/alkali method. Recycling performance evaluation revealed that the purity of chitin could still reach 80.4% after five cycles of NADESs. This study provided a eco-friendly utilization strategy for crustacean waste based on multifunctional NADESs.

Study of the Nature of the Influence of some Oligophosphonates on the Rheological Properties of High-Density Polyethylene

High molecular weight compounds with organophosphorus backbones are usually obtained by polycondensation of phosphorus-containing monomers, leading, most often, to products of low molecular weight at low yields. This fact is explained [1] by several reasons: a decrease in the reactivity of the second functional group of the monomer after the first one has reacted; the possibility of the formation of cyclic compounds; hydrolytic instability of the phosphorus-heteroatom bond (usually P-O, P-N), etc.

Rotation‐restricted strategy to synthesize high molecular weight polyethylene using iminopyridyl nickel and palladium catalyst

Most of the iminopyridyl Ni (II) and Pd (II) catalysts are reported to oligomerize ethylene or yield very low molecular weight polyethylene. Moreover, the molecular weight of product is not sensitive to ligand sterics. In this contribution, we demonstrate that the bulky rotation‐restricted substituents incorporated into iminopyridyl Ni (II) and Pd (II) catalysts that provide the right orientation are highly effective in retarding the chain transfer. Thus, (2,6‐bis(10,11‐dihydro‐5H‐dibenzo[a,d][7]annulen‐5‐yl)‐4‐methylphenyl)‐1‐(pyridin‐2‐yl)methanimine nickel (II) bromide (Ni3) and (2,6‐bis(10,11‐dihydro‐5H‐dibenzo[a,d][7]annulen‐5‐yl)‐4‐methylphenyl)‐1‐(pyridin‐2‐yl)methanimine palladium (II) methyl chloride (Pd3) with the phenyl substituents fixed in the diarylmethyl moiety produce polyethylene or functionalized polyethylene (ethylene‐MA copolymer) with high Mn values up to 2.5 × 104 g mol−1, while allowing the high MA incorporation (3.2%–13.8%). In addition, the effects on the (co)polymerization behavior as a function of rotation‐restricted substituent variations (free rotation, restricted rotation and fixation) were systemically studied. As a result, various molecular weight polyethylene and ethylene‐MA copolymer with high MA incorporation ratio were also obtained in this system.

Immobilized Cell Physiology Imaging and Stabilization of Enzyme Cascade Reaction Using Recombinant Cells Escherichia coli Entrapped in Polyelectrolyte Complex Beads by Jet Break-Up Encapsulator

A novel, high performance, and scalable immobilization protocol using a laminar jet break-up technique was developed for the production of polyelectrolyte complex beads with entrapped viable Escherichia coli cells expressing an enzyme cascade of alcohol dehydrogenase, enoate reductase, and cyclohexanone monooxygenase. A significant improvement of operational stability was achieved by cell immobilization, which was manifested as an almost two-fold higher summative product yield of 63% after five cascade reaction cycles as compared to the yield using free cells of 36% after the maximum achievable number of three cycles. Correspondingly, increased metabolic activity was observed by multimodal optical imaging in entrapped cells, which was in contrast to a complete suppression of cell metabolism in free cells after five reaction cycles. Additionally, a high density of cells entrapped in beads had a negligible effect on bead permeability for low molecular weight substrates and products of cascade reaction.

Telechelic Carboxyl‐Terminated Polynorbornenes and Copolym‐ers via Chain‐Transfer Ring‐Opening Metathesis Polymerization

AbstractCarboxyl‐terminated polynorbornenes (CTPNB) have been prepared via ring‐opening metathesis polymerization (ROMP) catalyzed by Grubbs II catalyst (G2) in the presence of maleic acid (MA) as a chain transfer agent (CTA). The influences of reaction conditions on the molecular weight of products, including molar ratios of C=C/G2, C=C/CTA and amount of solvent were investigated. The results indicated that the molecular weight of CTPNBs could be controlled by varying the molar ratio of C=C/G2 or C=C/CTA. In addition, norbornene (NB) was copolymerized with cyclooctene (COE) in order to obtain carboxyl‐terminated copolymers via chain‐transfer ROMP. The unsaturated carboxyl‐terminated (co)polymers were further hydrogenated by using p‐toluenesulfonyl hydrazide/tri‐n‐propylamine reagents. The structures of polymers were characterized by FT‐IR, NMR and MALDI‐TOF mass spectroscopy, and their thermal properties were determined by DSC and TGA.

Establishment of a molecular structure model for classified products of coal-based fulvic acid

Fulvic acid (FA) is used widely in materials, medicine, and agriculture because of its unique chemical properties. FA has good chemical activity due to its molecular structure which contains many functional moieties such as hydroxyl and carboxyl groups. Moreover, FA is biologically compatible enabling its use in medicine is agriculture. The chemical activity and physical properties of FA polymers differ based on its molecular weight. In order to reveal the specific structural characteristics of FA, column chromatography was used to fractionate FA into three different molecular weight products. Elementary analysis, infrared spectroscopy, and 13C nuclear magnetic resonance were used to study the composition and content of the classified FA products. The three different molecular weights of FA all contained carboxyl groups and phenolic hydroxyl groups. Our findings show that the carboxyl group was mostly distributed at the end of the aliphatic chain, while a small portion was connected to the benzene ring. The higher molecular weight FA contained more carboxyl groups, and some oxygen elements were present in the form of carbonyl and ether bonds. The chemical formulas of the three molecular weights were C17H19NO10, C33H27NO23, and C48H37NO36, which were calculated by molecular mechanics and dynamics. The molecular structure of FA was optimised by quantum chemical calculation methods. Finally, the average molecular structure model of FA with different molecular weights was established.

Ethylene-bridged Indenyl-fluorenyl Metallocene Complexes for Efficient Preparation of Allyl-terminated Propylene Oligomers and Polymers via Selective β-Methyl Transfer

Four C1-symmetric ansa-metallocene complexes, C2H4(Ind)(2,7-tBu2-Flu)ZrCl2 (4), C2H4(3-Bn-Ind)(2,7-tBu2-Flu)ZrCl2 (5), C2H4(3-Bn-Ind)(3,6-tBu2-Flu)ZrCl2 (6), and C2H4(3-Bn-Ind)(2,7-tBu2-Flu)HfCl2 (7), were synthesized and characterized. The structures of complexes 4, 5, and 7 were further determined via X-ray diffraction studies. Upon activation with modified methylaluminoxane (MMAO) or AliBu3/[Ph3C][B(C6F5)4] (TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminals via selective β-methyl transfer (β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selective β-Me transfer during the polymerization process, leading to selectivities up to 89% obtained by zirconocene complexes 5 and 6, and up to 91% obtained by hafnocene complex 7. Detailed chain-end analysis by 1H-NMR, 13C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selective β-Me transfer process after two successively primary insertions of the monomer. Further studies concerning the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that both β-Me transfer (major) and β-hydrogen transfer (β-H transfer) (minor) mediated by 5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.

Solvent strategy toward living cationic polymerization of trichloro(N-silyl)phosphoranimine based on Density Functional Calculations and experimental verification

Living cationic polymerization provides a controllable route to prepare a versatile hybrid biomaterial, poly(dichloro)phosphazene. However, the conversion of this multi-step reaction is limited and the mechanistic understanding of the process is incomplete. Thus, the geometric and energetic properties of three process models were designed to determine the interaction mechanism based on Density Functional Calculations. The internuclear distance among counterions and monomers visually demonstrated that [PCl6]− restricted the reactivity of cationic polymerization through interacting with cationic species. The counterion effect was ascertained to be obvious at the beginning of the propagation on the basis of NBO, frontier molecular orbital and thermodynamic analysis. Besides, solvent effect was quantitatively described and solvents were effective for regulating the negative interaction. Therefore, a rational solvent screening model was established based on the solvent polarity and reactivity of monomers. Selected solvents were carried out to prepare oligomeric dichlorophosphazenes and poly(dichloro)phosphazenes to prove the reliability and practicability of the model, showing a significant improvement in conversion and molecular weight of product with the increase in solvent polarity. The findings of this study will provide new insights into the living cationic polymerization of trichloro(N-silyl)phosphoranimine and will be very relevant for a broader community working on polymerization with rational solvent screening via Density Functional Calculations.

A Comparative Study on Emulsion Polymerization Processes of Styrene Initiated by Water-soluble and Oil-soluble Initiators

The solubility of initiator determines its distribution and the roles played in emulsion polymerization as well as the final products, but this is still lack of systematic investigation. The present work focuses on this issue by comparing the kinetic behaviors and product properties of styrene emulsion polymerization initiated by 2,2-azoisobutyronitrile (AIBN) and potassium persulphate (KPS). Compared to KPS-initiated emulsion polymerization, the AIBN-initiated polymerization was found to be insensitive to the type of emulsifier, and have high polymerization rate as well as narrow molecular weight distribution and particle size distribution. This result indicates the effective free radicals are generated in micelles or colloids, which could decrease the proportion of homogeneous nucleation and make the process and product more controllable. As a consequence, there is a linear relationship between molecular weight of product and AIBN concentration in lg-lg coordinate. It provided a reference for the preparation of latexes with specified molecular weight and supported the possibility of the coexistence of multiple free radicals in one micelle or colloid when using oil-soluble initiator.

Synthesis of million molecular weight polyacrylamide with droplet flow microreactors

Microreactors are good platforms to study polymerization, but the production of high molecular weight polymers in small reaction space is rather difficult. To obtain million grams/mole molecular weight product, we developed two microreactors to implement inverse suspension polymerization in separated droplets, working as mini-reactors. Protecting by the lubricant film around droplets, 3600 kg/mol polyacrylamide (PAM) was successfully prepared in 38 min residence time, without any clogging issues. Advanced to the batch reactors, the microreactors offered precise control over the whole polymerization process in terms of reaction time and properties of the products, which facilitated the understanding of the basic laws of reactions. Thermal-initiated and redox-initiated radical polymerizations were both investigated, and the thermal-initiated reaction was found to be suitable for preparing high molecular weight polyacrylamide (>1000 kg/mol). The redox-initiated polymerization was a mixing-controlled reaction, which finished quickly in the microreactor.

Interaction between Cucumber mosaic virus 2b protein and plant catalase induces a specific necrosis in association with proteasome activity

Key messageCucumber mosaic virus(CMV) can induce a specific necrosis onArabidopsisthrough the interaction between the CMV 2b protein and host catalase, in which the ubiquitin–proteasome pathway may be involved.We previously reported that the CMV 2b protein, the viral RNA silencing suppressor, interacted with the H2O2 scavenger catalase (CAT3), leading to necrosis on CMV-inoculated Arabidopsis leaves. We here confirmed that CMV could more abundantly accumulate in the CAT3-knockout mutant (cat3), and that CAT3 makes host plants a little more tolerant to CMV. We also found that the necrosis severity is not simply explained by a high level of H2O2 given by the lack of CAT3, because the recombinant CMV, CMV-N, induced much milder necrosis in cat3 than in the wild type, suggesting some specific mechanism for the necrosis induction. To further characterize the 2b-inducing necrosis in relation to its binding to CAT3, we conducted the agroinfiltration experiments to overexpress CAT3 and 2b in N. benthamiana leaves. The accumulation levels of CAT3 were higher when co-expressed with the CMV-N 2b (N2b) than with CMV-Y 2b (Y2b). We infer that N2b made a more stable complex with CAT3 than Y2b did, and the longevity of the 2b–CAT3 complex seemed to be important to induce necrosis. By immunoprecipitation (IP) with an anti-ubiquitin antibody followed by the detection with anti-CAT3 antibodies, we detected a higher molecular-weight smear and several breakdown products of CAT3 among the IP-proteins. In addition, the proteasome inhibitor MG132 treatment could actually increase the accumulation levels of CAT3. This study suggests that the host proteasome pathway is, at least partially, responsible for the degradation of CAT3, which is manifested in CMV-infected tissues.

Continuous flow protecting-group-free synthetic approach to thiol-terminated poly(ε-caprolactone)

A novel continuous flow protecting-group-free synthetic approach was developed to thiol-terminated poly(ε-caprolactone). Sn(OTf)2 catalyzed unprotected 6-mercapto-1-hexanol initiating chemoselective ring-opening polymerization of ε-caprolactone was conducted in PTFE tubular reactor. This continuous flow polymerization platform achieved quantitative chemoselectivity and fast polymerization that cannot be done in batch. By changing the [monomer]/[initiator] feed ratio, the molecular weights of products were well controlled with narrow molecular weight distributions. The structure of the resultant thiol-terminated poly(ε-caprolactone) was demonstrated by NMR, MALDI TOF MS and SEC.

Synthesis of ultra high molecular weight poly(dimethyldiallyl ammonium chloride)

In the study we reported the synthesis of poly-(dimethyldiallyl ammonium chloride) (PDMDAAC) with ultra high molecular weight. The polymerization method consists in the following: the ultra-high purity monomer synthesized in lab was used as the raw material, and APS as the initiator. APS was added in a lump and the polymerization temperature was increased stepwise to complete the polymerization gradually in 9 h reaction time. The maximum intrinsic viscosity ([η]) of PDMDAAC reached 3.66 dL g–1 at a monomer conversion rate (Conv) of 96.71%. The structure and properties of PDMDAAC were characterized using FTIR, NMR, GPC-MALLS, and DTA-TG. The effects of polymerization conditions, such as the polymerization temperature, m(DMDAAC), m(APS): m(DMDAAC), and m(Na4EDTA): m(DMDAAC), on the [η] and Conv of products were investigated. Meanwhile, the effects of the monomer purity on the [η] of products were compared. The results showed that the types and amount of impurities in monomer solution are two key factors, which affect the polymerization and, thus, the molecular weight of products.

단백질 분해효소를 이용한 연산오계 내장 펩타이드 생산 최적화 및 특성분석

Yeonsan Ogae has been known as supporting health and high efficacy of treatment. In recent days, as the efficacy of functional peptides has known, the optimization of oligo peptides production and its characteristics from Ogae viscera has been performed. Response surface method was used to perform the optimizaion of enzyme hydrolysis. The range of processes was temperature (40, 50 and ), pH(6.0, 7.0 and 8.0), and enzyme(1, 2 and 3%). The degree of hydrolysis, amono acids, molecular weight of products were analyzed. The optimum process of enzyme hydrolysis were determined as temperature , pH 7.5, and enzyme concetration 3%. At optimum conditions, the degree of hydrolysis after 2 h reaction was 75-80%. The total amino acids of amino acid and were 386.15 mg/100 g and 155.26 mg/100 g, respectively. The molecular weight of products by using Maldi-TOF was ranged from 300 to 1,000 Da.

Composite Flooring Quality of Combined Wood Species Using Adhesive from Merbau Wood Extract

Abstract Polyphenol chemical components extracted from merbau (Intsia spp.) wood exhibit a strong affinity for resorcinol and formaldehyde in alkaline conditions, forming a copolymer that could serve as an adhesive. A liquid extract of merbau wood (M) was allowed to copolymerize with resorcinol (R) and formaldehyde (F) under alkaline conditions, with an M:R:F weight ratio of 100:5:10. The course of the reaction and potential mechanisms of copolymerization were scrutinized using Fourier transform infrared spectroscopy, X-ray diffraction, and differential thermal analysis. The adhesive was used to manufacture three-ply composite flooring consisting of a back layer of rubberwood (Hevea brasiliensis), a core layer from sengon (Paraserianthes falcataria) wood, and a face layer with one of seven wood species, namely, sengon, sungkai (Peronema canescens), mangium (Acacia mangium), rubberwood, mahogany (Swietenia spp.), kempas (Koompassia malaccensis), and merbau. The adhesive was spread on the face and back layers of 170 g/m2 single glue line, which was followed by pressing at 11 kg/cm2 for 3 hours at room temperature. After conditioning for 10 days, the resulting composite flooring was examined to assess its physical and mechanical properties, shear strength, and formaldehyde emission. Results revealed that the bioadhesive exhibited crystallinity of 23.32 percent and a melting glass transition of 115.31°C. IV-meter intrinsic viscosity tools were used to determine the product's molecular weight of 49,658. Physical–mechanical properties and shear quality of the composite flooring were similar to products that use synthetic phenolic adhesive and belong to the exterior quality type with E0 or F**** types of low formaldehyde emission.

Enhanced enzymatic transformation of 1-naphthol in the presence of catechol by peroxidase

Effect of catechol on 1-naphthol transformation by horse radish peroxidase (HRP) was examined. The impact of catechol to 1-naphthol ratio, enzyme activity, pH, and reaction time in solution were studied. The results obtained indicated that, in the presence of catechol, 1-naphthol transformation by peroxidase shows enhancement greater than that in an equivalent catechol free system. Only 27% of 1-naphthol (0.3 mM) was able to transform when catechol was absent in solution, but reached 79% in its presence (3.0 mM) in 0.1M sodium phosphate buffer (pH 7.0), and 0.3 mM H2O2 by peroxidase (0.5 unit/mL) after 3 h. The 1-naphthol transformation rate was accelerated by increase of pH or HRP concentration. High-performance liquid chromatography analysis was performed to characterize transformation products based on their relative polarities, and molecular weights of products were identified by mass spectrometry. The transformation products were found to be (hydroxy) naphthoquinones, 1-naphthol: hydroxy-naphthoquinone, and 1-naphthol oligomers (dimer, trimer, tetramer) with the molecular weights (m/z) ranging 100–600. Liquid chromatography-tandem mass spectrometry technique, to the best of our knowledge, was used for the first time to elucidate the product structure at m/z 191. The study shows that 1-naphthol is transformed rapidly by peroxidase when catechol is present, which could be useful information for improving the efficiencies of decontamination techniques.

Chemical Characterization and Antioxidant Activities of Different Sulfate Content of λ-Carrageenan Fractions from Edible Red Seaweed Chondrus ocellatus

In recent years, sulfated polysaccharides from marine algae have been demonstrated to have many activities including antioxidant activities. But whether degraded sulfated polysaccharides from Chondrus ocellatus have antioxidant activities, and what effects their sulfate content may have on those activities has not been reported. The aim of this study is to explore the antioxidant activities of λ-carrageenan fractions from edible red seaweed Chondrus ocellatus. In the present study, λ-carrageenan from Chondrus ocellatus was degraded by microwave, yielding five products of different molecular weights. Three sulfated polysaccharide fractions (CF1, CF2, and CF3) were isolated from one of the degraded λ-carrageenans (PC2) by anion-exchange column chromatography. In this study, the effects of the three polysaccharide fractions on hydroxyl radicals, superoxide radicals, organic free radical DPPH, H2O2 induced hemolysis of rat erythrocytes and lipid peroxidation in rat liver microsome were investigated. The results indicated that IR spectrum results indicated that these sulfated polysaccharide fractions had similar structures, but differed in their sulfate content. Chemical analysis indicated that CF1 had the lowest sulfate content (2.9%), while sulfate content in CF2 and CF3 was 7.8% and 37.5% respectively. CF3 had stronger scavenging activity on superoxide radical and hydroxyl radical than the other fractions (P<0.05). CF3 had the strongest scavenging activity on DPPH. the highest inhibitor of lipid peroxidation was CF3, with an IC50 of 0.087 mg/mL, and inhibitory rate reaching 90% at 1 mg/mL. All of the three fractions exhibited stronger scavenging activity at high concentration. In conclusion, sulfate group content of polysaccharides also effect on their biological activities, and which is important for antioxidant activities.

Synthesis and Characterization of Carboxyl Terminated Polydimethylsiloxanes

A series of hydrogen terminated polydimethylsiloxanes (PDMS-H) had been controlled synthesized via ring-opening polymerization. Then, methylmethacrylate (MMA) and tert-butyl methacrylate (tBMA) were grafted to PDMS-H via hydrosilylation reactions in the presence of Speier's catalyst, the hydrosilylation addition patterns of MMA and tBMA showed a strong preference toward β-1,2 addition, no α-1,2 addition product or 1,4-addition product was observed. Carboxyl terminated polydimethylsiloxanes were prepared by subsequent hydrolysis reaction in an aqueous NaOH/ethanol solution and under acid condition, respectively. Both methods could obtain carboxyl terminated polydimethylsiloxanes successfully. However, a significant decrease of the molecular weight of products was observed in the alkaline hydrolysis process, while the acid hydrolysis of tertiary butyl ester group terminated polydimethylsiloxanes could be conducted in a highly controlled manner. Besides, the synthesis of carboxyl terminated polydimethylsiloxanes via acid hydrolysis reaction can be conducted well only when the terminal group of polydimethylsiloxanes is tertiary butyl, this can be explained by the specificity of tertiary butyl.